MASAHIRO KAKO
| Division of General Education（Graduate School of Informatics and Engineering） | Professor |
| Division of General Education（School of Informatics and Engineering ） | Professor |
| Department of Engineering Science | Professor |
| Cluster III (Fundamental Science and Engineering) | Professor |
Researcher Information
Research Activity Information
Paper
- Photoreactions of Sc3N@C80 with Disilirane, Silirane, and Digermirane: A Photochemical Method to Separate Ih and D5h Isomers
M. Kako; K. Miyabe; S. Fukazawa; S. Kanzawa; M. Yasui; M. Yamada; Y. Maeda; Z. Slanina; F. Uhlík; L. Adamowicz; I. Papadopoulos; D. M. Guldi; M. Furukawa; S. Nagase; T. Akasaka
Lead, Photochem, 2, 122-137, Feb. 2022, Peer-reviwed
Scientific journal, English - Addition of S-Heterocyclic Carbenes to Fullerenes: Formation and Characterization of Dithiomethano-Bridged Derivatives
M. Kako; Y. Arikawa; S. Kanzawa; M. Yamada; Y. Maeda; M. Furukawa; T. Akasaka
Lead, Helv. Chim. Acta, 102, e1900064/1-10, Apr. 2019, Peer-reviwed
Scientific journal, English - Photoreactions of Sc3N@Ih-C80 and Lu3N@Ih-C80 with disilirane: Isolation and characterization of labile 1,2-adducts
M. Kako; F. Ozeki; S. Kanzawa; S. Fukazawa; K. Sato; M. Yamada; Y. Maeda; M. Furukawa; T. Akasaka
Lead, Heteroatom Chem., 29, e21477/1-10, Dec. 2018, Peer-reviwed
Scientific journal, English - Back Cover: Preparation, Structural Determination, and Characterization of Electronic Properties of [5,6]- and [6,6]-Carbosilylated Sc3N@I-h-C-80 (Chem. Asian J. 12/2017)
Masahiro Kako; Takeshi Sugiura; Kyosuke Miyabe; Masanori Yasui; Michio Yamada; Yutaka Maeda; Jing-Dong Guo; Shigeru Nagase; Takeshi Akasaka
Lead, CHEMISTRY-AN ASIAN JOURNAL, WILEY-V C H VERLAG GMBH, 12, 12, 1408-1408, Jun. 2017, Peer-reviwed
Scientific journal, English - Preparation, Structural Determination, and Characterization of Electronic Properties of [5,6]- and [6,6]-Carbosilylated Sc3N@I-h-C-80
Masahiro Kako; Takeshi Sugiura; Kyosuke Miyabe; Masanori Yasui; Michio Yamada; Yutaka Maeda; Jing-Dong Guo; Shigeru Nagase; Takeshi Akasaka
Lead, CHEMISTRY-AN ASIAN JOURNAL, WILEY-V C H VERLAG GMBH, 12, 12, 1391-1399, Jun. 2017, Peer-reviwed, Photochemical carbosilylation of Sc3N@I-h-C-80 with silirane 1 afforded two corresponding [5,6]-adducts, 2 and 3, and a [6,6]-adduct, 4. The structural and electronic properties of these products were characterized by means of spectroscopic, electrochemical, and theoretical methods. The structure of 2 was disclosed by means of single-crystal X-ray crystallographic analysis. Thermal isomerization of 3 to 2 was observed, whereas that of 2 to 3 proceeded less efficiently at 100 degrees C. Upon heating under the same conditions, adduct 4 underwent facile decomposition to afford Sc3N@I-h-C-80, or isomerized into small amounts of 2 and 3. The relative stabilities of 2, 3, and 4 were rationalized through the results of theoretical calculations. In contrast, adducts 2, 3, and 4 were stable under the photolytic conditions employed for carbosilylation. The photochemical functionalization of Sc3N@I-h-C-80 represents a convenient synthetic method to obtain thermally labile fullerene-based products.
Scientific journal, English - Photoreactions of Endohedral Metallofullerene with Siliranes: Electronic Properties of Carbosilylated Lu3N@I-h-C-80
Masahiro Kako; Kazuya Minami; Taiki Kuroiwa; Shinpei Fukazawa; Yuki Arikawa; Michio Yamada; Yutaka Maeda; Qiao-Zhi Li; Shigeru Nagase; Takeshi Akasaka
Lead, MOLECULES, MDPI AG, 22, 5, 850-859, May 2017, Peer-reviwed, Photochemical carbosilylation of Lu3N@I-h-C-80 was performed using siliranes (silacyclopropanes) to afford the corresponding [5,6]- and [6,6]-adducts. Electrochemical studies indicated that the redox potentials of the carbosilylated derivatives were shifted cathodically in comparison with those of the [5,6]-pyrrolidino adducts. The electronic effect of the silirane addends on Lu3N@I-h-C-80 was verified on the basis of density functional theory calculations.
Scientific journal, English - Photochemical addition of silirane to endohedral metallofullerene: Electronic properties of carbosilylated Sc3N@l(h)-C80
Masahiro Kako; Takeshi Sugiura; Takeshi Akasaka
Lead, PHOSPHORUS SULFUR AND SILICON AND THE RELATED ELEMENTS, TAYLOR & FRANCIS LTD, 191, 2, 201-206, Feb. 2016, Peer-reviwed, The photochemical reaction of Sc3N@I-h-C-80 with silirane 1 produced the corresponding carbosilylated derivatives. The electrochemical studies of [5,6]-adducts indicate that carbosilylation is an effective method for tuning moderately the electronic characteristics of Sc3N@I-h-C-80. Density functional theory calculations were also conducted to offer a theoretical basis for the electronic properties of carbosilylated derivatives.
Scientific journal, English - Preparation, Structural Determination, and Characterization of Electronic Properties of Bis-Silylated and Bis-Germylated Lu3 N@Ih -C80.
Kako M; Miyabe K; Sato K; Suzuki M; Mizorogi N; Wang WW; Yamada M; Maeda Y; Olmstead MM; Balch AL; Nagase S; Akasaka T
Lead, Chemistry (Weinheim an der Bergstrasse, Germany), 21, 46, 16289, Nov. 2015, Peer-reviwed - Preparation, Structural Determination, and Characterization of Electronic Properties of Bis-silylated and Bis-germylated Lu3N@I-h-C-80
Masahiro Kako; Kyosuke Miyabe; Kumiko Sato; Mitsuaki Suzuki; Naomi Mizorogi; Wei-Wei Wang; Michio Yamada; Yutaka Maeda; Marilyn M. Olmstead; Alan L. Balch; Shigeru Nagase; Takeshi Akasaka
Lead, CHEMISTRY-A EUROPEAN JOURNAL, WILEY-V C H VERLAG GMBH, 21, 46, 16411-16420, Nov. 2015, Peer-reviwed, Bis-silylated and bis-germylated derivatives of Lu3N@I-h-C-80 (3, 4, 5) were successfully synthesized by the photochemical addition of disiliranes 1a, 1b or digermirane 2, and fully characterized by spectroscopic, electrochemical, and theoretical studies. Interestingly, digermirane 2 reacts more efficiently than disiliranes 1a and 1b because of its good electron-donor properties and lower steric hindrance around the GeGe bond. The 1,4-adduct structures of 3, 4, 5 were unequivocally established by single-crystal X-ray crystallographic analyses. The electrochemical and theoretical studies reveal that the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the 1,4-adducts are remarkably smaller than those of Lu3N@I-h-C-80, because the electron-donating groups effectively raise the HOMO levels. It is also observed that germyl groups are slightly more electron-donating than the silyl groups on the basis of the redox properties and the HOMO-LUMO energies of 4 and 5. Bis-silylation and bis-germylation are effective and versatile methods for tuning the electronic characteristics of endohedral metallofullerenes.
Scientific journal, English - Thermal Reactions of Fullerenes with Cyclic Organosilicon and Organogermanium Compounds: Silylation and Germylation of C-60 and C-70
Masahiro Kako; Daiki Inaba; Kazuya Minami; Ryosuke Iida; Tsukasa Nakahodo; Takeshi Akasaka
Lead, HETEROATOM CHEMISTRY, WILEY-BLACKWELL, 25, 6, 584-591, Nov. 2014, Peer-reviwed, Thermal reactions of empty fullerenes with disilirane (1) and digermirane (2) afforded the corresponding bis-silylated and bis-germylated derivatives. When a bicyclic fused silirane (3a) was heated in the presence of C-70, two silylene adducts were obtained through thermal extrusion of silylenes. These results provide a complementary method to the photochemical addition of reactive silicon and germanium compounds, which have been long employed for derivatization of fullerenes. Electrochemical analyses revealed the redox properties of the silylated and germylated C-70, indicating the electronic perturbation caused by silyl and germyl groups introduced on the fullerene cages. Theoretical calculations were also conducted for understanding of the electronic property of the fullerene derivatives. C (C) 2014 Wiley Periodicals, Inc.
Scientific journal, English - Thermal Reactions of C60 with Siliranes: Carbosilylation and Silylene Addition of Fullerenes
Masahiro Kako; Ryosuke Iida; Yutaka Maeda; Michio Yamada; Tadashi Hasegawa
Lead, FULLERENES NANOTUBES AND CARBON NANOSTRUCTURES, TAYLOR & FRANCIS INC, 22, 1-3, 155-165, Jan. 2014, Peer-reviwed, Thermal reactions of C-60 with siliranes (1a, b) afforded carbosilylated C-60 derivatives. When a bicyclic fused silirane (1c) was employed instead of 1a and 1b, a silylene adduct and its hydrolyzed compound were obtained through thermal extrusion of silylenes from 1c. These products were determined to be 1,2-adducts at 6,6-junctions of C-60 by MS, UV, and NMR analyses. These results provide a complementary method to the photochemical addition of reactive silicon compounds, which have been long employed for silylation of C-60. Electrochemical analyses revealed the redox properties of the silylated products, indicating the perturbation caused by silyl groups introduced on the C-60 cage. Theoretical calculations were also conducted for understanding of the electronic property of the silylated product.
Scientific journal, English - Bis-Silylation of Lu3N@I-h-C-80: Considerable Variation in the Electronic Structures
Kumiko Sato; Masahiro Kako; Naomi Mizorogi; Takahiro Tsuchiya; Takeshi Akasaka; Shigeru Nagase
ORGANIC LETTERS, AMER CHEMICAL SOC, 14, 23, 5908-5911, Dec. 2012, Peer-reviwed, Photochemical reactions of Lu3N@I-h-C-80 with disiliranes 1 and 2 produce several isomeric adducts. Spectroscopic analyses characterize the most stable isomers as 1,4(AA) adducts, which consist of paired twist conformers at rt. The electrochemical and theoretical studies reveal that the HOMO-LUMO energy gaps of the 1,4(AA) adducts are smaller than that of Lu3N@I-h-C-80 because the electron-donating groups effectively raise the HOMO levels.
Scientific journal, English - Analysis of Functionalization Degree of Single-Walled Carbon Nanotubes Having Various Substituents
Yutaka Maeda; Kazuma Saito; Norihisa Akamatsu; Yuriko Chiba; Seina Ohno; Yumi Okui; Michio Yamada; Tadashi Hasegawa; Masahiro Kako; Takeshi Akasaka
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 134, 43, 18101-18108, Oct. 2012, Peer-reviwed, Introducing substituents onto SWNT sidewalls increases their solubility and tunes their properties. Controlling the degree of functionalization is important because the addition of numerous functional groups on the sidewall degrades their intrinsic useful electronic properties. We examined the synthesis and characterization of sidewall-functionalized SWNTs in this study. The functionalized SWNTs (R-1-SWNTs-R-2) were prepared in a one-pot reaction of SWNTs with alkyllithium ((RLi)-R-1) followed by alkyl bromide ((RBr)-R-2). The functionalized SWNTs were characterized by the absorption and Raman spectroscopy and thermogravimetric analysis. Not only the total number of functional groups introduced on the SWNT sidewall (formula mass: R-1 = R-2) but also the ratio of R-2 to R-1 in the fimctionalized SWNTs (formula mass: R-1 not equal R-2) having two different substituents were clarified using the relation between results of Raman spectroscopy and thermogravimetric analysis. Results show that the degree of functionalization of R-2 to R-1 in R-1-SWNTs-R-2 can be well controlled by the bulkiness of the alkyl groups of (RLi)-R-1 and (RBr)-R-2. Moreover, substituent effects of reductive alkylation and reductive silylation of SWNTs via Birch reduction were investigated.
Scientific journal, English - Synthesis of Silylene-Bridged Endohedral Metallofullerene Lu3N@Ih-C80
Kumiko Sato; Masahiro Kako; Mitsuaki Suzuki; Naomi Mizorogi; Takahiro Tsuchiya; Marilyn M. Olmstead,Alan L. Balch; Takeshi Akasaka; Shigeru Nagase
Journal of the American Chemical Society, 134, 38, 16033-16039, 18 Sep. 2012, Peer-reviwed
Scientific journal, English - Synthesis of Silylene-Bridged Endohedral Metallofullerene Lu3N@I-h-C-80
Kumiko Sato; Masahiro Kako; Mitsuaki Suzuki; Naomi Mizorogi; Takahiro Tsuchiya; Marilyn M. Olmstead; Alan L. Balch; Takeshi Akasaka; Shigeru Nagase
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 134, 38, 16033-16039, Sep. 2012, Peer-reviwed, Functionalization of endohedral metallofullerenes has been shown to differ depending on photochemical or thermal pathways. We report that Lu3N@I-h-C-80 reacts with thermally generated bis(2,6-diethylphenyl)silylene with high selectivity and forms monosilylated derivative 1b. Unexpectedly, 1b undergoes photochemical conversion to afford isomer 1a under ambient light. These adducts were characterized using NMR, visible-near-IR spectroscopy, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Single-crystal X-ray structure determination of 1a reveals a rare example of an open 1,2-adduct at the [5,6]-ring junction of the I-h-C-80 cage. The electrochemical study reveals that the redox potentials of 1a and 1b are shifted cathodically compared to those of pristine Lu3N@I-h-C-80 and that monosilylation is effective to fine-tune the electronic properties of endohedral metallofullerenes as well as empty fullerenes. Density functional theory calculations were also performed, which provide a theoretical basis for the structures and the behavior of the encapsulated Lu3N cluster.
Scientific journal, English - Thermal Carbosilylation of Endohedral Dimetallofullerene La-2@I-h-C-80 with Silirane
Michio Yamada; Mari Minowa; Satoru Sato; Masahiro Kako; Zdenek Slanina; Naomi Mizorogi; Takahiro Tsuchiya; Yutaka Maeda; Shigeru Nagase; Takeshi Akasaka
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 132, 50, 17953-17960, Dec. 2010, Peer-reviwed, Thermal carbosilylation of endohedral dimetallofullerene La-2@I-h-C-80 with silirane (silacyclopropane) is reported herein for the first time. Two diastereomers of the carbosilylated La-2@I-h-C-80 have been isolated and characterized. The fascinating molecular structure of one diastereomer of the carbosilylated derivatives has been determined unambiguously using X-ray crystallographic analysis. Detailed characteristics of the molecular structures including their metal atom movements have also been revealed using NMR spectroscopic studies and computational calculations. Results revealed that two La atoms move dynamically inside the carbon sphere. Furthermore, electrochemical study has demonstrated that carbosilylation is effective to fine-tune the La-2@I-h-C-80 electronic properties.
Scientific journal, English - Photochemical Addition of C-60 with Siliranes: Synthesis and Characterization of Carbosilylated and Hydrosilylated C-60 Derivatives
Junko Nagatsuka; Sachie Sugitani; Masahiro Kako; Tsukasa Nakahodo; Naomi Mizorogi; Midori O. Ishitsuka; Yutaka Maeda; Takahiro Tsuchiya; Takeshi Akasaka; Xingfa Gao; Shigeru Nagase
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 132, 34, 12106-12120, Sep. 2010, Peer-reviwed, Photochemical reactions of C-60 with siliranes (1a-d) afford adducts of four types (2a-5b) as carbosilylated and hydrosilylated C-60 derivatives. Characterization of these adducts was conducted using MS, UV, NMR spectroscopy, and single-crystal X-ray analyses. In particular, the first example of the crystal structure of a closed 1,2-adduct at the 5,6-ring junction of the C-60 cage is provided by single-crystal X-ray analysis of 3b. Electrochemical analyses also revealed unique redox properties of the products 2b-5b, which depend on the regiochemistry of the functionality, in addition to the substituents on the C-60 cage. Theoretical calculations offer bases for the experimentally observed redox properties and relative stabilities of the silylated products.
Scientific journal, English - Two-Step Alkylation of Single-Walled Carbon Nanotubes: Substituent Effect on Sidewall Functionalization
Yutaka Maeda; Takaaki Kato; Tadashi Hasegawa; Masahiro Kako; Takeshi Akasaka; Jing Lu; Shigeru Nagase
ORGANIC LETTERS, AMER CHEMICAL SOC, 12, 5, 996-999, Mar. 2010, Peer-reviwed, A two-step alkylation of single-walled carbon nanotubes was investigated. The functionalized SWNTs were characterized with vis-NIR and Raman spectrometers, scanning electron microscope, and thermogravimetric analysis. This one-pot alkylation of SWNTs with alkyllithium followed by alkyl halide is useful for the sidewall functionalization of SWNTs. This reaction shows significant substituent effects on the degree of functionalization of SWNTs. The degree of functionalization on SWNTs sidewall upon SWNTs may influence their characteristic properties on SWNTs sidewall by the substituent effects.
Scientific journal, English - A new method for separating the D-3 and C-2v isomers of C-78
Ai Hong Han; Takatsugu Wakahara; Yutaka Maeda; Takeshi Akasaka; Mamoru Fujitska; Osamu Ito; Kazunori Yamamoto; Masahiro Kako; Kaoru Kobayashi; Shigeru Nagase
NEW JOURNAL OF CHEMISTRY, ROYAL SOC CHEMISTRY, 33, 3, 497-500, 2009, Peer-reviwed, A new chemical method has been applied to isolate isomers of C-78. The photochemical cycloaddition of a mixture of C-78(D-3) and C-78(C-2v) with a disilirane affords only the mono-adduct of the C-2v isomer of C-78. Its counterpart does not give the mono-adduct with a disilirane. The D-3 isomer itself and the adduct of the C-2v isomer of C-78 with a disilirane are easily separated by a HPLC procedure. A facile oxidative desilylation of the adduct takes place, resulting in the formation of pristine C-78(C-2v). In this context, the separation and isolation of the two isomers of C-78 were successfully accomplished by using a silylation-oxidative desilylation process.
Scientific journal, English - Two-dimensional hopping motion of encapsulated La atoms in silylated La-2@C-80
Wakahara Takatsugu; Yamada Michio; Takahashi Satomi; Nakahodo Tsukasa; Tsuchiya Takahiro; Maeda Yutaka; Akasaka Takeshi; Kako Masahiro; Yoza Kenji; Horn Ernst; Mizorogi Naomi; Nagase Shigeru
Chemical Communications, 26, 2680-2682, 2007, Peer-reviwed - Characterization of the bis-silylated endofullerene Sc3N@C 80
T. Wakahara; Y. Iiduka; O. Ikenaga; T. Nakahodo; A. Sakuraba; T. Tsuchiya; Y. Maeda; M. Kako; T. Akasaka; K. Yoza; E. Horn; N. Mizorogi; S. Nagase
Journal of the American Chemical Society, AMER CHEMICAL SOC, 128, 30, 9919-9925, 2006, Peer-reviwed, The photochemical reaction of Sc3N@C-80 with 1,1,2,2-tetramesityl-1,2-disilirane affords the adduct as a bis-silylated product. The adduct was characterized by NMR spectroscopy and single-crystal X-ray structure analysis. The dynamic behavior of the disilirane moiety and the encapsulated Sc3N cluster were also investigated. The unique redox property of the adduct is reported by means of CV and DPV. Experimental results were confirmed by density functional calculations.
Scientific journal, English - Preparation of Single-Walled Carbon Nanotubes-Organosilicon Hybrids and Their Enhanced Field Emission Properties
Yutaka Maeda; Yoshinori Sato; Masahiro Kako; Takatsugu Wakahara; Takeshi Akasaka; Jing Lu; Shigeru Nagase; Yumiko Kobori; Tadashi Hasegawa; Kenichi Motomiya; Kazuyuki Tohji; Atsuo Kasuya; Dan Wang; Dapeng Yu; Zhengxiang Gao; Rushan Han; Hengqiang Ye
Chemistry of Materials, 18, 18, 4205-4208, Jan. 2006, Peer-reviwed
Scientific journal, English - Synthesis and characterization of exohedrally silylated M@C-82 (M = Y and La)
M Yamada; L Feng; T Wakahara; T Tsuchiya; Y Maeda; YF Lian; M Kako; T Akasaka; T Kato; K Kobayashi; S Nagase
JOURNAL OF PHYSICAL CHEMISTRY B, AMER CHEMICAL SOC, 109, 13, 6049-6051, Apr. 2005, Peer-reviwed, The silylation of endohedral mono-metallofullerenes (Y@C-82 and La@C-82) and isolation of the corresponding adducts by HPLC separation have been accomplished. The redox properties of the silylated mono-metallofullerene were first clarified by CV and DPV measurements, indicating that the bis-silylated mono-metallofullerenes have lower oxidation and higher reduction potentials than the parent mono-metallofullerenes. These results reveal that bis-silylation is very effective for producing the electronegatively mono-metallofullerene derivatives as well as empty fullerenes.
Scientific journal, English - Chemical reactivities of the cation and anion of M@C-82 (M = Y, La, and Ce)
Y Maeda; J Miyashita; T Hasegawa; T Wakahara; T Tsuchiya; L Feng; YF Lian; T Akasaka; K Kobayashi; S Nagase; M Kako; K Yamamoto; KM Kadish
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 127, 7, 2143-2146, Feb. 2005, Peer-reviwed, The chemical reduction and oxidation of M @ C-82 (M = Y, La, and Ce) afford the corresponding anion and cation, respectively, which show unique and interesting chemical reactivities. It is found that the successful reversible gain or loss of electrons by ionization is useful for controlling the stability and reactivity of M @ C-82 toward both nucleophiles and electrophiles.
Scientific journal, English - Chemical reactivity of Sc3N@C80 and La 2@C80
Y. Iiduka; O. Ikenaga; A. Sakuraba; T. Wakahara; T. Tsuchiya; Y. Maeda; T. Nakahodo; T. Akasaka; M. Kako; N. Mizorogi; S. Nagase
Journal of the American Chemical Society, 127, 28, 9956-9957, 2005, Peer-reviwed
English - Positional control of encapsulated atoms inside a fullerene cage by exohedral addition
Yamada M; Nakahodo T; Wakahara T; Tsuchiya T; Maeda Y; Akasaka T; Kako M; Yoza K; Horn E; Mizorogi N; Kobayashi K; Nagase S
Journal of the American Chemical Society, 127, 42, 14570-14571, 2005, Peer-reviwed - Characterization of Ce@C-82 and its anion
T Wakahara; J Kobayashi; M Yamada; Y Maeda; T Tsuchiya; M Okamura; T Akasaka; M Waelchli; K Kobayashi; S Nagase; T Kato; M Kako; K Yamamoto; KM Kadish
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 126, 15, 4883-4887, Apr. 2004, Peer-reviwed, Ce@C-82 is isolated by high-performance liquid chromatography (HPLC) and the cage symmetry is determined as C-2v by measuring the C-13 NMR spectra of its anion. The C-13 NMR peaks of [Ce@C-82](-) show temperature-dependent shifts ascribed to the f electron remaining on the Ce atom. Both Ce@C82 and [Ce@C-82](-) are silent in electron spin resonance spectroscopy (ESR) because of the highly anisotropic g matrix as well as of the fast relaxation process originating from the orbital angular momentum of the f electron. This is the complementary relationship to the observation of the paramagnetic shift in 13 C NMR. [Ce@C-82](-) has lower stability in air than [La@C-82](-).
Scientific journal, English - Characterization of Ce@C-82 and its anion
Wakahara, T; Kobayashi, J; Yamada, M; Maeda, Y; Tsuchiya, T; Okamura, M; Akasaka, T; Waelchli, M; Kobayashi, K; Nagase, S; Kato, T; Kako, M; Yamamoto, K; Kadish, KM
Journal of the American Chemical Society, 126, 15, 2004, Peer-reviwed
Scientific journal, English - Silylation of fullerenes with active species in photolysis of polysilane
T Wakahara; Y Maeda; M Kako; T Akasaka; K Kobayashi; S Nagase
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 685, 1-2, 177-188, Nov. 2003, Peer-reviwed, Organosilicon compounds represent a unique feature of materials such as disilane and polysilane. Meanwhile, since the isolation of C-60 and C-70 in preparatively useful quantities, much attention has been devoted to chemical functionalization of these new allotropic forms of carbon, which continuously yields fascinating results. It can be expected that a combination of organosilicon compounds and fullerene forms a new class of organic compounds and at the same time opens a new field in material science. In this context, we have carried out the reaction of fullerenes with active species generated in photolysis of disilane and polysilane, by which we can obtain an attractive material and also clarify the chemical and electronic properties of fullerenes. We here summarize the recent advances in the chemistry of mono- and bis-silylation of fullerenes with silylene and silyl radical to afford the corresponding new fullerene-based organosilicon materials. (C) 2003 Elsevier Science B.V. All rights reserved.
Scientific journal, English - Synthesis and characterization of tetrakis-silylated C-60 isomers
Y Maeda; GMA Rahman; T Wakahara; M Kako; M Okamura; S Sato; T Akasaka; K Kobayashi; S Nagase
JOURNAL OF ORGANIC CHEMISTRY, AMER CHEMICAL SOC, 68, 17, 6791-6794, Aug. 2003, Peer-reviwed, A photochemical reaction Of C-60 with disilane in a 2:3 ratio affords the isomer mixture of the tetrakis-adduct of C-60((BuPh2Si)-Bu-t)(4) as the major product. The use of a three-stage HPLC separation system isolated three of their isomers. Their structural assignments were based on FAB mass, UV-vis, NMR, and cyclic voltammetry (CV) measurements. The CV analysis showed that the terakis-adduct has lower oxidation and higher reduction potentials than the bisadduct C-60((BuPh2Si)-Bu-t)(2) and the parent C-60.
Scientific journal, English - Synthesis and characterization of cyclic silicon compounds of fullerenes
T Wakahara; M Kako; Y Maeda; T Akasaka; K Kobayashi; S Nagase
CURRENT ORGANIC CHEMISTRY, BENTHAM SCIENCE PUBL LTD, 7, 10, 927-943, Jul. 2003, Peer-reviwed, Organosilicon compounds are perhaps the most important inter-element compounds, as exemplified by disilanes and polysilanes. Similarly, ever since fullerene C-60 became available in preparatively useful quantities, this new allotropic form of carbon has attracted much attention, particularly its chemical functionalization. The present review describes how these two disparate classes of compound can be induced to react together and combine to form novel derivatives endowed with unusual properties. In particular, we describe how silylenes derived from various disilane derivatives under thermal and photochemical conditions can react with fullerenes and endohedral metallofullerenes. Mono- bis- and even multi-silylation of the fullerene framework takes place leading to a new class of fullerene-based organic compounds which at the same time opens a promising new field in materials science.
Scientific journal, English - One Step Synthesis of Highly-Pure Soluble Single-Walled Carbon Nanotubes
Yutaka Maeda; Yongfu Lian; Takatsugu Wakahara; Masahiro Kako; Takeshi Akasaka; Nami Choi; Hiroshi Tokumoto; Said Kazaoui; Nobutsugu Minami
ITE Letters on Batteries, New Technologies & Medicine, 4, 6, 798-801, 2003 - Redox Properties of Carbosilylated and Hydrosilylated Fullerene Derivatives
T. Wakahara; G. M. A. Rahman; Y. Maeda; M. Kako; S. Sato; M. Okamura; T. Akasaka; K. Kobayashi; S. Nagase
ITE Lett., 4, C24-C30, 2003, Peer-reviwed
Scientific journal, English - Photochemical Bissilylation of C70 with Disilane
G. M. A. Rahman; Y. Maeda; T. Wakahara; M. Kako; S. Sato; M. Okamura; T. Akasaka; K. Kobayashi; S. Nagase
ITE Lett., 4, C17-C23, 2003, Peer-reviwed
Scientific journal, English - A comparison of the photochemical reactivity of N@C-60 and C-60: photolysis with disilirane
T Wakahara; Y Matsunaga; A Katayama; Y Maeda; M Kako; T Akasaka; M Okamura; T Kato; YK Choe; K Kobayashi; S Nagase; HJ Huang; M Atae
CHEMICAL COMMUNICATIONS, ROYAL SOC CHEMISTRY, 23, 2940-2941, 2003, Peer-reviwed, N@C-60 has a lower photochemical reactivity toward disilirane than C-60, although N@C-60 does not differ from C-60 in its thermal reactivity; theoretical calculations reveal that N@C-60 and C-60 have the same orbital levels and that N@C-3(60)* has a shorter lifetime than C-3(60)*.
Scientific journal, English - Ionization and structural determination of the major isomer of Pr Γ82
T. Wakahara; S. Okubo; M. Kondo; Y. Maeda; T. Akasaka; M. Waelchli; M. Kako; K. Kobayashi; S. Nagase; T. Kato; K. Yamamoto; X. Gao; E. Van Caemelbecke; K.M. Kadish
Chemical Physics Letters, 360, 3-4, 235-239, 10 Jul. 2002, Peer-reviwed
English - Endohedral fullerene ions: Synthesis, structure and reaction
T Wakahara; Y Maeda; S Ohkubo; J Kobayashi; M Kondo; T Akasaka; K Kobayashi; S Nagase; T Kato; M Kako; K Yamamoto; KM Kadish
STRUCTURAL AND ELECTRONIC PROPERTIES OF MOLECULAR NANOSTRUCTURES, AMER INST PHYSICS, 633, 43-46, 2002, Peer-reviwed, Endohedralmetallofullerene ions Of M@C-82 (M=Ce, Pr) were synthesized by electrochemical methods. The structures of these M@C-82 were determined by 13C NMR measurements of their anions. Reactions of these M@C-82 ions are also reported.
International conference proceedings, English - Silylation of higher fullerenes
T. Wakahara; A. Han; Y. Niino; Y. Maeda; T. Akasaka; T. Suzuki; K. Yamamoto; M. Kako; Y. Nakadaira; K. Kobayashi; S. Nagase
Journal of Materials Chemistry, 12, 7, 2061-2064, 2002, Peer-reviwed
English - Novel photocycloaddition of aromatic ketones to cyclic oligosilanes
M Kako; M Gu; Y Takenaka; K Takagi; K Kondo; Y Nakadaira; M Wakasa; H Hayashi
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 12, 1220-1221, Dec. 2001, Peer-reviwed, Photolysis of aromatic ketones (2,2,2-trifluoroacetophenone, acetophenone, and benzophenone) in the presence of cyclic oligosilanes afforded two types of cycloadducts depending on the nature of the ketone employed. The quenching of the excited triplet state of benzophenone by oligosilanes was investigated by laser flash photolysis.
Scientific journal, English - Silylene-transfer reactions of cyclic organosilanes induced by phenanthraquinone triplet
M Kako; M Ninomiya; M Gu; Y Nakadaira; M Wakasa; H Hayashi; T Akasaka; T Wakahara
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 636, 1-2, 63-68, Nov. 2001, Peer-reviwed, On irradiation cyclic organosilanes 1a-b, 7 and 8 react with phenanthraquinone (PQ) to afford corresponding dioxasilolenes 2a-b as sitylene-transfer products. The quenching experiment by anthracene reveals that PQ should act as triplet ((3)PQ*) to undergo radical displacement at the silicon atom of 1a-b. In polar solvents, electron-transfer from 1a-b to (3)PQ* would generate PQ radical anion and the coupling of the radical ion pair formed would cause the Si-Si bond cleavage followed by intramolecular O-Si bond formation to give silylene transfer product 2a-b. Since the photolysis of PQ with 1a-b in the presence of CCl4 gives dichlorooligosilanes, intermediacy of oligosilanyl radicals is highly probable. The quenching rate constant k(q) of (3)PQ* by cyclic organosilane lb has been determined by laser flash photolysis. In a mixed solvent of CH3CN and CH2Cl2, (3)PQ* is readily quenched by the addition of 1b with the formation of PQ radical anion. On the other hand, since PQ radical anion has not been observed on the laser photolysis, the quenching of (3)PQ* with lb in benzene should be less efficient. (C) 2001 Elsevier Science B.V. All rights reserved.
Scientific journal, English - Photochemical cycloaddition of C-78 with disilirane
AH Han; T Wakahara; Y Maeda; Y Niino; T Akasaka; K Yamamoto; M Kako; Y Nakadaira; K Kobayashi; S Nagase
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 10, 974-975, Oct. 2001, Peer-reviwed, The photochemical cycloaddition of C-78(C-2v+D-3) with disilirane 1 only gave the adducts of C-78(C-2v). The D-3 isomer of C-78 did give no adduct with 1. The two mono-adducts were firstly isolated by a multi-stage HPLC, and characterized on the basis of the spectroscopic data. The electrochemical properties were also investigated by means of differential pulse voltammetry.
Scientific journal, English - Structural determination of the La@C-82 isomer
T Akasaka; T Wakahara; S Nagase; K Kobayashi; M Waelchli; K Yamamoto; M Kondo; S Shirakura; Y Maeda; T Kato; M Kako; Y Nakadaira; Gao, X; E Van Caemelbecke; KM Kadish
JOURNAL OF PHYSICAL CHEMISTRY B, AMER CHEMICAL SOC, 105, 15, 2971-2974, Apr. 2001, Peer-reviwed, stable diamagnetic monoanion of the La@C-82 isomer was electrochemically prepared and isolated in order to disclose its cage symmetry. By measuring the C-13 NMR spectrum of the anion, it was determined for the first time that the isomer has C-s symmetry, as was also confirmed by density functional calculations.
Scientific journal, English - Photoinduced electron-transfer reactions between C-60 and cyclic disiliranes (c-R2Si-X-SiR2; X = SiR2, CH2, O, NPh, S)
Y Sasaki; M Fujitsuka; O Ito; Y Maeda; T Wakahara; T Akasaka; K Kobayashi; S Nagase; M Kako; Y Nakadaira
HETEROCYCLES, PERGAMON-ELSEVIER SCIENCE LTD, 54, 2, 777-+, Feb. 2001, Peer-reviwed, Photoinduced electron-transfer reactions between various cyclic disiliranes (c-R2Si-X-SiR2; X = SiR2,CH2, O, NPh, and S) and photo-excited C-60 in polar PhCN solvent have been investigated by 532 nm laser photolysis with the observation of the transient absorption bands in the near-IR region. The transient absorption band of the anion radical of C-60 (C-60(.-)) appeared at 1070 nm, accompanying the decay of the excited triplet state of C-60 (C-3(60)*), showing that electron transfer takes place from c-R2Si-X-SiR2 to C-3(60)*. The rates and quantum yields for electron transfer via C-3(60)* were compared with changing X. The final products in PhCN were identified as mono-adducts and bis-adducts of R2Si-X-SiR2 with PhCN, but not with C-60.
Scientific journal, English - Chemistry of endohedral metallofullerene ions
T Akasaka; T Wakahara; S Nagase; K Kobayashi; M Waelchli; K Yamamoto; M Kondo; S Shirakura; Y Maeda; T Kato; M Kako; Y Nakadaira; Gao, X; E Van Caemelbecke; KA Kadish
NANONETWORK MATERIALS: FULLERENES, NANOTUBES AND RELATED SYSTEMS, AMER INST PHYSICS, 590, 465-468, 2001, Peer-reviwed, The anion of La@C-82 was electrochemically prepared and isolated. Anionic La@C-82(-) is very stable in water, even after exposure to air at room temperature. The high stability of La@C-82(-) is essentially due to its closed-shell electronic structure. As evidenced by the ESR analysis, La@C-82(-) is diamagnetic. These experimental findings are confirmed by density functional calculations. The cage structure of La@C-82 was determined for the first time and shown to have C-2V symmetry based on the C-13 NMR measurements of the compound in its anionic form.
International conference proceedings, English - Chemistry of endohedral metallofullerene ions: Structural determination of the La@C-82 isomer
T Akasaka; T Wakahara; M Kondo; S Shirakura; Y Maeda; S Nagase; K Kobayashi; M Waelchli; K Yamamoto; T Kato; M Kako; Y Nakadaira; Gao, X; E Van Caemelbecke; KM Kadish
FULLERENES FOR THE NEW MILLENNIUM, ELECTROCHEMICAL SOCIETY INC, 2000, 11, 323-331, 2001, Peer-reviwed
International conference proceedings, English - Photo-induced electron-transfer reactions of cyclic organosilanes and related compounds
M Kako; Y Nakadaira
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, CHEMICAL SOC JAPAN, 73, 11, 2403-2422, Nov. 2000, Peer-reviwed, Under photo-induced ET conditions in the presence of CCl4 and BF4-, a Si-Si sigma -bond readily undergoes chlorinative and fluorinative cleavage, and gives the corresponding chloro- and fluoro-silanes in good yields. In contrast co-photolysis of an aromatic nitrile with a disilane and a tetraalkyl group 14 metal effects selective silylation and alkylation of the nucleus at the position where spin density is high on its radical anion. Chlorination with CCl4 and the intra-molecular trap with the hydroxy group have clarified the radical cationic nature of the intermediate in the photo-induced electron transfer reactions of organooligosilanes. On the other hand, on photo-induced electron transfer, 7-silabicyclo[2.2.1]heptadiene derivatives undergo skeletal rearrangement to give 2-silabicyclo[3.2.0]heptadiene and 1-silabicyclo[2.2.1]heptadiene derivatives which are also the products from the direct photolysis. 7,8-Disilabicyclo[2.2.2]octadiene derivatives afford 1,2-dimethoxydisilane and 1,2-difluorodisilane, respectively on photo-induced electron transfer in the presence of methanol and BF4-. 1, 2-Disilacyclohexadiene derivatives undergo ring contraction to give the corresponding silacyclopentadienes under photoinduced electron transfer conditions. Structural and electronic characteristics of the radical cation derived from these cyclic unsaturated organosilanes by MO calculations have been discussed.
Scientific journal, English - C-60-sensitized bis-silylation of nitrile and carbonyl compounds with disilirane
Y Maeda; R Sato; T Wakahara; M Okamura; T Akasaka; M Fujitsuka; O Ito; K Kobayashi; S Nagase; M Kako; Y Nakadaira; E Horn
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 611, 1-2, 414-419, Oct. 2000, Peer-reviwed, The photochemical reaction of disilirane with unsaturated compounds such as nitrile, ketone and aldehyde in the presence of C-60 with a halogen lamp (cutoff <400 nm) affords the corresponding adducts of disilirane and unsaturated compounds as bis-silylated products. The experimental results by using laser hash photolysis technique confirm the formation of the adducts via a photoinduced electron transfer process between 1 and 3C(60)*. I, this bis-silylation reaction, C-60 serves as a sensitizer. (C) 2000 Elsevier Science S.A. All rights reserved.
Scientific journal, English - Photochemical bis-silylation of C-60: synthesis of a novel C-60 main chain polysilane
T Wakahara; T Kondo; M Okamura; T Akasaka; Y Hamada; T Suzuki; M Kako; Y Nakadaira
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 611, 1-2, 78-84, Oct. 2000, Peer-reviwed, The photoreaction of polysilanes and cyclic oligosilanes with C-60 has been investigated. Photoirradiation of a solution of C-60 and polysilanes in benzene in a degassed quartz tube at 20 degrees C with a low-pressure mercury-are lamp has afforded the C-60-polysilane adduct in moderate yield, in which C-60 is incorporated into the polysilane chain. A unique electronic property of the C-60 main chain polysilane has also been elucidated. (C) 2000 Elsevier Science S.A. All rights reserved.
Scientific journal, English - A 3,4-benzo-1,2-germacyclobut-3-ene and related compounds. Palladium-catalyzed sigma-metathesis, dehydrogenative coupling and hydrogermylation of the Ge-Ge sigma-bond
H Komoriya; M Kako; Y Nakadaira; K Mochida
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 611, 1-2, 420-432, Oct. 2000, Peer-reviwed, In the presence of catalytic amounts of Pd(PPh3)(4), 3,4-benzo-1,1,2,2-tetraethyl-1,2-germacyclobut-3-ene (1) readily undergoes the reversible sigma-bond metathesis to give a dimer, 1,2,5,6-dibenzo-3,4,7,8-tetragermacycloocta-1,5-diene (6) below 100 degrees C. However, at 160 degrees C in toluene containing catalytic amounts of Pd(PPh3)(4), both 1 and 6 afford an unsymmetrical dimer, 1,2,4,5-dibenzo-3,6,7,8-tetragermacycloocta-1,4-diene (8) with two isomeric products. In the presence of Pd(PPh3)(4), 1,2-bis(diethylgermyl)benzene (18) undergoes dehydrocouling to give 1, which is smoothly converted to 6 under these conditions. The metal-metal sigma-bonds of 1 and its silicon analogue are highly susceptible to hydrogermylation but not to hydrosilylation in the presence of Pd(PPh3)(4). (C) 2000 Elsevier Science S.A. All rights reserved.
Scientific journal, English - La@C-82 anion. An unusually stable metallofullerene
T Akasaka; T Wakahara; S Nagase; K Kobayashi; M Waelchli; K Yamamoto; M Kondo; S Shirakura; S Okubo; Y Maeda; T Kato; M Kako; Y Nakadaira; R Nagahata; Gao, X; E Van Caemelbecke; KM Kadish
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 122, 38, 9316-9317, Sep. 2000, Peer-reviwed
Scientific journal, English - A first photochemical bis-germylation of C-60 with digermirane
T Akasaka; Y Maeda; T Wakahara; T Mizushima; W Ando; M Walchli; T Suzuki; K Kobayashi; S Nagase; M Kako; Y Nakadaira; M Fujitsuka; O Ito; Y Sasaki; K Yamamoto; T Erata
ORGANIC LETTERS, AMER CHEMICAL SOC, 2, 17, 2671-2674, Aug. 2000, Peer-reviwed, [GRAPHICS]
In the photochemical bis-germylation of C-60 with 1,1,2,2-tetrakis(2,6 diethylphenyl)-1,2-digermirane (1), a cycloadduct (2) is obtained in high yield for the first time. Spectroscopic analysis and theoretical investigation confirm that 2 (which has C-1 symmetry) results from 1,4-cycloaddition. Control experiments and laser flash photolysis experiments suggest that an exciplex intermediate is responsible for the formation of 2. The redox properties of 2 were examined by differential pulse voltammetry.
Scientific journal, English - Silylene-transfer Reactions of Cyclic Organosilanes Induced by Phenanthraquinone Triplet
M. Kako; M. Ninomiya; M. Gu; M. Mori; Y. Nakadaira; M. Wakasa; H. Hayashi
Chemical Communications, 450, Jul. 2000, Peer-reviwed
International conference proceedings, English - Structures and ionization energies of some bis- and tris(3,4-dimetala-1-butyne-1,4-diyl)s containing group 14 elements as key metal atoms: Tetragermacycloocta-1,5-diyne, hexasilacyclododeca-1,5,9-triyne, hexagermacyclododeca-1,5,9-triyne, and related compounds
Y Nakadaira; H Komoriya; S Kakuma; M Kako; K Mochida; M Yasui; F Iwasaki; M Shimoda; F Matsumoto; M Yashikawa
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, CHEMICAL SOC JAPAN, 73, 6, 1403-1408, Jun. 2000, Peer-reviwed, By X-ray crystallographic analysis, the molecular structure of 3,4,7,8-tetragermacycloocta-1,5-diyne 1b has been established to be planar and quite similar to that of silicon analog 3,4,7,8-tetrasilacycloocta-1,5-diyne 1a. The detailed comparison of structures of cyclic acetylene analogs including a group 14 element shows that ring strain induced by the ethynylene units may be released in a different manner by the carbocycle and by its group 14 metalloid analogs. In contrast to cycloocta-1,5-diynes, structures of the higher homologs, 3,4,7,8,11,12-hexasilacyclododeca-1,5,9-triyne 2a and 3,4, 7,8,11,12-hexagermacyclododeca-1,5,9-triyne 2b were determined by X-ray crystallographic analyses to adopt a chair-like conformation. Ionization energies of these 3,4-dimetala-1-butyne-1,4-diyls in condensed phase were obtained by photoelectron spectroscopic methods.
Scientific journal, English - Photoinduced electron-transfer reaction between C-60 and cyclic silicon compounds
Y Sasaki; T Konishi; M Fujitsuka; O Ito; Y Maeda; T Wakahara; T Akasaka; M Kako; Y Nakadaira
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA, 599, 2, 216-220, Apr. 2000, Peer-reviwed, Electron transfer from cyclic silicon compounds to photo-excited C-60 in polar solvents has been investigated by laser photolysis with observation of the transient absorption bands in the near-IR region. For three-, four- and five-membered cyclic silicon compounds in benzonitrile, the rise of the radical anion of C-60 [C-60(.-)] was observed with the rapid decay of the triplet state of C-60 [C-3(60)*], indicating that electron transfer takes place via C-3(60)*. The rate constant (k(et)) and quantum yield (Phi(et)) of electron transfer decrease with an increase in the number of silicon units. The k(et) and Phi(et) values of the cyclic silicon compounds are smaller than those of the corresponding cyclic germanium compounds; an especially prominent difference was observed for four-membered cyclic compounds. (C) 2000 Elsevier Science S.A. All rights reserved.
Scientific journal, English - Metal-free Bis-germylation: C60-Sensitized Reaction of Digermirane with Benzonitrile
Y. Maeda; S. Takahashi; T. Wakahara; T. Akasaka; Y. Sasaki; M. Fujitsuka; O. Ito; K. Kobayashi; S. Nagase; M. Kako; Y. Nakadaira
ITE Letters on Batteries, New Technologies & Medicine, 1, 408-411, 2000, Peer-reviwed
Scientific journal, English - Novel metal-free bis-silylation: C-60-sensitized reaction of disilirane with benzonitrile
T Akasaka; Y Maeda; T Wakahara; M Okamura; M Fujitsuka; O Ito; K Kobayashi; S Nagase; M Kako; Y Nakadaira; E Horn
ORGANIC LETTERS, AMER CHEMICAL SOC, 1, 10, 1509-1512, Nov. 1999, Peer-reviwed, [GRAPHICS]
The photochemical reaction of disilirane with C-60 in benzonitrile affords the adduct of disilirane and benzonitrile as a bis-silylated product. In this reaction, C-60 serves as a sensitizer. The results are reasonably accounted for by a novel metal-free bis-silylation of an unsaturated compound via a photoinduced electron-transfer process.
Scientific journal, English - Endohedrally metal-doped heterofullerenes: La@C81N and La-2@C79N
T Akasaka; S Okubo; T Wakahara; K Yamamoto; K Kobayashi; S Nagase; T Kato; M Kako; Y Nakadaira; Y Kitayama; K Matsuura
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 9, 945-946, Sep. 1999, Peer-reviwed, The first evidence of the gas-phase formation of endohedrally La-doped azafullerene ions La@C81N+ and La-2@C79N+ was obtained by the fast atom bombardment mass (FABMS) fragmentation of the adducts, La@C-82(NCH2Ph) and La-2@C-80(NCH2Ph).
Scientific journal, English - Reactions of vinyldisilanes with ruthenium carbonyl
XS Dai; N Kano; M Kako; Y Nakadaira
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 8, 717-718, Aug. 1999, Peer-reviwed, Reaction of beta-styrylpentamethyldisilane (1a) with Ru-3(CO)(12) afforded beta-styryltrimethylsilane (2a) with elimination of a dimethylsilylene unit, while under similar conditions alpha-isomer 1b yielded 2a together with 1a. Studies on these reactions suggest the formation of silapropenyl and silylene ruthenium complexes as key intermediates.
Scientific journal, English - Photophysical and photochemical properties of bis-silylated C-60 derivatives
M Fujitsuka; O Ito; Y Maeda; M Kako; T Wakahara; T Akasaka
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ROYAL SOC CHEMISTRY, 1, 15, 3527-3531, Aug. 1999, Peer-reviwed, Photophysical and photochemical properties of bis-silylated C-60 derivatives have been examined using steady-state and time-resolved spectroscopies. Absorption band edges of 1,2- and 1,4-bis-silylated C-60 derivatives ranged to about 800 nm. Fluorescence quantum yields of 1,2- and 1,16-adducts were slightly larger than that of C-60, while 1,4-adducts did not show fluorescence. By laser irradiation to the bis-silylated C-60 derivatives, transient absorption bands due to their triplet excited states were confirmed in the visible and near-IR regions. Photoinduced electron transfer from electron donor to excited triplet states of bis-silylated C-60 derivatives was also confirmed in transient absorption spectra. The acceptor-abilities of the excited triplet states changed with the position of the C-60-silicon bonds, which can be explained mainly on the basis of reduction potentials and triplet energies of the bis-silylated C-60 derivatives.
Scientific journal, English - The silylfullerenes
T. Akasaka; Y. Maeda; T. Kondo; T. Wakahara; T. Suzuki; K. Kobayashi; S. Nagase; M. Kako; Y. Nakadaira
85, May 1999
International conference proceedings, English - Photoinduced electron-transfer reaction of 7,8-disilabicyclo[2.2.2]octa-2,5-dienes
M Kako; K Hatakenaka; S Kakuma; M Ninomiya; Y Nakadaira; M Yasui; F Iwasaki; M Wakasa; H Hayashi
TETRAHEDRON LETTERS, PERGAMON-ELSEVIER SCIENCE LTD, 40, 6, 1133-1136, Feb. 1999, Peer-reviwed, 9,10-Dicyanoanthracen-sensitized irradiation of 7,8-di silabicyclo[2.2.2]octa-2,5-dienes 1-3 in the presence of MeOH resulted in the formation of dimethoxydisilanes and the corresponding aromatic compounds. A stepwise mechanism involving C-Si bond cleavage by MeOH is proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.
Scientific journal, English - Reactions of vinyldisilanes with ruthenium carbonyl
Xiaosu Dai; Naokazu Kano; Masahiro Kako; Yasuhiro Nakadaira
Chemistry Letters, Chemical Society of Japan, 8, 717-718, 1999, Reaction of β-styrylpentamethyldisilane (1a) with Ru3(CO)12 afforded β-styryltrimethylsilane (2a) with elimination of a dimethylsilylene unit, while under similar conditions α-isomer 1b yielded 2a together with 1a. Studies on these reactions suggest the formation of silapropenyl and silylene ruthenium complexes as key intermediates.
Scientific journal, English - Reactions of vinyldisilanes with ruthenium carbonyl
Xiaosu Dai; Naokazu Kano; Masahiro Kako; Yasuhiro Nakadaira
Chemistry Letters, Chemical Society of Japan, 8, 717-718, 1999, Reaction of β-styrylpentamethyldisilane (1a) with Ru3(CO)12 afforded β-styryltrimethylsilane (2a) with elimination of a dimethylsilylene unit, while under similar conditions α-isomer 1b yielded 2a together with 1a. Studies on these reactions suggest the formation of silapropenyl and silylene ruthenium complexes as key intermediates.
Scientific journal, English - Photochemical bissilylation of C-60 with disilane
T Akasaka; T Suzuki; Y Maeda; M Ara; T Wakahara; K Kobayashi; S Nagase; M Kako; Y Nakadaira; M Fujitsuka; O Ito
JOURNAL OF ORGANIC CHEMISTRY, AMER CHEMICAL SOC, 64, 2, 566-569, Jan. 1999, Peer-reviwed, The photochemical reaction of C-60 with disilane I affords the adduct 2 as a bissilylated product. The unique redox properties of 2 are reported by means of differential pulse voltammetry. The compound 2 was characterized by NMR, IR, and UV-vis spectroscopies. Spectroscopic and theoretical investigation strongly support the 1,16-addition structure having C-2 symmetry which results from addition at the 1,16 positions in C-60 The results are reasonably accounted for by the generation of a silyl radical which is responsible for the formation of 2.
Scientific journal, English - Charge transfer complexes and electron transfer reaction of organosilicon and related compounds
M Kako; Y Nakadaira
COORDINATION CHEMISTRY REVIEWS, ELSEVIER SCIENCE SA, 176, 87-112, Sep. 1998, Peer-reviwed, Charge transfer absorptions of linear oligosilanes and silanorbornadienes, charge transfer induced oligomerization, polymerization and cycloaddition of tetrasilacyclooctadiyne and its germanium analogues are described. Photo-induced electron transfer reactions of various types of organosilicon compounds are discussed in detail, and include photo-induced chlorinative Si-Si bond cleavage, photo-induced nucleophilic Si-Si bond cleavage, fluorinative Si-Si bond cleavage via electron transfer, skeletal rearrangement via photo-induced electron transfer and the structure of a silyl radical cation. (C) 1998 Elsevier Science S.A. All sights reserved.
Scientific journal, English - Optical characteristics of ultrathin oligosilane films prepared by molecular beam deposition method
D Sasaki; H Tada; K Ishida; T Horiuchi; K Matsushige; T Endo; M Kako; Y Nakadaira
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, JAPAN J APPLIED PHYSICS, 37, 8A, L953-L955, Aug. 1998, Peer-reviwed, In order to investigate the correlation between the molecular orientation and the optical characteristics of ultrathin films of permethyl-dodecasilane, CH3{Si(CH3)(2)}(12)CH3 (DM12), we grew the films on quartz, KBr and KCl by molecular beam deposition, and characterized them by optical absorption, photoluminescence (PL), and photoexcitation spectroscopy and atomic force microscopy. We found that DM12 molecules formed a monolayer on quartz with their molecular chains' perpendicular to the surface, while DM12 films grew on KBr and KCl with their molecular axis oriented parallel to the surfaces. These films exhibited quite different absorption spectra as a result of their molecular orientation and the interaction between molecules. The PL spectra obtained for the films on quartz and KBr were, however, almost the same, indicating that the origin of the luminescence was the localized states such as defects on the chains.
Scientific journal, English - Endohedrally metal-doped heterofullerenes
T Akasaka; S Okubo; T Wakahara; K Kobayashi; S Nagase; M Kako; Y Nakadaira; T Kato; K Yamamoto; H Funasaka; K Matsuura
RECENT ADVANCES IN THE CHEMISTRY AND PHYSICS OF FULLERENES AND RELATED MATERIALS, VOL 6, ELECTROCHEMICAL SOCIETY INC, 98, 8, 1003-1007, 1998, Peer-reviwed, The first evidence of the gas-phase formation of endohedrally La-doped azafullerene ions La-2@C79N+ and La@C81N+ is obtained. It is found that these ions are efficiently formed by the fast atom bombardment mass (FABMS) fragmentation of the adducts of the reactions of benzyl azide with La-2@C-80 and La@C-82. Ab initio calculations show that the neutral molecules La-2@C79N and La@C81N are less reactive toward dimerization and abstraction than azafullerenes themselves, because they contain La atoms inside the cages.
International conference proceedings, English - C-13 and La-139 NMR studies of La-2@C-80: First evidence for circular motion of metal atoms in endohedral dimetallofullerenes
T Akasaka; S Nagase; K Kobayashi; M Walchli; K Yamamoto; H Funasaka; M Kako; T Hoshino; T Erata
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH, WILEY-V C H VERLAG GMBH, 36, 15, 1643-1645, Aug. 1997, Peer-reviwed
Scientific journal, English - Photo-induced silylene-transfer reactions of cyclic organosilanes to phenanthraquinone
M Kako; M Ninomiya; Y Nakadaira
CHEMICAL COMMUNICATIONS, ROYAL SOC CHEMISTRY, 15, 1373-1374, Aug. 1997, Peer-reviwed, Cophotolysis of cyclic organosilanes 1-4 with phenanthraquinone gave silylene insertion products via radical displacement at the silicon atoms of organosilanes by the photochemically excited phenanthraquinone.
Scientific journal, English - Silacyclopentadienylidene, the first silylene incorporated in a silole ring
M Kako; S Oba; R Uesugi; S Sumiishi; Y Nakadaira; K Tanaka; T Takada
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, ROYAL SOC CHEMISTRY, 7, 1251-1253, Jul. 1997, Peer-reviwed, Silacyclopentadienylidene 1 was generated photochemically using 7-silanorbornadiene and norbornene precursors and observed in frozen hydrocarbon matrices at 77 K.
Scientific journal, English - Electron-transfer reaction of 1,2-disila-3,5-cyclohexadienes
M Kako; H Takada; Y Nakadaira
TETRAHEDRON LETTERS, PERGAMON-ELSEVIER SCIENCE LTD, 38, 20, 3525-3528, May 1997, Peer-reviwed, Photolysis of 1,2-disila-3,5-cyclohaxadienes 1a-b in the presence of methylene blue as a sensitizer led to efficient formation of the corresponding siloles as ring contraction products. The reaction mechanism is best rationalized by electron-transfer from 1a-b to the excited state of methylene blue. Semiempirical molecular orbital calculation was also carried out to characterize the geometric and electronic structure of radical cation 1a(+.). (C) 1997 Elsevier Science Ltd.
Scientific journal, English - Charge-transfer complex formation and photo-induced electron-transfer reaction of dibenzo-7-silabicyclo[2.2.1]hepta-2,5-dienes
M Kako; M Mori; K Hatakenaka; S Kakuma; Y Nakadaira; M Yasui; F Iwasaki
TETRAHEDRON, PERGAMON-ELSEVIER SCIENCE LTD, 53, 4, 1265-1274, Jan. 1997, Peer-reviwed, Dibenzo-7-silabicyclo[2.2.1]hepta-2,5-dienes (1a, 1b) are excellent electron donors because of effective sigma-pi conjugation between the orbitals of C-C pi bonds and Si-C sigma bonds. Some of their donor properties are demonstrated by the reactions with some electron accepters. When la and Ib are mixed with tetracyanoethylene, facile formation of charge-transfer complexes was observed. In the 2,4,6-triphenylpyrylium tetrafluoroborate-sensitized photoreaction of Ib, the corresponding difluorosilane and anthracene were obtained in good yields. The structural and electronic features of radical cation 1a(+.) were provided by semiemperical molecular orbital calculation. In addition, the structure of la in crystals was determined by X-ray crystallography and compared with that obtained by the calculation. (C) 1997, Elsevier Science Ltd.
Scientific journal, English - Synthesis and properties of a strained germacycle having a Ge-Ge bond, 3,4-benzo-1,1,2,2-tetraethyl-1,2-digermacyclobut-3-ene
H Komoriya; M Kako; Y Nakadaira
ORGANOMETALLICS, AMER CHEMICAL SOC, 15, 8, 2014-2018, Apr. 1996, Peer-reviwed, A new strained germacycle, 3,4-benzo-1,1,2,2-tetraethyl-1,2-digermacyclobut-3-ene (1), was prepared by treatment of 1,2-bis(chlorodiethylgermyl)benzene with sodium in toluene. At ambient temperature, 1 was gradually oxidized in air to give 3,4-benzo-1,3-digerma-2-oxaeyclopent-4-ene (2), and in the presence of sulfur, 1 was converted to 3,4-benzo-1,3-digerma-2-thiacyclopent-4-ene (3), quantitatively under similar thermal conditions. The digermacyclobutene 1 was thermally labile and readily underwent ring-opening polymerization in toluene to give the corresponding polymer 4 (M(w) = 4.4 x 10(5), M(w) = 7.4 x 10(5), M(w)/M(n) = 1.7). On thermolysis at 160 degrees C for 20 h, 1 gave two products, 4,5-benzo-1,2,3-trigennacyclopent-4-ene (5) and 3,4:6,7-dibenzo-1,2,5-trigermacyclohepta-3,6-diene (6), in reasonable yields. On the other hand, the thermolysis of 1 in the presence of phenylacetylene gave 2,3-benzo-1,4-digerma-5-phenyl-cyclohexa-2,5-diene (7), quantitatively. Further, 1 was thermolyzed in CCl4 to give two chlorinated products, 1,2-bis(chlorodiethylgermyl)benzene (9) and 1-(chlorodiethylgermyl)-2-(diethyl(trichloromethyl)germyl)benzene (10), in reasonable yields. The reaction mechanisms for the polymerization and the thermolysis are discussed.
Scientific journal, English - ELECTRONIC-PROPERTIES, POLYMERIZATION, AND CYCLOADDITION OF 3,4,7,8-TETRAGERMACYCLOOCTA-1,5-DIYNE AND RELATED-COMPOUNDS
H KOMORIYA; M KAKO; Y NAKADAIRA; K MOCHIDA; M TONOGAKIKUBOTA; T KOBAYASHI
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA LAUSANNE, 499, 1-2, 123-129, Sep. 1995, Peer-reviwed, Permethylated 3,4,7,8-tetragermacycloocta-1,5-diyne (1) and 3,3-disila-7,8-digermacycloocta-1,5-diyne (2) were prepared. The photoelectron spectra of 1 and 2 were compared with that of their tetrasila analogue 3. The first ionization energy decreases in the order 3>2>1. Charge-transfer spectra of 1-tetracyanoethylene (TCNE), 2-TCNE and 3-TCNE complexes were observed. In CH2Cl2 containing TCNE 1 underwent oligomerization to give its higher homologues, and in CH3CN containing a catalytic amount of TCNE both 1 and 2 were polymerized to give the corresponding polymers almost quantitatively, whereas the sila analogue 3 was stable under these conditions. All compounds 1, 2 and 3 cycloadded to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to give the corresponding 1:1 adducts in a [2 + 6] manner.
Scientific journal, English - REARRANGEMENT OF SILANORBORNADIENES VIA PHOTOINDUCED ELECTRON-TRANSFER
M KAKO; S KAKUMA; K HATAKENAKA; Y NAKADAIRA; M YASUI; F IWASAKI
TETRAHEDRON LETTERS, PERGAMON-ELSEVIER SCIENCE LTD, 36, 35, 6293-6296, Aug. 1995, Peer-reviwed, Irradiation of silanorbornadienes 1 using 9,10-dicyanoanthracene as a sensitizer afforded two isomers 2 and 3 accompanied with anthracene. In the presence of molecular oxygen, dioxide 5 was obtained as an additional product These reactions are explained in terms of the initial electron donor-acceptor interaction followed by skeletal rearrangement.
Scientific journal, English - TETRACYANOETHYLENE-INDUCED CHLORINATIVE CLEAVAGE OF PERMETHYLATED OLIGOGERMANES WITH POLYHALOMETHANES
K MOCHIDA; R HATA; C HODOTA; S FUKUZUMI; M KAKO; Y NAKADAIRA
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 3, 245-245, Mar. 1995, Peer-reviwed, In the presence of tetracyanoethylene (TCNE), Ge-Ge bonds of oligogermanes (Me(Me(2)Ge)(n)Me, n=2-5) were cleaved with CCl4 to yield the corresponding chlorogermanes. A mechanism involving an oligogermane radical cation is proposed for the Ge-Ge cleavage.
Scientific journal, English - PHOTOCHEMICAL ISOMERIZATION OF 1-GERMA-2,4-CYCLOHEXADIENES
K MOCHIDA; C NOHARA; T OHHORI; M KAKO; Y NAKADAIRA
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 10, 1961-1962, Oct. 1994, Peer-reviwed, Tetraphenylgermacyclohexadiene photochemically isomerized to the 4-vinyl-germacyclobutene. In contrast, diphenylgermacyclohexadiene remained unchanged on irradiation in benzene, but in the presence of methanol it was converted to the methoxy-germane probably through the 1-germahexatriene intermediate.
Scientific journal, English - PREPARATION AND PROPERTIES OF 3,4,7,8-TETRAGERMACYCLOOCTA-1,5-DIYNE AND RELATED-COMPOUNDS
H KOMORIYA; M KAKO; Y NAKADAIRA; K MOCHIDA; M TONOGAKIKUBOTA; T KOBAYASHI
CHEMISTRY LETTERS, CHEMICAL SOC JAPAN, 8, 1439-1442, Aug. 1994, Peer-reviwed, Permethylated 3,4,7,8-tetragermacycloocta-1,5-diyne (1) and 3,4-disila-7,8-digermacycloocta-1, 5-diyne (2) were prepared. The photoelectron spectra of 1 and 2 were compared with that of their tetrasila-analog 3. The first ionization potential decreases in the order of 3, 2, and 1. Charge-transfer spectra of 1-teracyanoethylene (TCNE), 2-TCNE and 3-TCNE complexes were observed. Only 1 was oligomerized in the presence of TCNE to give its higher homologues. All 1, 2, and 3 cycloadded to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to give the corresponding 1:1 adducts in a [2+6] manner.
Scientific journal, English - Photochemical Reactions of cf3-substituted benzenes with tetraalkylated group 14 organometals
Yasuhiro Nakadaira; Michihiko Kawasaki; Da-Yang Zhou; Masahiro Kako
Main Group Metal Chemistry, 17, 8, 553-558, 1994, Peer-reviwed, Co-photolysis of a CF3-substituted benzene 1 and tetrabutylstannane in cyclohexane results in mainly butylation at the benzylic position with extrusion of one fluorine atom of the CF3 group accompanied by ring butylation as a minor path. On the other hand, the co-photolysis of 1 with tetrabutyl-germane and -silane in acetonitrile causes fluorinative cleavage of the σ-M-C bond to yield tributylfluoro-germane, and -silane, respectively, as main products. However, the butylated benzenes are detected only in trace amounts. © 1994, Walter de Gruyter. All rights reserved.
Scientific journal, English - 1,1-DIMESITYL-1-SILACYCLOPENTA-2,4-DIENE - A STABLE CARBON-UNSUBSTITUTED SILOLE
M KAKO; S OBA; Y NAKADAIRA
JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER SCIENCE SA LAUSANNE, 461, 1-2, 173-175, Nov. 1993, Peer-reviwed, 1,1-Dimesityl-1-silacyclopenta-2,4-diene a stable carbon-unsubstituted silole, has been prepared by the dehydration of 1,1-dimesityl-1-silacyclopent-4-en-3-ol. Also described are the reactions of the titled compound with maleic anhydride, triazolinedione and diiron nonacarbonyl.
Scientific journal, English - PHOTOINDUCED NOVEL SILYLATION OF CF-3-SUBSTITUTED BENZENES WITH DISILANE AND TRISILANE
M KAKO; T MORITA; T TORIHARA; Y NAKADAIRA
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, ROYAL SOC CHEMISTRY, 8, 678-680, Apr. 1993, Peer-reviwed, Irradiation of CF3-Substituted benzene in the presence of hexamethyldisilane and octamethyltrisilane causes two types of photosilylation, namely one at a benzylic position to give the corresponding benzylic silanes, and the other at aromatic ring to afford the corresponding phenylsilanes.
Scientific journal, English - Reaction of singlet oxygen with disiliranes: Dioxygen insertion into Si-Si σ bonds
W. Ando; M. Kako; T. Akasaka; S. Nagase
Organometallics, 12, 5, 1514-1522, 1993, Peer-reviwed
English - CYCLOREVERSION OF 2,3-DISILABICYCLO[2.2.2]OCTA-5,7-DIENES INDUCED BY ELECTRON-TRANSFER
Y NAKADAIRA; Y GOMI; H HOSOE; S KYUSHIN; M KAKO; K HATAKENAKA; M OHASHI
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, CHEMICAL SOC JAPAN, 66, 1, 344-346, Jan. 1993, Peer-reviwed
Scientific journal, English - PHOTOINDUCED ELECTRON-TRANSFER OXYGENATION OF 1,2-DISILETENE
T AKASAKA; K SATO; M KAKO; W ANDO
TETRAHEDRON, PERGAMON-ELSEVIER SCIENCE LTD, 48, 16, 3283-3292, Apr. 1992, Peer-reviwed, Photo-induced electron transfer oxygenation of 3-phenyl-1,1,2,2-tetramesityl-1,2-disilet-3-ene (1) in acetonitrile-methylene chloride afforded the corresponding 1,2-dioxa-3,6-disilin (2) in moderate yield as a dioxygen insertion product into a silicon-silicon sigma-bond together with 1-oxa-2,5-disilolene (3). The results are reasonably accounted for by an electron transfer from disiletene 1 to the excited singlet state of the sensitizer to form a radical ion pair followed by addition of oxygen. Interestingly, a remarkable solvent effect was observed in the product ratio of dioxadisilin 2 and oxadisilolene 3 as a monooxygenated product. The solvent acetonitrile, acting as a nucleophile, participates for predominant formation of 2. Meanwhile, in the absence of acetonitrile, 3 was afforded as a major product. The conceivable mechanism is proposed.
Scientific journal, English - FORMATION OF 1,2,3,6-DIOXADISILIN IN PHOTOINDUCED ELECTRON-TRANSFER OXYGENATION OF 1,2-DISILETENE
T AKASAKA; K SATO; M KAKO; W ANDO
TETRAHEDRON LETTERS, PERGAMON-ELSEVIER SCIENCE LTD, 32, 45, 6605-6608, Nov. 1991, Peer-reviwed, Photo-induced electron transfer oxygenation of 3-phenyl-1,1,2,2-tetramesityl-1,2-disiletene(1) in acetonitrile-methylene chloride afforded the corresponding 1,2,3,6-dioxadisilin (2) in moderate yield as a dioxygen insertion product into a silicon-silicon sigma-bond together with 1,2,5-oxadisilolene (3). The results are reasonably accounted for by an electron transfer from disiletene 1 to the excited singlet state of the sensitizer to form a radical ion pair followed by addition of oxygen.
Scientific journal, English - "Direct Observation of the Azetidinium Imide Intermediate in the [σ2+π2] addition of 1,24-Triazoline-3,5-dione to Disiliranes"
Journal of the American Chemical Society, 113, 16, 1991
English - SPECTROSCOPIC STUDIES ON CHARGE-TRANSFER PHOTOOXYGENATION OF DISILIRANES
T AKASAKA; M KAKO; S NAGASE; A YABE; W ANDO
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 112, 21, 7804-7806, Oct. 1990
English - SINGLET OXYGENATION OF OXADISILIRANES - SYNTHESES AND CRYSTAL-STRUCTURE OF 1,2,4,3,5-TRIOXADISILOLANES
W ANDO; M KAKO; T AKASAKA; Y KABE
TETRAHEDRON LETTERS, PERGAMON-ELSEVIER SCIENCE LTD, 31, 29, 4177-4180, 1990, Peer-reviwed
Scientific journal, English - Formation of 1,2-dioxolane in the singlet oxygenation of a silicon-silicon σ-bond: peroxonium ion intermediate
W. Ando; M. Kako; T. Akasaka; S. Nagase; T. Kawai; Y. Nagai; T. Sato
Tetrahedron Letters, 30, 48, 6705-6708, 1989, Peer-reviwed
English - REACTION OF SINGLET OXYGEN WITH THIIRANE - PEROXYSULFENIC ACID INTERMEDIATE AS A NEW OXIDIZING SPECIES
T AKASAKA; M KAKO; H SONOBE; W ANDO
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMER CHEMICAL SOC, 110, 2, 494-496, Jan. 1988
Scientific journal, English
MISC
- Functionalization of Endohedral Metallofullerenes with Reactive Silicon and Germanium Compounds
Masahiro Kako; Shigeru Nagase; Takeshi Akasaka
Exohedral derivatization of endohedral metallofullerenes (EMFs) has been exploited as a useful method for characterizing the structural and chemical properties of EMFs, and for functionalizing them for potential applications. The introduction of heteroatoms, such as electropositive silicon atoms, to fullerene cages is a novel functionalization method that remarkably affects the electronic characteristics of fullerenes. This review comprehensively describes the results of the reactions of monometallofullerene, dimetallofullerene, and trimetallic nitride template EMFs with disilirane, silirane, silylene, and digermirane, which afforded the corresponding silylated and germylated fullerenes. Several examples emphasize that exohedral functionalization regulates the dynamic behaviors of the encapsulated metal atoms and clusters in the fullerene cages. The electronic effects of silyl and germyl groups are represented by comparing the redox properties of silylated and germylated EMFs with those of other EMFs derivatized with carbon-atom-based functional groups., MDPI AG, Jul. 2017, MOLECULES, 22, 7, 1179-1195, English, Peer-reviwed, Invited, Book review, 1420-3049, WOS:000406621300153 - Photochemical cycloaddition of C76 with disilirane
Takatsugu Wakahara; Aihong Han; Yutaka Maeda; Yasuyuki Niino; Takeshi Akasaka; Kazunori Yamamoto; Masahiro Kako; Yasuhiro Nakadaira; Kaoru Kobayashi; Shigeru Nagase
2001, ITE Letters on Batteries, New Technologies & Medicine, 2, 649-652 - 13C and 139La NMR Study of La2@C80. The First Ecidence for Circular Motion of Metal Atoms in Endohedral Dimetallofullerene
AKASAKA T; NAGASE S; KOBAYASHI K; WAELCHLI M; YAMAMOTO K; FUNASAKA H; KAKO M; HOSHINO T; ERATA T
1997, Angewavdte Chemie, International Edition in English, 36, 15, 1643-1645, 1433-7851 - Electron Transfer Oxygenation of Oxadisiliranes
Wataru Ando; Masahiro Kako; Takeshi Akasaka
1993, Chemistry Letters, 10, 1679-1682, 0366-7022 - DIRECT OBSERVATION OF AN AZETIDINIUM IMIDE INTERMEDIATE IN [PI(2) + SIGMA(2)] ADDITION OF 1,2,4-TRIAZOLINE-3,5-DIONE TO DISILIRANE
W ANDO; M KAKO; T AKASAKA
AMER CHEMICAL SOC, Jul. 1991, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 113, 16, 6286-6288, English, Introduction scientific journal, 0002-7863, WOS:A1991FZ53300064
Lectures, oral presentations, etc.
- Photoreactions of Sc3N@Ih-C80 and Lu3N@Ih-C80 with Disilirane: Characterization of Labile 1,2-Adducts
S. Kanzawa; F. Ozeki; S. Fukazawa; M. Kako; K. Sato; M. Yamada; Y. Maeda; M. Furukawa; T. Akasaka
Poster presentation, English, The 56th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Mar. 2019 - Photoreaction of Sc3N@Ih-C80 with Disilirane: Formation and Isomerization of 1,2-, 1,3-, and 1,4-Adducts
S. Fukazawa; Y. Sato; M. Kako; M. Yasui; M. Yamada; Y. Maeda; T. Akasaka
Poster presentation, English, The 54th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Mar. 2018 - Photoreactions of Cyclic Organosilanes with Trimetallic Nitride Template Endohedral Metallofullerenes
S. Fukazawa; T. Sugiura; K. Miyabe; M. Kako; T. Akasaka
Poster presentation, English, The 52nd Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2017 - Photochemical Addition of Siliranes to Sc3N@Ih-C80: Interconversion of the [6,6]- and [5,6]-Adducts
T. Sugiura; K. Miyabe; M. Kako; M. Yasui; M. Yamada; Y. Maeda; J. Guo; S. Nagase; T. Akasaka
Poster presentation, English, The 52nd Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2017 - Photoreactions of Trimetallic Nitride Template Endohedral Metallofullerenes with Digermirane
K. Miyabe; Y. Sato; M. Kako; M. Yasui; K. Sato; N. Mizorogi; W.-W. Wang; S. Nagase; T. Akasaka
Poster presentation, English, The 50th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2016 - Preparation, Structural Determination, and Characterization of Electronic Properties of Carbosilylated Sc3N@Ih-C80
T. Sugiura; S. Fukazawa; K. Miyabe; M. Kako; M. Yasui; M. Yamada; M. Suzuki; Y. Maeda; T. Akasaka
Poster presentation, English, The 50th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2016 - Reactions of Endohedral Metallofullerenes with Silacyclopropanes: Mono-silylation and Carbosilylation of Lu3N@Ih-C80
K. Minami; M. Kako; K. Sato; N. Mizorogi; S. Nagase; T. Akasaka
Poster presentation, English, The 50th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2016 - Reactions of Trimetallic Nitride Template Endohedral Metallofullerenes with Silacyclopropanes
K. Minami; T. Sugiura; M. Kako; K. Sato; S. Nagase; T. Akasaka
Poster presentation, English, The 48th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2015 - Addition Reactions of Trimetallic Nitride Template Endohedral Metallofullerenes with Disilirane and Digermirane
K. Miyabe; M. Kako; K. Sato; M. Suzuki; N. Mizorogi; Y. Maeda; M. M. Olmsted; A. L. Balch; W.-W. Wang; S. Nagase; T. Akasaka
Poster presentation, English, The 48th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Feb. 2015 - Synthesis, Structural Determination and Characterization of Electronic Properties of Bis-Germylated Sc3N@Ih-C80 and Lu3N@Ih-C80
K. Miyabe; M. Kako; K. Sato; M. Suzuki; N. Mizorogi; Y. Maeda; M. M. Olmsted; A. L. Balch; W.-W. Wang; S. Nagase; T. Akasaka
Poster presentation, English, The 47th Fullerenes-Nanotubes-Graphene General Symposium, Domestic conference
Sep. 2014 - 不飽和化合物の光誘起電子移動型ビスシリル化反応
前田 優; 若原孝次; 赤坂 健; 藤塚 守; 伊藤 攻; 加固昌寛; 中平靖弘; 小林 郁; 永瀬 茂
Oral presentation, Japanese, 第45回有機金属化学討論会，PA108
Sep. 1998
Courses
- 基礎科学実験B2
Oct. 2024 - Mar. 2025 - 無機物質化学特論
Oct. 2024 - Mar. 2025 - 現代化学
Oct. 2024 - Mar. 2025 - 化学概論第二
Oct. 2024 - Mar. 2025 - 基礎化学実験
Nov. 2024 - 2025 - 化学結合と構造
Apr. 2024 - Sep. 2024 - 基礎科学実験B1
Apr. 2024 - Sep. 2024 - 化学概論第一
Apr. 2024 - Sep. 2024 - 基礎科学実験B
Apr. 2019 - Sep. 2024
電気通信大学 - 化学概論第一（クラス4）
Apr. 2021 - Mar. 2024
電気通信大学 - 現代化学
Oct. 2019 - Mar. 2024
The University of Electro-Communications - 現代化学
Oct. 2019 - Mar. 2024
電気通信大学 - 化学概論第二
Oct. 2019 - Mar. 2024
The University of Electro-Communications - 基礎化学実験
Oct. 2019 - Mar. 2024
The University of Electro-Communications - 無機物質化学特論
Oct. 2019 - Mar. 2024
The University of Electro-Communications - 現代化学
Oct. 2019 - Mar. 2024
電気通信大学 - 化学概論第二
Oct. 2019 - Mar. 2024
電気通信大学 - 基礎化学実験
Oct. 2019 - Mar. 2024
電気通信大学 - 基礎科学実験B
Apr. 2019 - Mar. 2024
電気通信大学 - 化学概論第一（クラス4）
Apr. 2021 - Sep. 2023
The University of Electro-Communications - 化学概論第一
Apr. 2019 - Sep. 2023
電気通信大学 - 化学結合と構造
Apr. 2019 - Sep. 2023
The University of Electro-Communications - 化学結合と構造
Apr. 2019 - Sep. 2023
電気通信大学 - 基礎科学実験B
Apr. 2019 - Sep. 2023
電気通信大学 - 現代化学
The University of Electro-Communications - K課程総合コミュニケーション科学
The University of Electro-Communications - K課程総合コミュニケーション科学
電気通信大学 - Chemistry Laboratory
The University of Electro-Communications
Affiliated academic society
Research Themes
- Creation of Molecular Functionalization of Endohedral Metallofullerene and Its Function
赤阪 健; 加固 昌寛; 前田 優; 山田 道夫; 鈴木 光明
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Foundation for Advancement of International Science, Grant-in-Aid for Scientific Research (C), 次世代を切り拓く革新的な電子・光・磁気機能を有する物質の創出を図るため、分子エレクトロニクス素子や単一分子デバイスをはじめ、磁気的、光学的機能材料としてのナノカーボンが注目され、その基礎および応用研究が精力的に展開されている。本研究では、最も特異な構造と電子的特性を有するナノカーボンの一つである金属内包フラーレンに着目し、元素化学に基づく選択的分子変換による新しい構造や電子的特性を有する分子の創出を図った。これまで金属内包フラーレンの生成量が少なく分離精製が困難であったことから、限られた研究しか行われていなかったが、申請者らが開発した大量分離法がブレークスルーとなり、困難とされていた金属内包フラーレンの化学修飾に関する研究を行える環境が整ったので金属内包フラーレンの分子変換法の開拓の一環として、金属内包フラーレンの光電変換材料としての有用性を発現させるために溶解性の向上とその電子的特性の制御を目的とした。これらの化学は他に例のない全く独創的な研究であり、フラーレン化学の単なる一分野の開拓のみならず、金属内包フラーレンを新しいナノカーボン材料科学へと導くものであり、本研究がもたらす新しい領域への貢献及び波及効果は大きいと信じる。本研究では、金属内包フラーレンの電子的特性や反応性の解明を行うと共に元素化学に基づく分子変換による種々の誘導体合成を遂行した。, 20K05469
01 Apr. 2020 - 31 Mar. 2023 - Creation of functionalized endohedral metallofullerenes and its function
Akasaka Takeshi
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Foundation for Advancement of International Science, Grant-in-Aid for Scientific Research (C), Chemical research into the synthesis, characterization, and functionalization of compounds with π-electron systems, as typified by fullerenes and endofullerenes, is showing steady progress, and the momentum of this area is rising on new evolution. Through the investigation on the reactive nanocarbons, we focused on the unique characteristics of endohedral metallofullerenes that give functionalized molecules with a diverse range of structural and functional variations, when we attempt to construct highly elaborated π-systems with more sophisticated and complex orders and functionality., 17K05797
01 Apr. 2017 - 31 Mar. 2020 - Synthesis and Characterization of Some Three Dimensional Cyclic Organosilanes
NAKADAIRA Yasuhiro; KAKO Masahiro
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, The University of Electro-Communications, Grant-in-Aid for Scientific Research (C), The emission from the porous silicon has not fully explained yet. Here, in order to take one of possible chemical approaches to clarify the essential structure of the emission of this kind, we have planned to synthesize and characterize some caged solid organosilanes having both silicon-silicon and silicon-oxygen-silicon bonds. Tow types of tetrameric caged polysiloxanes containing silicon-silicon bonds have been prepared by condensation of 1,2- dimethyl-1,1,2,2-tetraethoxy disilane under acidic conditions. They show UV absorption maxima at 235 and 229 nm, respectively. At the same time, they emit as expected at 360 and 351 nm with quantum yields of 0.13 and O.11 respectively. These emissive properties are comp ared with those of two-dimensional analogues and this indicates that such a rigid three-dimensional structure having both silicon-silicon and silicon-oxy gen-silicon bonds should be essential for the efficient emission observed. Then, to examine the substituent effect on the emission, we have prepared the same types of caged polysiloxane with isopropyl groups instead of methyl groups by condensation of 1,2-diisopropyl-1,1,2,2- tetraethoxy disilane under similar acidic conditions. They show UV absorptions at longer wavelength, 256 and 242 nm, respectively, and give the emission maxima at 361 and 350 nm, respectively, with poor quantum efficiency, namely, 0.067 and 0.034, respectively. Phenyl derivatives have been also prepared starting from hydrolysis of 1,2-diphenyl-1,1,2,2- tetrachlorodisilane in aqueous acetone., 11640527
1999 - 2000 - 環状共役14族元素2価活性種と2量体の合成
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 特定領域研究(A), 2配位ケイ素原子、すなわちシリレン単位を環内に含む新規な環状共役2配位ケイ素化学種、シラシクロペンタジエニリデンを合成してその反応性、さらに理論的立場からその構造および電子状態に検討を加え、これが反芳香族4π電子系化合物であることを明らかにした。今回、この高周期同族体である環状共役ゲルミレン、すなわちゲルマシクロペンタジエニリデン1を発生させ、その反応性を検討した。前駆体と期待されるゲルマノルボルナジエン誘導体4を得るために、スピロ型ビスゲルモールにシクロオクチンをDiels-Alder反応させた。しかし、対応するシロール誘導体の場合と異なり、恐らく4が極めて熱的に不安定なため、本反応ではその分解生成物であるテトラフェニルベンゼン7が得られたのみであった。そこで、この反応過程で1が実際に発生していることを確認するために、同反応条件下捕捉剤o-キノン5を存在させて反応を行った。その結果、期待される捕捉生成物6が7とともに得られた。6は対応する1,1-ジクロロゲルモールとカテコールから別途合成した標品と一致した。次に分子内に、ジシラゲルマン単位を有する9,9-ジシラ-9-ゲルマフルオレン8を合成し、その光分解による9-ゲルマフルオロニリデン2の生成を試みた。8をヘキサン溶液中で捕捉剤2,3-ジメチルブタジエン存在下で低圧水銀灯を用いて光照射すると、期待される捕捉生成物9が得られた。上述のようにo-キノンおよび1,3-ジエン付加体6および9が生成することはゲルマシクロペンタジエニリデン類1および2がシラシクロペンタジエニリデン類と同様に4π反芳香族的な性質を有することを示唆している。, 11120216
1999 - 1999 - 環状共役シリレン類の合成と二量化
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 特定領域研究(A), 最近、新規な環状シリレン、シラシクロペンタジエニリデン1を生成させ、その反応性が単純シリレンと同様、その電子系は反芳香族4p電子系であることを示した。今回、芳香族性が期待される環内p-電子が2個多いシラシクロヘプタトリエニリデン2を発生させ、その構造等を非経験的分子軌道計算を用いて検討した。 計算結果は1に比較して二重結合と単結合間の結合交替の度合いが小さいく環内炭素上のp-電子は2配位ケイ素電子上の空p軌道を通した相互作用、すなわち非局在化を示唆している。また、7員環の内角の和は899.2°とほぼ平面に近い。このような分子構造は2が芳香族性を有するとして合理的に理解できる。2の母体化合物1,1-ジメチル-1-シラシクロヘプタ-2,4,6-トリエン(シレピン)ではケイ素原子を通したp電子系の相互作用はなく、安定コンホーメションは舟形である。つぎに、2の前駆体を2,3-ジメチルブタジエンおよびヒドロシランを存在下光分解し、2を発生させた。その結果、対応する環化付加物および挿入生成物がそれぞれ良好な収率で得られた。このことは2で2配位ケイ素原子上の電子対がn-軌道を占めるという上記の電子配置と一致する。次いで前駆体を3-メチルペンタン中、77Kでマトリックス中で光照射したところ、2に由来するUVスペクトル(極大:610nm,450nmおよび474nm)が観測された。, 10133215
1997 - 1998 - 新規ヘテロクラスタ-の合成に関する研究
加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 奨励研究(A), 1、 一次元オリゴシランの逐次合成に対し、ケイ素鎖伸長試剤として リチウム化合物とマグネシウム化合物を併用することにより各種の任意の鎖長を有する一次元オリゴシランを得ることができた。また分岐状オリゴシランも同様の手法で合成された。 2、 またオリゴシラン類の化学的特性にも興味が持たれておりその電子的供与性を検討した。種々のオリゴシラン類とケトン類の光反応を検討したところシリレン授受反応やケイ素ケイ素結合間へのカルボニル挿入反応が起こることを見いだした。この反応は励起カルボニル種とオリゴシランとの電子移動反応によって進行することをレーザーフラッシュフォトシスによって明らかにした。同反応を四塩化炭素存在下で行うとクロロシラン類が得られてくることより中間体としてシリルラジカルが生成していることが示唆される。また反応の溶媒効果を検討し極性溶媒中では電子移動反応が速やかに進むが低極性溶媒中では遅く励起錯体を経由すると考えられる。また使用するケトンの種類によって生成物の選択性が制御される興味深い結果も得られた。 3、 オリゴシランの基本的性質を調べるためケイ素ーケイ素結合の置換した不飽和化合物の光反応を検討した。こららの反応では分子内シリル基の転位により数段階の異性化を起こすことが知られているが反応メカニズムについては不明の点が多い。ビニルジシランの光反応においてジシラシクロプロパン中間体の生成を初めて確認した。またジシラシクロヘキサジエンの電子移動反応を初めて検討し環縮少が起こりシロールが生成することを確認した。, 09740465
1997 - 1998 - 環状共役シリレン類の合成と二量化
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 重点領域研究, シラシクロペンタジエン(シロール)の化学は大いに進展し新しい世紀をむかえた。ここでは対応する新規な2配位ケイ素化学種、シラシクロペンタジエニリデンの合成と反応性、さらに理論的立場からもその構造および電子状態に検討を加えた。 スピロビスシロールをシクロオクチンとベンゼン中反応させるとシリレン前駆体が対応する付加体として得られる。この前駆体は有効なシリレン捕捉剤であるEtMe_2SiHあるいは2,3-ジメチルブタジエン存在下で光分解すると、速やかに反応する挿入生成物および付加環化生成物を脱離生成物とともに与える。この前駆体を3-メチルペンタン(3-MP)マトリックス中77Kで光分解すると、ca.500nmに弱い吸収帯が出現し、吸収強度は照射とともに増加する。また、吸収帯はマトリックスを融解させると完全に消失する。マトリックス中にEtMe_2SiHあるいは2,3-ジメチルブタジエンを存在させると、対応する挿入生成物および付加環化生成物が生成する。以上の実験事実はテトラフェニルシラシクロペンタジエニリデンがマトリックス中で生成したことを示している。電子状態の知見を得るため、無置換シラシクロペンタジエニリデンのabinitio計算を行った。基底一重項および三重項の最適化構造はともにC_<2V>対称で、一重項が三重項より13.1kcal/mol安定であると計算され、環内のブタジエン部分のC-C結合の間には大きな結合交替が観測される。したがって、その反応性を考慮するとsp^2骨格からなるシラシクロペンタジエニリデンではケイ素上の孤立電子対は平面内にあって、反芳香族4π電子系であると帰属される。, 09239215
1997 - 1997 - 14族元素環状共役化合物および関連化合物の合成と反応
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 重点領域研究, 有機ゲルマニウム-ゲルマニウム(Ge-Ge)結合の基本的な化学を研究する目的で環歪みで活性化されたGe-Ge結合をもつ3,4-ベンゾ-1,1,2,2-テトラエチル-1,2-ジゲルマシクロブト-3-エン(1)を合成し、その物性および反応性等を検討した。 1は1,2-ビス(ジエチルゲルミル)ベンゼンを四塩化炭素で塩素化して得られる1,2-ビス(クロロジエチルゲルミル)ベンゼンをトルエン中、金属ナトリウムと反応させて合成した。1は極めて反応性に富み、徐々に酸化されてジゲルモキサン結合を持つ2を与えた。また、単体イオウとも反応し、Ge-Ge結合にイオウが挿入した3を生成した。1をトルエン溶液として脱気封管中、室温から60℃程度で反応させると、トルエンやTHF等に可溶な数平均分子量が数十万程度の開環重合体を生成した。次に、1を脱気封管中、160℃で加熱すると4,5-ベンゾ-1,1,2,2,3,3-ヘキサエチル-1,2,3-トリゲルマシクロペント-4-エン(5)および3,4,6,7-ジベンゾ-1,1,2,2,5,5-ヘキサエチル-1,2,5-トリゲルマシクロヘプト-3,6-ジエン(6)が生成した。一方、パラジウム0価錯体を触媒として、フェニルアセチレンを反応させると、室温で5,6-ベンゾ-2-フェニル-1,1,4,4-テトラエチル-1,4-ジゲルマシクロヘキサ-2,5-ジエン(9)が高収率で生成した。他方、1にパラジウム触媒を加えて、反応させると、Ge-Ge結合でメタセシス反応が進行して二量体14が高収率で生成した。さらに、1を脱気封管中、パラジウム触媒と共にさらに高温に加熱すると14とは異なる二量体15がその異性体16および17と共に生成した。これらは中間にゲルミレン錯体18を経由して生成したとして理解できる。, 07216227
1995 - 1995 - 低配位型高周期14族元素活性種の合成と安定化
加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 奨励研究(A), 本研究ではかさ高い保護基として、トリシル(トリストリメチルシリルメチル;(Me_3Si)_3C-)系置換基の原料となる化合物の合成を試みた。まずハロゲン化炭化水素とハロシランとを用いて還元的にカップリングさせる方法を試みたが、イソプロピル基やtert-ブチル基の入ったトリシル誘導体をほとんど得ることができなかった。次にトリシル骨格を形成した上で結合手の先端をハロゲン化して、アルキル基をリチウム試薬で導入する方法による合成を試みた。有機金属試薬とハロシラン類との反応性は、かさ高さなどケイ素上の立体環境と脱離基の種類に依存するため、Br、Cl、F体各ハロシラン類と様々なアルキルリチウムの組み合せを検討した。その結果(^iPrMe_2Si)_3CHと((Me_3SiCH_2)Me_2Si)_3CHの2つの化合物を合成することができた。中心炭素をMeLi等でリチオ化することにより、新規な保護基として活用できるものと思われる。 またこれに関連して電子移動反応条件下での低配位型活性種発生の観点から立体保護基を有するケイ素架橋芳香族化合物の光誘起電子移動反応を検討した。シラノルボルナジエンにおいては予想した二価活性種シリレンの生成を示唆する結果を得た。またケイ素基の段階的転移によって二種の異性体を生成することがわかった。酸素による捕捉実験により、開環型中間体の関与が示唆された。またその構造をX線結晶構造解析によって明らかにした。求核剤を存在させて反応をおこなうと、脱離した架橋部分の捕捉生成物が得られた。これは生成したカチオンラジカルのSi-C結合が段階的に、求核剤により開裂されて捕捉されたと説明される。 立体保護基を有するジシラビシクロオクタジエンの場合も同様にカチオンラジカルSi-C結合が開裂される開裂を受ける。さらにジシレン架橋部脱離に至る中間体の二量化生成物の単離に成功した。これは単量体のラジカルが、ケイ素上の立体保護基により安定化されかなり長寿命であることを示していおり従来不明であったSi-C結合の開裂が段階的に進行することを証明している。, 06854031
1994 - 1994 - 真空紫外光による単純な有機14族化合物の光分解
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 重点領域研究, ペルメチルポリシランの光分解過程は溶液中の研究で一般的な開裂様式が明らかにされている。しかし、より基本なアルキルシラン類に関しては1、2の気相光分解の報告のみである。本研究では数種の単純なペルアルキルシラン類の真空紫外光分解を、ポリシラン類と同様にシクロヘキサン溶液中で行い、溶液反応での特徴およびケイ素鎖長の効果を検討した。 テトラブチルシラン1では、トリブチルシラン4が微量のオクタンとともに生成し、ヒドロシラン存在下では、シリレン挿入生成物5が得られる。ヘキサメチルジシラン2ではトリメチルシラン6、テトラメチルシラン7および1,3-ジシラシクロブタン8が生成し、ヒドロシラン存在下ではシリレン挿入生成物10が得られる。以上から、アルキルシランおよびジシラン類の光分解の主経路はホモリシスによるシリルラジカルの生成であり、低効率ではあるがシリレン脱離が競争的に進行している。一方、オクタメチルトリシラン3では6、2および8が生成し、ヒドロシラン存在下ではシリレン捕捉生成物10が得られる。トリシラン3では1および2と異なり、シリレン脱離が主過程となり、ホモリシスがこれと競争的に起こっている。 アルキルシランおよびジシランの溶液相光分解は気相と形式的には同じ機構で進行している。今回溶液反応によりシリレン脱離過程の存在が初めて確立した。しかし、ジシランについては気相で波長依存性も示唆され、反応活性種の動的挙動等さらに詳細な検討が必要である。溶液中では中間活性種間の反応が不均化に限られ気相に比して生成物はより単純である。, 06239222
1994 - 1994 - 14族元素環状化合物および関連化合物の合成と反応
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 重点領域研究, テトラシラシクロオクタジイン3は環状σ-π相互作用のために特異な電子的性質を示す。本研究ではこの種の相互作用および反応性に対する元素効果を、ケイ素原子をゲルマニウム原子に置換した新規なゲルマニウム類縁体3,3,4,4,7,7,8,8-オクタメチル-3,4,7,8,-テトラゲルマ-1,5,-ジイン(1)および3,3,4,4,7,7,8,8-オクタメチル-3,4,-ジシラ-7,8-ジゲルマ-1,5-ジイン(2)を合成して検討した。 1、2および3はたがいに極めて類似した光電子スペクトル(PE)を示し、1および2でも3と同型のアセチレンπ軌道と金属-金属σ軌道間の環状σ-π相互作用が有効である。1および3のイオン化ポテンシャル(IP)を考慮すると、第四周期元素であるゲルマニウム-ゲルマニウム(Ge-Ge)σ軌道と炭素-炭素(C-C)π軌道との相互作用が第三周期元素であるケイ素-ケイ素(Si-Si)σ軌道とC-Cπ軌道間の相互作用と同程度有効であることがわかる。しかし、UVスペクトルではSi-Si結合をGe-Ge結合に置換するとその吸収極大波長は短波長にシフトする。このことはゲルマニウム類縁体1および2では対応するケイ素化合物3に比べてLUMOが上昇していることを示唆する。 1、2および3は塩化メチレン中テトラシアノエチレン(TCNE)とCT錯体を形成してCT吸収を示す。1は塩化メチレン中TCNE存在下でオリゴメル化し、1.5量体および二量体を与える。一方、より極性なアセトニトリル中ではポリメリ化して、対応するポリマーを与える。この極性溶媒では2も対応するポリマーに定量的に変換されるが、Si-Si結合のみでGe-Ge結合を持たない3はCT錯体は形成するがポリメリ化はしない。, 06227226
1994 - 1994 - 高周期14族元素を骨格に含む芳香族化合物の開発研究
加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 奨励研究(A), シラシクロペンタジエン(シロール)は環内にケイ素原子を含む最も基本的な共役環状化合物の一つであるが環内炭素上に置換基を持たないシラシクロペンタジエンはこれまで安定な単量体としては単離されていない。本研究では最初の安定な環内炭素無置換シラシクロペンタジエンとして1、1-ジメシチル-1-シラシクロペンタジエンを合成した。この化合物は熱的に安定であるがジエノフィルや遷移金属錯体と容易に反応することがわかった。 シクロペンタジエニリデンのケイ素類似体であるシラシクロペンタジエニリデンは環内二重結合とシリレン部位との相互作用に興味のもたれる化学種であるがこれまで報告例がない。シラシクロペンタジエニリデンの前駆体となりうる1、1-ビス(トリメチルシリル)-1-シラシクロペンタジエンを同様の方法論によって合成した。この化合物を光分解したところシラシクロペンタジエニリデンの発生を示唆するヘキサメチルジシランの生成が確認された。シリレンの良好な捕捉剤であるアルコール類、ジエン類、ヒドロシラン類の存在下における光分解反応ではシラシクロペンタジエニリデン由来の生成物は得られなかった。シラシクロペンタジエニリデンの発生を確認するための反応条件及び前駆体の改良を検討する予定である。 シラシクロペンタジエンのラジカルイオン種の発生を目的としてその電子移動反応を検討した。1、1-ジメシチル-1-シラシクロペンタジエンは電子受容体であるテトラシアノエチレンとの間で電荷移動錯体を形成した。その電荷移動吸収帯に光照射するとケイ素-炭素結合の開裂が起こった。四塩化炭素共存下では塩素引き抜きがみられたことから電子移動によりシラシクロペンタジエンラジカルカチオンが生成しているものと考えられる。, 05854049
1993 - 1994 - 光誘起電子移動による有機ケイ素反応活性種の発生と新規シロール誘導体の設計と合成
中平 靖弘; 加固 昌寛
日本学術振興会, 科学研究費助成事業, 電気通信大学, 重点領域研究, 光誘起電子移動反応条件でケイ素架橋化合物が反応活性種特にカチオンラジカル種を発生する可能性を検討した。この過程でケイ素-ケイ素結合の新しい光フッ素化開裂反応を見いだした。 1.ケイ素架橋多環式化合物の異性化と反応活性種の捕捉 9,10-ジシアノアントラセン存在下タングステン(W)ランプの照射で、ジベンゾシラノルボルナジエン誘導体(1)は骨格転位して2-シラ-3,4,6,7-ジベンゾビシクロ〔3.2.0〕ヘプタジエン異性体3をアントラセンと共に生成した。1およびジシラビシクロ〔2.2.2〕オクタジエン誘導体(2)は2,4,6-トリフェニルピリリウムテトラフルオロボラート(TPP^+BF_4^-)存在下のW-ランプ照射で形式的にケイ素架橋部に対応する反応活性ケイ素種がフッ素に捕捉されたジフルオロシランを与えた。 2.光フッ素化開裂反応 フェニルジシラン類およびオクタメチルトリシランはTPP^+BF_4^-存在下W-ランプを照射するとケイ素-ケイ素結合がフッ素化開裂を受け対応するフルオロシランを与えた。たとえば、1,2-ジフェニルテトラメチルジシランからはフルオロメチルジフェニルシランが定量的に得られる。この光フッ素化開裂はシクロヘキサシラン等の環状オリゴシランでも進行した。 3.シロール類の設計と合成 ジエン部分に置換基を持たないビストリメチルシリルシロールをはじめて合成した。, 05236215
1993 - 1993 - Basic Studies on Photo- and Thermal-Reactions of 14 Group Metal Compounds
NAKADAIRA Yasuhiro; KAKO Masahiro
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, University of Electro-Communications, Grant-in-Aid for General Scientific Research (C), 1.185 nm photolysis of octamethyltrisilane, hexamethyldisilane, and tetrabutylsilane In the trisilane, elimination of dimethylsilylene competes favorably with homolysis of Si-Si bonds. In the disilane, homolysis of the Si-Si bond prevails over silylene generation, which is confirmed by detection of tetramethylsilane and the trapping experiment. In the monosilane, cleavage of Si-C bonds predominates but a trac7e of dibutylsilylene is detected by the trapping experiment. 2.185 nm photolysis of hexamethyldigermane Photochemical behavior of the digermane has been shown t'o be qu ite similar to those of the 'corresponding silicon analog, but the elimination of the divalent species is much more effective in the germanium analog. 3. Photolysis of aryl-substituted 14 group metal catenates, PhMe_2E-E'Me_3 (E, E' = Si, Ge) Photolysis of PhMe_2SiGeMe_3, PhMe_2GeSiMe_3, and PhMe_2GeGeMe_3 have been examined. Their photochemical behavior can be rationalized by the radical pair generated by homolysis of the E-E' bond. 4. Analogy between photo-induced electron transfer reaction and the mass spectral fragmentation Mass spectra of polysilaalkanols are rationalized based on their chemical reactivities under photo-induced electron transfer conditions. 5. Photo-induced transfer reaction of trifluoromethyl-substituted benzenes with hexamethyldisilane and octamethyltrisilane Under these conditions, substitution of the fluorine with the silyl function, and silylation of the aromatic ring have shown to take place., 02640387
1990 - 1991