TY - JOUR
T1 - Electronic structures and redox properties of silylmethylated C60
AU - Nagashima, Hideo
AU - Saito, Masayuki
AU - Kato, Yoshiyuki
AU - Goto, Hitoshi
AU - Osawa, Eiji
AU - Haga, Masaaki
AU - Itoh, Kenji
N1 - Funding Information:
calculations that the the products obtained by silylmethylation of C60 would be the \[6,6\]-isomeor f I and the \[1,4\]-isomeor f 2, of which optimized structures were proposed as shown in Figure 2. Second, calculated orbital energies predicted that silylmethylated fullerenes were worse electron acceptors and better electron donors than C60. These predictions were acturally proved by electrochemical methods. Semi-empirical MO calculations and electrochemical measurements, either one or both have taken part in understanding structures and electronic properties of fullerenes and their derivatives.l,2, 21 As related work, we should refer to publications by Hirsch, 8a Fagan and Evans, 22b and Kadish, 13 who reported AM1 calculations of C60(Me)H, electrochemical studies of C60(tBu)(Me), and electrochemical studies of C60(CH3)2, respectively. Electronic properties depicted for these compounds are essentially similar to our results on the silylmethylated C60. Thus, organosilyl groups in silylmethylated C60 themselves do not affect the electronic properties of the compounds. As described earlier, silylmethyl groups effectively contribute to linking the C60 moieties to various organic and inorganic groups. We have established synthetic methods of two types of silylmethylated fullerenes 1 or 2 by Grignard addition reactions. The silylmethyl magnesium reagents having alkyl, aryl, vinyl, or alkoxy groups on the silicon atom can be used for the reaction; this means that the CH2Me2Si moiety act as a bridge between these groups with the C60 cage. Replacement of the iprO groups in le or 2e by alcohols and phenols have provided a general way linking the C60 moieties to organic groups in alcohols and phenols through silicon-oxygen bonds. An interesting application of this replacement reaction is attachment of C60(H)CH2Me2Si group to surface of silica; this modified silica has proven to be useful as a unique stationary phase of micro-column HPLC, which can effectively separate fullerenes and or polyaromatic hydrocarbons. 14 From a view of synthetic planning of novel fullerene molecules, these processes offer a general way to introduce "fullerenomethylsilyl groups" to various organic or inorganic moieties. Theoretical and electrochemical studies presented in this paper contribute to understanding geometrical or electronic nature of the "fullerenomethylsilyl groups", so that chemists could have real images what will happen to connect any desired organic or inorganic materials to C60 moieties through CH2Me2Si or CH2Me2SiO groups. This work was supported by a grant from the Ministry of Education, Science, and Culture of the Japanese Government (0523105).
PY - 1996/4/1
Y1 - 1996/4/1
N2 - Theoretical and electrochemical studies were performed to understand the electronic structure and the redox property of two types of silylmethylated C60, C60(H)(CH2SiMe2Y) (1) and C60(CH2SiMe2Y)2 (2) [Y = alkyl, aryl, OR, F]. Semi-empirical molecular orbital (MO) calculations for 1a (Y = Me of 1) and 2a (Y = Me of 2), and their model compounds, C60(H)(Me) (3) and C60(Me)2 (4) revealed the thermodynamically most stable isomer of each compound. Cyclic voltammograms showed three to five reversible reduction waves and a quasi-reversible oxidation wave; the redox potentials are consistent with those expected from frontier orbital energies calculated by AM1.
AB - Theoretical and electrochemical studies were performed to understand the electronic structure and the redox property of two types of silylmethylated C60, C60(H)(CH2SiMe2Y) (1) and C60(CH2SiMe2Y)2 (2) [Y = alkyl, aryl, OR, F]. Semi-empirical molecular orbital (MO) calculations for 1a (Y = Me of 1) and 2a (Y = Me of 2), and their model compounds, C60(H)(Me) (3) and C60(Me)2 (4) revealed the thermodynamically most stable isomer of each compound. Cyclic voltammograms showed three to five reversible reduction waves and a quasi-reversible oxidation wave; the redox potentials are consistent with those expected from frontier orbital energies calculated by AM1.
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U2 - 10.1016/0040-4020(96)00113-5
DO - 10.1016/0040-4020(96)00113-5
M3 - Article
AN - SCOPUS:0029920313
VL - 52
SP - 5053
EP - 5064
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 14
ER -