The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C
4Ph
4SiMe)
2] (
1) with either Li or Na in THF gives the silole anion [MeSiC
4Ph
4]
− (
2). The head-to-tail dimerization of
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The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C
4Ph
4SiMe)
2] (
1) with either Li or Na in THF gives the silole anion [MeSiC
4Ph
4]
− (
2). The head-to-tail dimerization of the silole anion
2 gives crystals of the disilatricyclic diallylic dianion [(C
4Ph
4SiMe)
2]
−2 (
3). The derivatization of
3 (crystals) with bromoethane (gas) under reduced pressure provides [(MeSiC
4Ph
4Et)
2] (
4) quantitatively. The reverse addition of
3 in THF to trimethylsilyl chloride, hydrogen chloride, and bromoethane in THF gives 1-methyl-1-trimethylsilyl-1-silole [Me
3SiMeSiC
4Ph
4] (
6), 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C
4Ph
4H
2SiMe-MeSiC
4Ph
4] (
7), and 1-methyl-2,5-diethyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C
4Ph
4Et
2SiMe-MeSiC
4Ph
4] (
8), respectively. The reaction products unambiguously suggest that the silole anion [MeSiC
4Ph
4]
− is generated by coordination of the chloride ion at the silicon atom in
3 or by the nucleophilic substitution of either chloride or bromide ion at one of two silicon atoms in
3. The quenching reaction of
3 dissolved in THF with water gives 1,2,3,4-tetraphenyl-2-butene, the disiloxane of 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl [O(MeSiC
4Ph
4)
2] (
10) and methyl silicate.
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