title: Dissociation of the disilatricyclic diallylic dianion [(C4Ph4SiMe)2]-2 to the silole anion [MeSiC4Ph4]- by halide ion coordination or halide ion nucleophilic substitution at the silicon atom.
abstract: The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C(4)Ph(4)SiMe)(2)] (1) with either Li or Na in THF gives the silole anion [MeSiC(4)Ph(4)]- (2). The head-to-tail dimerization of the silole anion 2 gives crystals of the disilatricyclic diallylic dianion [(C(4)Ph(4)SiMe)(2)]-2 (3). The derivatization of 3 (crystals) with bromoethane (gas) under reduced pressure provides [(MeSiC(4)Ph(4)Et)(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(3)SiMeSiC(4)Ph(4)] (6), 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C(4)Ph(4)H(2)SiMe-MeSiC(4)Ph(4)] (7), and 1-methyl-2,5-diethyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C(4)Ph(4)Et(2)SiMe-MeSiC(4)Ph(4)] (8), respectively. The reaction products unambiguously suggest that the silole anion [MeSiC(4)Ph(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(4)Ph(4))(2)] (10) and methyl silicate.
authors: Department of Nanopolymer Material Engineering, Pai Chai University, 155-40 Baejae-ro (Doma-Dong), Seo-Gu, Daejon, 302-735, South Korea. jhong@pcu.ac.kr
authors: Jang-Hwan
authors: JH
authors: Hong
mesh_terms: D000838:Anions / Q000737:chemistry; D001965:Bromides / Q000737:chemistry; D002073:Butanes / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry; D018360:Crystallography, X-Ray; D003517:Cyclopentanes / Q000737:chemistry*; D019281:Dimerization; D008094:Lithium / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry
chemical_list: C570675:1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene); C570674:1,2,3,4-tetraphenyl-2-butene; D000838:Anions; D001965:Bromides; D002073:Butanes; D002712:Chlorides; D003517:Cyclopentanes; D012821:Silanes; D012828:Silicones; C540376:silole; C059468:disiloxane; D008094:Lithium; D012964:Sodium