The first stable methyl-substituted disilene: Synthesis, crystal structure, and regiospecific MeLi addition

The reductive debromination of 3,3-dibromo-1, 1, 5,5- tetra-tert-butyl-2,4- bis(di-tert-butylmethylsilyl)-1,2,4,0-tetramethylpentasilane, [((t)Bu(2)MeSi)(2)MeSi](2)SiBr(2) (1), gave (E)-[((t)Bu(2)MeSi)(2)MeSi]((t)Bu(2)MeSi)Si=SiMe-(SiMe(t)Bu(2)) (3), which is the first methyl-substituted isolable disilene, and its structure was determined by X-ray crystallography. The regioselective addition of a methyl anion to the Si=Si bond in 3 took place to give the solvent-separated silyl anion species tetrakis(tetrahydrofuran)lithium(I) 1,1,5,5-tetra-tert-butyl-2,3-bis(di-tert-butylmethylsilyl)-1,2,4,4,5-pentamethylpentasilan- 3-ide (4).