A New Disilene with π-Accepting Groups from the Reaction of Disilyne RSiSiR (R = SiiPr[CH(SiMe3)2]) with Isocyanides

The reaction of 1,1,4,4-tetrakis­[bis­(trimethylsilyl)­methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne–isocyanide adducts [RSiSiR­(CNR′)2] (R = SiiPr­[CH­(SiMe3)2]2, R′ = tBu (2a) or CMe2CH2tBu (2b)), which are stable below −30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R­(NC)­SiSi­(CN)­R (3) and 1,2-dicyanodisilane R­(NC)­HSiSiH­(CN)­R (4) via C–N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.