A New Disilene with π-Accepting Groups from the Reaction of Disilyne RSiSiR (R = Si^<i>i</i>Pr[CH(SiMe₃)₂]) with Isocyanides

The reaction of 1,1,4,4-tetrakis­[bis­(trimethylsilyl)­methyl]-1,4-diisopropyltetrasila-2-yne (<b>1</b>) with <i>tert</i>-butylisocyanide or <i>tert</i>-octylisocyanide produced the corresponding disilyne–isocyanide adducts [RSiSiR­(CNR′)₂] (R = Si^<i>i</i>Pr­[CH­(SiMe₃)₂]₂, R′ = ^<i>t</i>Bu (<b>2a</b>) or CMe₂CH₂^<i>t</i>Bu (<b>2b</b>)), which are stable below −30 °C and were characterized by spectroscopic data and, in the case of <b>2a</b>, X-ray crystallography. Upon warming to room temperature, <b>2</b> underwent thermal decomposition to produce 1,2-dicyanodisilene R­(NC)­SiSi­(CN)­R (<b>3</b>) and 1,2-dicyanodisilane R­(NC)­HSiSiH­(CN)­R (<b>4</b>) via C–N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative <b>3</b> was characterized by X-ray crystallography