Reactivity of the Disilyne RSiSiR (R = SiiPr[CH(SiMe3)2]2) toward Nitriles: Unexpected Formation of Triaza-1,4-disilabicyclo[2.2.2]octa-2,5,7-triene Derivatives

The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)-methyl]-1,4-diisopropyl-2-tetrasilyne (1) with acetonitrile or benzonitrile produced the tris adduct triaza-1,4-disilabicyclo[2.2.2]octa-2,5,7-triene derivatives RSi(N=CR')(3)SiR (R = (SiPr)-Pr-i[CH(SiMe3)(2)](2), R' = Me (2a), Ph (2b)), which were characterized by spectroscopic data as well as X-ray crystallography (for 2b). Theoretical calculations on the reaction between the disilyne and nitriles show that the reaction starts with the interaction between the LUMO (pi(in)*) of 1 and the HOMO (lone pair) of the nitriles, followed by several consecutive steps to produce the diazadisila-Dewar benzene intermediate, which reacts with the third nitrile molecule to produce the final products.