Synthesis and Characterization of a Gold Vinylidene Complex Lacking -Conjugated Heteroatoms

Hydride abstraction from the gold (disilyl)ethylacetylide complex [(P)Au{n(1)-C equivalent to CSi(Me)(2)CH2CH2SiMe2H}] (P=P(tBu)(2)o-biphenyl) with triphenylcarbenium tetrakis(pentafluorophenyl)borate at -20 degrees C formed the cationic gold (ss,ss-disilyl)vinylidene complex [(P)Au=C=CSi(Me)(2)CH2CH2Si(Me)(2)]B+(C6F5)(4)(-) with >= 90% selectivity. Si-29 NMR analysis of this complex pointed to delocalization of positive charge onto both the ss-silyl groups and the (P)Au fragment. The C1 and C2 carbon atoms of the vinylidene complex underwent facile interconversion (Delta G(#)=9.7 kcalmol(-1)), presumably via the gold pi-disilacyclohexyne intermediate [(P)Au{eta(2)-C equivalent to CSi(Me)(2)CH2CH2Si(Me)(2)}]B+(C6F5)(4)(-).