Technetium-Carbon Multiple Bonds: Synthesis and Structure of Tc(:C:CHPh)Cl(dppe)2 and [Tc(.tplbond.CCH2-t-Bu)Cl(dppe)2

Abstract

The 16-electron complex TcCl(dppe)[sub 2] reacts with terminal alkynes to form neutral vinylidene complexes of the type Tc(=C=CHR)Cl(dppe)[sub 2] (R = Ph, Me, t-Bu). Treatment of these vinylidene complexes with acid (HBF[sub 4] for R = Ph, HNMe[sub 3]BPh[sub 4] for R = t-Bu) yields the respective terminal carbyne complexes Tc([triple bond]CCH[sub 2]R)-Cl(dppe)[sub 2][sup +] (R = Ph, t-Bu). These vinylidene and carbyne compounds represent the first examples of technetium carbenes or carbynes. X-ray structures of Tc(=C=CHPh)Cl(ddpe)[sub 2] and Tc([triple bond]CCH[sub 2]-t-Bu)Cl(dppe)[sub 2[minus]+] were determined, and the Tc-C bond lengths obtained were 1.861(9) and 1.724(7) A, respectively. 13 refs., 2 figs.