Synthesis, Characterization, and Reactivity of Cationic Gold Diarylallenylidene Complexes

Methoxide abstraction from gold acetylide complexes of the form (L)Au[η¹ -C≡CC(OMe)ArAr'] (L=IPr, P(^t Bu)₂ (ortho-biphenyl); Ar/Ar'=C₆ H₄ X where X=H, Cl, Me, OMe) with trimethylsilyl trifluoromethanesulfonate (TMSOTf) at -78 °C resulted in the formation of the corresponding cationic gold diarylallenylidene complexes [(L)Au=C=C=CArAr']⁺  OTf^- in ≥85±5 % yield according to ¹ H NMR analysis. ¹³ C NMR and IR spectroscopic analysis of these complexes established the arene-dependent delocalization of positive charge on both the C1 and C3 allenylidene carbon atoms. The diphenylallenylidene complex [(IPr)Au=C=C=CPh₂ ]⁺  OTf^- reacted with heteroatom nucleophiles at the allenylidene C1 and/or C3 carbon atom.