Isocyanide and carbene complexes of gold(I). The stepwise formation of formamidines

Abstract

The syntheses of Au(CNR¹)Cl and [Au(CNR¹)₂]PF₆(R¹= Bu^t or Prⁱ) from HAuCl₄, 4H₂O and [Buⁿ₄N][AuCl₄], respectively, and CNR₁ in ethanol are described. These complexes react with primary and secondary amines giving Au{C(NHR¹)(NHR²)}(NH₂R²)Cl,[Au{C(NHR¹)(NHR²)}₂]PF₆ and [Au{C(NHR¹)(NR₂³)}₂]PF₆(R¹= Bu^t R²= Bu^t, Prⁱ or Buⁿ; R¹= Prⁱ, R²= Bu^t or Prⁱ; R¹= Bu^t, R³= Et or CH₂Ph; R¹= Prⁱ, R³= Et). Treatment of [Au{C(NHBu^t)[N(CH₂Ph)₂]}₂]PF₆ with PPh₃ afforded [Au(PPh₃)₄]PF₆ and the formamidine CH(NBu^t)[N(CH₂Ph)₂], and of [Au{C(NHBu^t)₂}₂]PF₆ with CNBu^t, [Au(CNBu^t)₂]PF₆ and evidence for CH(NBu^t)-(NHBu^t).