Aurolysis of α-C-deprotonated group 6 aminocarbene and thiocarbene complexes with Ph3PAu+

Abstract

Deprotonated Fischer-type aminocarbene complexes, (CO)₅MC(NR₂)CH₃ (M = Cr or W; R = Me or propyl), react with Ph₃PAu⁺ by metal group substitution – (CO)₅M for Ph₃PAu⁺ – and attachment of the extricated M(CO)₅ to the deprotonated methyl group. (The products may also be seen as aminovinylgold compounds coordinated to M(CO)₅ moieties.) DFT calculations at the B3LYP level of theory using model compounds indicate a clear preference of the gold unit for central C to terminal coordination in the ligand [NMe₂CCH₂]⁻, whereas the Cr(CO)₅ has a 7 kcal mol⁻¹ preference for C(vinyl) coordination compared to N-coordination. In related thiocarbenes, the sulfur donor atom should be the preferred point of attachment for the metal carbonyl unit. The latter prediction is borne out in practice, and in the three products isolated, including Ph₃PAu{C(CH₂)SPh}Cr(CO)₅ in a mixed crystal with [Ph₃PAuSPh]Cr(CO)₅, precisely this coordination mode is present. The latter component of the mixed crystal has also been prepared independently of the vinyl one.