Electrophilic addition of Ph₃PAu⁺ to anionic alkoxy Fischer-type carbene complexes: A novel approach to metal-stabilized bimetallic vinyl ether complexes

The addition of the Ph₃PAu⁺ electrophile to deprotonated Fischer-type alkoxy(methyl)-carbene complexes of pentacarbonyl group 6 metals leads to the formation of novel vinyl ether complexes of gold coordinated to the pentacarbonylmetal moiety. X-ray structures and DFT calculations show that the greatest bonding contribution in the vinyl coordination to the M(CO)₅ fragment comes from the terminal, partially negatively charged, CH₂ carbon atom via partial end-on η¹-bonding rather than the usual η²-bonding of olefins. The corresponding positive charge from the asymmetric vinyl coordination is mainly delocalized onto the Ph₃PAu fragment, stabilizing this coordination mode. The use of W instead of Cr in the M(CO)₅ fragment, in otherwise isostructural compounds, results in somewhat greater asymmetry in the vinyl coordination, with the difference in the two M(CO)₅-η²-vinyl carbon bond lengths increasing from 0.252(11) Å (M = Cr) to 0.307(5) Å (M = W) in the solid state.