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 eta(1)-bonding rather than the usual eta(2)-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)-eta(2)-vinyl carbon bond lengths increasing from 0.252(11) Angstrom (M = Cr) to 0.307(5) Angstrom (M = W) in the solid state.