Group 11 Borataalkene Complexes: Models for Alkene Activation.

A series of linear late transition metal (M=Cu, Ag, Au and Zn) complexes featuring a side-on [B=C] containing ligand have been isolated and characterised. The [B=C] moiety is isoelectronic with the C=C system of an alkene. Comparison across the series shows that in the solid-state, deviation between the η and η coordination mode occurs. A related zinc complex containing two [B=C] ligands was prepared as a further point of comparison for the η coordination mode. The bonding in these new complexes has been interrogated by computational techniques (QTAIM, NBO, ETS-NOCV) and rationalised in terms of the Dewar-Chatt-Duncanson model. The combined structural and computational data provide unique insight into catalytically relevant linear d complexes of Cu, Ag and Au. Slippage is proposed to play a key role in catalytic reactions of alkenes through disruption and polarisation of the π-system. Through the preparation and analysis of a consistent series of group 11 complexes, we show that variation of the metal can impact the coordination mode and hence substrate activation.