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 η2 and η1 coordination mode occurs. A related zinc complex containing two [B=C]− ligands was prepared as a further point of comparison for the η1 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 d10 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. A series of neutral coinage‐metal boryl complexes featuring a side‐on [B=C]− containing ligand have been isolated and characterised. The compounds are isoelectronic with alkene complexes, which are crucial intermediates in catalysis. Both the strength of binding and the propensity for deviation toward η1 coordination are more favourable for Au over Ag and Cu.