The Stabilizing Effects in Gold Carbene Complexes

Bonding and stabilizing effects in gold carbene complexes are investigated by using Kohn–Sham density functional theory (DFT) and the intrinsic bond orbital (IBO) approach. The π‐stabilizing effects of organic substituents at the carbene carbon atom coordinated to the gold atom are evaluated for a series of recently isolated and characterized complexes, as well as intermediates of prototypical 1,6‐enyne cyclization reactions. The results indicate that these effects are of particular importance for gold complexes especially because of the low π‐backbonding contribution from the gold atom. Is anybody there? Intrinsic bond orbital analyses based on DFT calculations on gold carbene complexes indicate little π backbonding from gold (A) and π stabilization from organic fragments even in cyclopropyl‐substituted gold carbene complex intermediates (B, C).