The gold(iii)–CO bond: a missing piece in the gold carbonyl complex landscape

Abstract

We investigate the Au(III)–CO bond in the [(C^∧N^∧C)Au(III)CO]⁺ complex via charge-displacement (CD) analysis, revealing surprising peculiarities with respect to the Au(I)–CO bond. It shows a large Au(III) ← CO σ donation and, unexpectedly, an even larger Au(III) → CO π back-donation. The overall bonding picture, including a marked anisotropy in the Au(III) → CO in-plane and out-of-plane π back-donation components, is consistent with a CO carbon atom highly susceptible to nucleophilic attack.