Cationic, Two-Coordinate Gold π Complexes

Cationic, two-coordinate gold complexes that contain a phosphine or N-heterocyclic supporting ligand have attracted considerable attention recently owing to the potential relevance of these species as intermediates in the gold-catalyzed functionalization of CC multiple bonds. Although neutral two-coordinate gold complexes have been known for over 40years, examples of the cationic two-coordinate gold(I) complexes germane to catalysis remained undocumented prior to 2006. This situation has changed dramatically in recent years and well-defined examples of two-coordinate, cationic gold complexes containing alkene, alkyne, diene, allene, and enol ether ligands have been documented. This Minireview highlights this recent work with a focus on the structure, bonding, and ligand exchange behavior of these complexes.