The Scope of Ambiphilic Acetate‐Assisted Cyclometallation with Half‐Sandwich Complexes of Iridium, Rhodium and Ruthenium

CH activation by acetate-assisted cyclometallation of a phenyl group with half-sandwich complexes [{MCl2Cp*}2] (M=Ir, Rh) and [{RuCl2(p-cymene)}2] can be directed by a wide range of nitrogen donor ligands including pyrazole, oxazoline, oxime, imidazole and triazole, and X-ray structures of a number of complexes are reported. All the ligands tested cyclometallated at iridium, however ruthenium and rhodium fail to cause cyclometallation in some cases. As a result, the nitrogen donors have been categorised based on their reactivity with the three metals used. The relevance of these cyclometallation reactions to catalytic synthesis of carbocycles and heterocycles is discussed.