Cyclometalated [Cp*M(C∧X)] (M = Ir, Rh; X = N, C, O, P) complexes

Half-sandwich Cp*Ir and Cp*Rh metalacycles have been successfully applied in traditional domains encompassing organic transformations and catalysis in recent years, especially the catalytic activation of C-H bonds. Cyclometalation has proven to be a highly attractive and versatile synthetic method for the formation of organometallic metalacycles. This review intends to describe isolated and well-defined cyclometalated iridium/rhodium complexes that contain a Cp*M-C (M = Ir, Rh) bond stabilised by the intramolecular coordination of neutral donor atoms (N, C, O or P). The formation of metalamacrocycles and cages employing cyclometalated approaches is discussed. In focusing on selected mechanistic insights garnered from iridium/ rhodium-catalysed functionalisation of C-H bonds involving cyclometalated complexes, a limited number of substrates will be discussed, but a broad range of mechanistic features is highlighted.