Iridium Carbene and Carbamoyl Complexes Supported by a Tetradentate Pyridine‐Carboxamide Ligand

The nucleophilic attack of an Ir III isocyanide complex bearing a tetradentate pyridine‐carboxamide ligand with amines to give carbene and carbamoyl complexes has been studied. The treatment of Na[Ir(bpb)Cl 2 ] {bpb 2– = dianion of 1,2‐bis(2‐pyridinecarboxamido)benzene} with PR 3 (R = p ‐tolyl) in refluxing glycol gave [Ir(bpb)(PR 3 )Cl] ( 1 ). Chloride abstraction of 1 with silver tosylate (AgOTs) led to isolation of a mixture of [Ir(bpb)(PR 3 )(OTs)] ( 2a ) and [Ir(bpb)(PR 3 )(H 2 O)](OTs) ( 2b ) that reacted with 2,6‐dimethylphenyl isocyanide (CNxyl) and 4‐ tert ‐butylaniline to give [Ir(bpb)(PR 3 )(CNxyl)](OTs) ( 3 ) and [Ir(bpb)(PR 3 )(4‐ t BuC 6 H 4 NH 2 )](OTs) ( 4 ), respectively. The reaction of 4 with AgOTf (OTf – = triflate) yielded an Ir–Ag dimeric complex, [Ir(bpb)(PR 3 )(4‐ t BuC 6 H 4 NH 2 ){Ag(H 2 O)(µ‐OTf)}] 2 (OTf) 2 ( 5 ). Whereas nucleophilic attack of 3 with benzylamine (BnNH 2 ) afforded the carbene complex [Ir(bpb)(PR 3 ){C(NHBn)(NHxyl)}](OTs) ( 6 ), that with t BuNH 2 yielded the carbamoyl complex [Ir(bpb)(PR 3 ){C(O)NHxyl}] ( 7 ). The Ir IV –Ir III redox potentials for Ir(bpb) complexes have been determined using cyclic voltammetry. The crystal structures of 2a , 2b , and 5 – 7 have been determined.