Syntheses and structural characterizations of mononuclear Ir(III) hydride complexes with 2,2′:6′,2″-terpyridine in the κ2N,N' and κ3N,N',N″ coordination modes

Abstract

The reactions of [Ir(H)2(PPh3)2(Me2CO)2]X (X = PF6, BF4) with terpy in CHCl3, Me2CO and CH2Cl2 under Ar afforded three novel Ir(III)-hydride complexes 1–3 by the choices of solvents and anions. Ir(III)-terpy hydride complexes [Ir(H)2(PPh3)2(terpy-κ2N,N')]PF6·CHCl3 (1) and [Ir(H)2(PPh3)2(terpy-κ2N,N')]BF4·Me2CO (2) with two cis hydride atoms, two PPh3 and terpy-κ2N,N' possess a octahedral N2P2H2 coordination mode, while pincer-like Ir(III)-terpy hydride complex {[Ir(H)(PPh3)2(terpy-κ3N,N',N″)](BF4)2·2CH2Cl2}2 (3) with one hydride atom, two PPh3 and terpy-κ3N,N',N″ possess a octahedral N3P2H coordination mode. 1H NMR analyses showed that the asymmetric and symmetric structures of three Ir(III)-terpy hydride complexes 1–3 are kept in solution. It was found that the significant 1H NMR upfield shifts could be induced by the ring current effect from the phenyl groups of adjacent PPh3 ligands.