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

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-kappa(2)/N,N')]PF6 center dot CHCl3 (1) and [Ir(H)(2)(PPh3)(2)(terpy-kappa N-2,N')]BF4 center dot Me2CO (2) with two cis hydride atoms, two PPh3 and terpy-kappa N-2,N' possess a octahedral N2P2H2 coordination mode, while pincerlike Ir(III)-terpy hydride complex {[Ir(H)(PPh3)(2)(terpy-kappa(3)/N,N',N '')](BF4)(2)center dot 2CH(2)Cl(2)}(2) (3) with one hydride atom, two PPh3 and terpy-kappa N-3,N',N '' possess a octahedral N3P2H coordination mode. H-1 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 H-1 NMR upfield shifts could be induced by the ring current effect from the phenyl groups of adjacent PPh3 ligands.