Coordination behaviour of (diaryl disulfide)-bridged dinuclear thiairidaindan cores: ligand substitution by isocyanides, CO, hydrazines and hydroxylamine, and related reactions

Abstract

The diaryl disulfide ligand in the thiolato-bridged diiridium(III) complexes [{Ir(μ-SC₆H_{4 − n}Me_nCH₂)Cl(PPh₃)}₂(μ-ArSSAr)] [1a, n = 1, Ar = C₆H₃Me₂-2,6 (Xy); 1b, n = 2, Ar = C₆H₂Me₃-2,4,6 (Mes)] is readily substituted by isocyanides, CO, hydroxylamine and hydrazines to afford the bis(isocyanide), bis(carbonyl) and bis(hydroxylamine) complexes [Ir(μ-SC₆H_{4 − n}Me_nCH₂)Cl(PPh₃)(L)]₂ (2a, n = 1, L = XyNC; 2b, n = 2, L = XyNC; 3a, n = 1, L = Bu^tNC; 3b, n = 2, L = Bu^tNC; 4a, n = 1, L = CO; 4b, n = 2, L = CO; 7a, n = 1, L = NH₂OH; 7b, n = 2, L = NH₂OH) and the bridging hydrazine complexes [{Ir(μ-SC₆H_{4 − n}Me_nCH₂)Cl(PPh₃)}₂(μ-NH₂NR₂)] (5a, n = 1, R = H; 5b, n = 2, R = H; 6, n = 1, R = Me), respectively. On the other hand, the reaction of 1b with MeLi resulted in reductive cleavage of the disulfide bond to give the coordinatively unsaturated diiridium(III) complex [Ir(μ-SC₆H₂Me₂CH₂)(SMes)(PPh₃)]₂ (8), which was further converted into the bis(carbonyl) complex [Ir(μ-SC₆H₂Me₂CH₂)(SMes)(PPh₃)(CO)]₂ (9) upon addition of CO. Treatment of 2b with AgPF₆ led to the formation of the difluorophosphato-bridged complex [{Ir(μ-SC₆H₂Me₂CH₂)(PPh₃)(XyNC)}₂(μ-PF₂O₂)][PF₆] (10). The structures of the thiairidaindan complexes 2b, 4a, 5a, 7a and 8–10 have been determined by X-ray crystallography.