Geometrically distorted and redox-active organometallic iridium complexes containing biphenyl-2,2′-diyl

Article abstract of DOI:10.1021/om00003a018

C-C bond cleavage of biphenylene by an Ir(I) complex via an oxidation addition generates the biph (=biphenyl-2,2′-diyl) ligand. The resulting compound is treated with PPh₃ to give [Ir(PPh₃)₂(biph)Cl], having a 16 e five-coordinate structure lying between Y and T geometries, being closer to a Y, which is rationalized on theoretical grounds. The complex [Ir(PMe₃)₃-(biph)Cl] can be oxidized quasi-reversibly to an Ir(IV) species. Oxidation with NOBF₄ gives the unusual Ir(IV) boryl compound [Ir(PMe₃)₃(biphBF)Cl]⁺, which has been isolated and structurally characterized. Extended Hückel (EHT) calculations suggest that the easy oxidation of the {Ir(biph)} system is associated with the presence of a high-lying Ir d_yz orbital. The {Ir(biph)} fragment is remarkably stable; only Br₂ is able to cleave the Ir-C bonds.