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 NOEF4 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 dyz orbital. The (Ir(biph)} fragment is remarkably stable; only Br2 is able to cleave the Ir-C bonds.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry