Synthesis and X-ray crystal structure of a tri-iridium cluster, [Ir3(CO)6(Ph)(µ3-PPh)(µ-dppm)]

Abstract

The reaction between [IrCI(CO)₂(CH₃C₆H₄NH₂-p)] and CH(PPh₂)₃ in the presence of CO and Zn yields [Ir₃(CO)₆(Ph)(µ³-PPh)(µ-dppm)](1)(dppm = Ph₂PCH₂PPh₂), an uncharacterised product, and [Ir₄(CO)₉{CH(PPh₂)₃}]. The solid-state structure of (1) has been established by X-ray crystallography. Complex (1) crystallises in space group P2₁/c with a= 11.811(3), b= 22.328(5), c= 17.864(4)Å, β= 99.51(2)°, and Z= 4. The structure was solved by direct methods and difference-Fourier syntheses and refined by block-matrix least-squares methods to R= 0.0476 (R′= 0.0511). The molecule contains a triangular array of iridium atoms capped by a phenylphosphido(2–) group. One edge of the iridium triangle is bridged by a dppm ligand and a phenyl group is σ-bonded to the third iridium atom. In addition, there are two carbonyl ligands terminally bound to each Ir atom.