Crystal and molecular structure of [IrH₃(Pme₂Ph)₂]₂ : a novel (μ-H)₂ bridged Ir^III dimer

Abstract

The preparation and characterization of the title compound are described. Crystals are orthorhombic, space group Pbca, with a 11.433(5), b 14.768(6), c 20.616(10) Å and Z 4. Diffraction data were recorded on a four-circle diffractometer. Least-squares analyses converged with R = 0.038 for 1897 unique data. Molecules are (pH), bridged dimers possessing strict crystallographic inversion symmetry. Metal atoms have a formal 16e^- configuration and are approximately octahedrally coordinated by four H (two bridging) and two phosphine ligands. The Ir-Ir distance [2.739(1) Å] is intermediate between those in (µ-H)(µ-Cl) and (µH)₃ bridged species. Ir-P distances [2.231(3) and 2.3132) Å, trans to bridging and terminal H atoms respectively] show the trans-influence of bridging H to be small, cf. terminal H. Molecules exhibit fluxional behaviour in solution.