Iridium(III)cis-dihydrido complexes with 3,6-bis(2′-pyridyl)pyridazine. Crystal structure of the pyridazinyl complex [{IrH2(PPh3)2}2{µ-C4HN2(C5H4N)2-3,6}]PF6

Abstract

The complexes [IrH₂(Me₂CO)₂(PPh₃)₂]X (X = PF₆ or SbF₆) react with 3,6-bis(2′-pyridyl)pyridazine, dppn, in dichloromethane at 20 or 0 °C. At 20 °C the resulting products are the mononuclear species [IrH₂(dppn)(PPh₃)₂]X only, while at 0 °C, in addition the salts dppn·HX (X = PF₆ or SbF₆) and the homobinuclear complexes [{IrH₂(PPh₃)₂}₂{µ-C₄HN₂(C₅H₄N)₂-3,6}]X form. The structure of the dichloromethane solvate of the latter (X = PF₆) has been determined by X-ray diffraction methods. Crystals are triclinic, space group P, with a= 14.014(4), b= 22.781(8), c= 14.328(3)Å, α= 108.58(4), β= 68.79(5), γ= 99.04(5)°, and Z= 2. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.052 for 6 725 observed reflections. The structure consists of binuclear cationic complexes, of PF₆^– anions, and of dichloromethane molecules of solvation. The cation has imposed C_i symmetry, so that the organic ligand, chelating on its opposite sides both metals through three nitrogen and one carbon atoms, must be disordered and statistically distributed in two positions with the carbon atom bonded to both metals. The distorted octahedral co-ordination around each Ir atom is completed by two P atoms from PPh₃ ligands in trans positions and by two terminal hydrides in cis positions.