Rhodium(III) and iridium(III) olefin complexes containing the tridentate ligand 1,6-bis(diphenylphosphino)-trans-hex-3-ene: crystal and molecular structure of trichloro-1,6-bis(diphenylphosphino)-trans-hex-3-eneiridium(III).

The olefin complexes RhCl₃(BDPH), RhClBr₂(BDPH), IrCl₃(BDPH), IrClBr₂(BDPH), IrCl(CH₃)I(BDPH), IrHCl₂(BDPH) and IrHBr₂(BDPH); BDPH = 1,6-bis(diphenylphosphino)-trans-hex-3-ene, have been prepared by oxidative-addition reactions of RhCl(BDPH) and IrCl(BDPH) and characterised by I.R. and ¹H NMR spectra. A single crystal X-ray determination of the structure of IrCl₃(BDPH) shows the crystals to be orthorhombic, a = 16.1636(13), b = 20.2927(7), c = 17.1916(6)Å, Z = 8, space group Pbca, ?_obs = 1.76, ?_calc = 1.77 g cm^?3. The structure was solved by conventional methods and refined by use of full-matrix least-squares equations to final residuals R = 0.041 and R_w = 0.052 for 2926 observed reflections.The complex is monomeric with an octahedral coordination geometry consisting of the tridentate olefin(phosphine)₂ BDPH ligand (arranged such that the phosphorus atoms are mutually trans, and the three chloride ligands. Distances observed are Ir-P 2.382, 2.389(2)Å, Ir-Cl 2.358, 2.387 (trans to olefin), 2.371(2)Å, Ir-C(olefin) 2.274, 2.277(10)Åf, C=C 1.352(14)Å. The olefin is inclined at an angle of 28° to the Ir, P(1), P(2), Cl(2) plane. The structure is compared and contrasted with the known structures of IrCl(BDPH) and IrH₂Cl(BDPH).