An accurate X-ray diffraction study of Vaska's compound, trans-IrCl(CO)(PPh 3) 2, including resolution of the carbonyl/chloride disorder problem

Abstract

Vaska's compound, trans-IrCl(CO)(PPh 3) 2, crystallizes in the centrosymmetric triclinic space group P 1 , ( C 1 i ; No. 2) with a 9.2076(10), b 9.6458(16), c 10.4601(11) Å, α 72.290(11), β 89.597(10), γ 69.568(11)°, V 824.17(18) Å 3 and Z = 1. A complete shell of data for 2θ 4.5–50.0° (Mo- K α radiation) was collected on a Syntex P2 1 automated four-circle diffractometer and the structure was solved and refined to R F 1.7% and R wF 2.1% for 2920 independent data. The trans-IrCl(CO)(PPh 3) 2 molecule lies at a site of C i ( 1 ) symmetry and thereby suffers from disorder of CO and Cl ligands; the crystal is isomorphous with trans-Ir(CH 3)(CO)(PPh 3) 2 and presumably with trans-RhCl(CO)(PPh 3) 2. The chloride ligand and atoms of the CO ligand have been clearly resolved; metal-ligand distances are IrP 2.330(1) Å, IrCl 2.382(3) Å and IrCO 1.791(13) Å, with CO 1.161(18) Å and IrCO 175.1(12)°.