Structure of PtCl 2[C 3H 4(C 6H 5) 2](C 5H 5N) 2 · [formula omitted] C 2H 5OH, a substituted cyclopropane complex of platinum

Abstract

The crystal and molecular structure of a 1,2-diphenylcyclopropane complex of platinum, PtCl 2[C 3H 4(C 6H 5) 2] (C 5H 5N) 2, has been determined from three-dimensional X-ray diffraction data. The crystal has symmetry consistent with space group P 1 (C i 1) with four molecules of the complex and two molecules of ethanol of crystallisation in a unit cell of dimensions a = 13.148(6), b = 14.052(7), c = 17.860(8) Å; α = 62.53(1), β = 108.25(3), γ = 114.69(3)°. The structure was refined by least-squares techniques to a conventional R-factor of 10.0% using 2804 reflections, collected using a four-circle diffractometer, for which F 2 ⩾ σ(F 2). The ethanol of crystallisation was highly disordered, and a satisfactory description was not obtained for it. There are two independent complex platinum molecules in the unit cell and, whilst the mode of attachment of the substituted cyclopropane is basically similar in the two molecules, there are significant differences between the observed geometries, and the two molecules are not equivalent. The platinum atoms in both molecules have two chlorine atoms trans in axial positions and two cis pyridine ligands in the equatorial plane; the coordination sphere is completed by the cyclopropane ligand which has two of its ring carbon atoms in the equatorial plane approximately equidistant from platinum and the third ring carbon atom considerably further away from platinum and slightly displaced from the equatorial plane. In one of the complex molecules, the angle subtended to platinum by the nitrogen atoms of the pyridine ligands is 92(1)° and the plane of one of the phenyl rings is perpendicular to the cyclopropane ring plane; in the other complex molecule, the corresponding N-Pt-N angle is 82(1)° and the planes of the phenyl and cyclopropane rings are not mutually perpendicular. The bonding of cyclopropaneto platinum was rationalised using a four-centre localised molecular orbital scheme.