W0216

Interactions of Pt(+2) with a Rigid Asymmetric Diene. John C. Woolcock & Bryan M. Craven, Chemistry Department, Indiana University of Pennsylvania, Indiana, PA 15705

Dibromo(eta-4-bicyclo[3.2.1]octa-2,6-diene)platinum(II) has been synthesised and its crystal structure has been determined. The hydrocarbon ligand consists of a 7-ring with a bridging methylene group that confers rigidity. The two olefin groups are different in that, together with the bridging methylene, one is in a 5-ring while the other is in a 6-ring. The Pt-diene interactions are of interest because the olefins are necessarily different. In a related molecule where the olefins were both in 6-rings (Woolcock, Niederhut & Craven, Austral. J. Chem., 1996, 49, 977-980), they were found to be related by crystallographic twofold symmetry. In the nonsymmetric molecule, the Pt-C distances are 2.16 and 2.18 Å for the olefin in the 5-ring and 2.23 and 2.29(2) Å for the other. The shorter distances are with an olefin that almost symmetrically straddles the plane of the PtBr2 group. The olefin making longer distances has one C atom close to the PtBr2 plane and the other well displaced from it. The crystal structure is orthorhombic, space group P2(1)2(1)2(1) with Z=4. X-ray data (CuK) were measured for two Friedel-related octants and an analytic absorption correction was applied (mu=36.6mm**-1). Structure refinement including the double octant gave R(F)=0.05.