Crystal structure of dichloro-di-µ-(pentamethylbicyclo[2,2,0] hexa-2,5-dienylmethyl) diplatinum(II)

Abstract

A structural analysis of a dimeric pentamethylbicyclo[2,2,0] hexa-2,5-dienylmethyl derivative of platinum(II)[PtCl(C₁₂H₁₇)]₂ has been completed by three-dimensional, single-crystal X-ray methods. The complex, crystallises in the monoclinic space group C2/c, with a= 13·33, b= 10·88,c= 17·60 Å, β= 100·6°, and Z= 4. The structure was solved by Patterson and Fourier syntheses, and refined by least-squares methods to R 0·055 for the 1352 independent non-zero reflexions. The average estimated standard deviations in the observed bond lengths are: Pt–Cl 0·007, Pt–C 0·02 and C–C 0·03Å.

The dimeric molecule has C₂ symmetry. A dehydro-hexamethyl Dewar benzene ligand bridges two platinum atoms, giving a platinum–platinum separation of 3·262 ± 0·002Å; the dehydro-hexamethyl Dewar benzene ligands are co-ordinated to one platinum atom via a σ-bond to the methylene carbon, and to the other platinum atom via two π-olefin bonds. The relative trans influences of an olefin and of a σ-bonded carbon are discussed.