Compounds containing platinum–carbon bonds. Part IV. Crystal and molecular structures of trans- and cis-dichloro(l,3-diphenylimidazol-idin-2-ylidene)(triethylphosphine)platinum(II)

Abstract

The crystal structures of the trans(I) and cis(II) isomers of [PtCl₂{C(PhNCH₂)₂}(PEt₃)] have been determined by X-ray diffraction methods. The structural models were refined by full-matrix least-squares, both to R 0·048 [(I), 2356 and (II), 1822 independent reflections measured on a diffractometer]. Crystal data are : (I), triclinic, space group P, a= 13·961(6), b= 11·782(4), c= 10·659(5)Å, α= 92·98(3), β=125·29(3), γ= 114·54(3)°, Z= 2; (II), orthorhombic, space group Pnam, a= 15·991(2), b= 8·601(2), c= 16·703(2)Å, Z= 4.

Crystals of both compounds are built of discrete monomeric molecules, in which the co-ordination around the platinum atom is square planar. In (I) selected bond lengths are: Pt–Cl 2·302(10), Pt–P 2·291(4), and Pt–C 2·020(16)Å; in (II) they are Pt–Cl (trans to C) 2·362(3), Pt–Cl (trans to P) 2·381(3), Pt–P 2·234(3), and Pt–C 2·009(13)Å. These results indicate that the order of the Pt–C bonds is little greater than unity, and that the trans-influence of the carbene ligand is similar to that of phosphine and appreciably greater than that of chlorine.