Effects of phosphine and phosphite substituents on metal–ligand bonding. The crystal and molecular structure of cis-dichloro(triethylphosphine)(triphenyl phosphite)platinum(II)

Abstract

The molecular structure of cis-[PtCl₂(PEt₃){P(OPh)₃}] has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P2₁/n, with a= 8.614. b= 37.100, c= 9.207 Å, β= 116.21° and Z= 4. The structure has been solved by the heavy-atom method and refined to R 0.034 for 4 206 diffractometric intensity data. The crystals contain discrete molecules, with platinum in tetrahedrally distorted square-planar co-ordination. The Pt–P(OPh)₃ and Pt–PEt₃ bond lengths are 2.182(2) and 2.269(1)Å. The Pt–Cl distances [2.344(2)Åtrans to P(OPh)₃ and 2.355(2)Åtrans to PEt₃] indicate that the trans influence of P(OPh)₃ is weaker than that of PEt₃. It is shown that the platinum(II)–ligand bond lengths in complexes with cis-Cl₂P₂ donor sets are related to the electronic properties of the substituents at the phosphorus atoms. The observed variations in the bond lengths are discussed in terms of σ- and π-electronic effects.