Crystal and molecular structure of di-µ-chloro-[dichlorobis(trimethylarsine)]platinum(II); a quantitative assessment of the trans-influence of the trimethylarsine ligand

Abstract

Crystals of Pt2Cl4(AsMe3)2 are monoclinic, space group P21/n, a= 10·39, b= 11·84, c= 6·74 Å, β= 94·33°. The dimeric molecule consists of two square-planar platinum moieties sharing an edge, with the platinum atoms bridged unsymmetrically by two chlorine atoms. The crystal site symmetry is (Ci), but the molecule approximates very closely to 2/m(C2h) point symmetry. The Pt–Cl bond length trans to arsenic is 2·39 Å, longer than the two normal Pt–Cl bond lengths by ca. 0·1 Å, while the Pt–As bond length of 2·31 Å is much shorter than expected. These observations are a consequence of the strong trans-influence of trimethylarsine.