Structural class distribution forcis/trans-PtX2L2,X= halogen,L= neutral ligand the structures of two polymorphs ofcis-PtCl2(Bz2S)2

Abstract

The anhydrous complex of the rubidium hydrogen oxalate has been synthesized as single crystal and characterized by X-ray diffraction, IR spectroscopy and thermogravimetric study. The structure has been determined from data collected on a Kappa CCD diffractometer and shows the compound to be isostuctural with the potassium hydrogen oxalate [1]: it crystallizes in space group P21/c (Z=4) with the cell parameters a=4.2940(3), b= 13.6230(10), c=7.6689(5) and β=101.50(50)°, slightely different from those found by Hendricks [2]. The structure consists of layers formed by chains of one-edge-sharing rubidium polyhedra, running along the [001] direction and alternating layers of hydrogen oxalate groups, Hox, which are hydrogen bonded. The rubidium atom is sevenfold coordinated with two bridged-chelating Hox ligands and three bridgedmonodendate hydrogen oxalate. As expected, the anion group is non planar and is found to be twisted about the C-C bond with an angle of about 15°. It is due to the strong hydrogen bond which is usual in acid salt alkali metal and hydrogeno-carboxylates complexes [1][3][4][5]. This hydrogen bond O-H ....O’ which connects the hydrogen oxalate ions is asymmetric (O-HandH ...O’ distances are respectively 0.99 and 1.547A) and approximately linear (the O-H ...O’ angle is 176°). The IR spectrum shows the bands due to the free carboyl absorption and to oxalate salts as the bands of O-H streching modes and the thermal decomposition agrees with the XR and IR investigations.