New preparative access to and the crystal and molecular structures of cis-[PtCl2(CO)2]

cis-Dicarbonyldichloroplatinum(II) has been found to be the thermodynamically stable species arising from: (a) carbonylation of [NBu4]2[PtCl4] in the presence of AlCl3, (b) chlorination of [PtI2(CO)2]–[Pt2I4(CO)2] with SO2Cl2 under CO and (c) carbonylation of PtCl2; the crystal and molecular structures of cis-[PtCl2(CO)2] showed a short C–O distance [average 1.115(7)Å] and intermolecular Pt ⋯ Pt and C ⋯ Cl contacts of less than 3.4 Å.