Synthesis of some pentanuclear platinum clusters [Pt5(CO)6(L)4]. The X-ray structure of [Pt5(μ-CO)5(CO)(PCy3)4]

[Pt5(μ-CO)5(CO)L4] (L = PPh31, PPh2Bz 2, AsPh33, PEt34, PCy35) have been synthesized by reacting [Pt3(μ-CO)3(PR3)3] with H2O2 (1 and 2), by reduction of cis-[PtCl2(CO)(PEt3)] with Zn dust (4), and by the Zn reduction of [Pt3(μ-CO)3(PCy3)3] in the presence of [PtCl2(CH3CN)2] (5). Complex 5 has not been observed previously and has been characterized by X-ray crystallography. Oxidation of the phosphine ligands with H2O2 is a new way to synthesize 1 and 2. The first complete NMR characterization of these complexes has also been achieved, and showed that these pentanuclear cluster complexes exhibit similar stereochemistries in solution and in the solid state. The observed 1JPt–Pt values do not have any correlation with the corresponding bond lengths, again pointing out the irregular behaviour of such parameter in Pt complexes.