Synthesis and crystal and electronic structures of the dinuclear platinum compounds [PEtPh3]2[Pt2(μ-PPh2)2(C6F5)4] and [Pt2(μ-PPh2)2(C6F5)4]:: A computational study by density functional theory

The electrolytic behavior of the dinuclear complexes [NBu4](2)[MM'(mu-PPh2)(2)(C6F5)(4)] (M = M' = Pt (1), Pd (1a); M = Pt, M' = Pd (1b)) has been studied, showing electrochemically irreversible oxidation and related reduction processes. The chemical oxidation of the binuclear compound for M = M' = Pt, results in the formation of the binuclear Pt(III) compound [Pt-2(mu-PPh2)(2)(C6F5)(4)]. The crystal structure analysis of both complexes has been carried out, showing very similar structures with similar Pt-C and Pt-P distances and analogous skeletons. However the Pt-Pt distances are very different, 3.621(1) Angstrom for the Pt(II) compound and 2.7245(7) Angstrom for the Pt(III) derivative (as are the parameters geometrically related to this Pt-Pt distance), suggesting that, in the Pt(III) compound, then is a strong Pt-Pt bond. Results of DFT calculations on [Pt-2(mu-PH2)(2)(C6F5)(4)](n-) (n = 2, 0) agree very well with the crystallographic data and indicate that, in the Pt(III) compound, there is approximately a single sigma bond between the metal atoms.