The oxidative addition of diphenyl diselenide and ditelluride to tetrakis(triphenylphosphine)palladium

The oxidative addition of diphenyl diselenide to [Pd(PPh3)4] in dichloromethane results in the formation of a dinuclear complex [Pd2(SePh)4(PPh3)2] (1) and a mononuclear complex [PdCl(SePh)(PPh3)2] (2) that have been identified and characterized structurally by X-ray crystallography and 31P-NMR spectroscopy. The analogous reaction involving diphenyl ditelluride leads to a mixture of products. [Pd6Cl2Te4(TePh)2(PPh3)6]·1/2CH2Cl2 (3) can be isolated and its X-ray structure determined. While the oxidative addition of Ph2Se2 mainly involves the clevage of the Se–Se bond, that of Ph2Te2 indicates the rupture of both Te–Te and C–Te. Cumulative evidence shows that the choice of the central atom and the solvent also plays an important role in the oxidative addition. The final polynuclear complexes can be conceived to be formed from the mononuclear addition products by sequential condensation steps.