Molybdenum and tungsten complexes with carbon dioxide and ethylene ligands.

The first examples of stable metal complexes with coordinated ethylene and carbon dioxide ligands are reported. Reaction of tris(ethylene) complexes -M(CH)(PNP) (M = Mo and W; PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) with CO yields the corresponding, mixed -M(CH)(CO)(PNP) derivatives. X-ray studies reveal six-coordinate structures exhibiting η-ethylene and κ-C,O carbon dioxide coordination. Remarkably, the formation of the molybdenum CO adduct occurs also in the solid state at room temperature, under 4 bar of CO, in a nearly quantitative manner.