SYNTHESIS AND SPECTROSCOPIC STUDY OF PENTACARBONYL(ETA(2)-TETRACYANOETHYLENE) METAL(0) COMPLEXES OF THE GROUP 6B ELEMENTS

Pentacarbonyl(eta(2)-tetracyanoethylene) metal(0) complexes of chromiu m, molybdenum and tungsten have been synthesized by the photochemical reaction of hexacarbonyl metal(0) with tetracyanoethylene in toluene a t room temperature. The complexes were purified by chromatography and recrystallization, and characterized by UV-visible, IR and C-13 NMR sp ectroscopy. Tetracyanoethylene is symmetrically bonded to the M(CO)(5) unit through its carbon-carbon double bond as an eta(2)-ligand. The s pectral data are discussed in terms of the metal --> ligand pi interac tion.