PHOTOCHEMICAL-REACTIONS OF TRANSITION-METAL-ORGANYL COMPLEXES WITH OLEFINS .5. CARBONYL(ETA(4)-DIENE-ETA(5)-2,4-DIMETHYL-2,4-PENTADIENYL) MANGANESE COMPLEXES

Tricarbonyl(eta-5-2,4-dimethyl-2,4-pentadienyl)manganese (1) reacts with Z-1,3-pentadiene (A) and with 1,3-cyclohexadiene (B) upon UV irradiation not to the expected [4 + 5]-cycloadducts, but by simple CO substitution to carbonyl(eta-5-2,4-dimethyl-2,4-pentadienyl)(eta-4-Z-1,3-pentadiene)manganese (2A) and carbonyl(eta-4-1,3-cyclohexadiene)(eta-5-2,4-dimethyl-2,4-pentadienyl)manganese (2B). The thermolabile, dark red complexes were characterized by IR and H-1-NMR spectroscopy. The crystal and molecular structure of 2B was determined by X-ray structure analysis. In 2B the coordinated carbon atoms of the two hydrocarbon ligands form planes with a dihedral angle of 10.6-degrees.