Activation of the M-CO Bond in Transition Metal Complexes. CO Substitution Reactions in Di-, Tri- and Tetra-nuclear Metal Carbonyl Compounds Catalyzed by [Fe(CO)2(h5-C5H5)]2

The catalytic activity of [Fe(CO)2(η5-C5H5)]2 (hereafter [FeCp]2) in the CO substitution reactions has been explored in a number of systems involving binary and organometallic carbonyl complexes of two, three and four nuclearity. The results point out the versatility of [FeCp2] in promoting CO substitution with various Lewis bases where improved selectivity and yields of the substituted products have been achieved. The [FeCp]2 catalyzed reaction between [Fe3(CO)8(PhC2Ph)2] (black isomer) and P(OMe)3 afforded, at room temperature, two isomeric monosubstituted products, whose solution structures and dynamics have been elucidated by NMR spectroscopy. It is noteworthy that no substitution products could be obtained in the absence of the catalyst even at elevated temperatures.