A Transient Infrared Spectroscopy Study of Coordinatively Unsaturated Ruthenium Carbonyls

Article abstract of DOI:10.1021/ja00191a009

Transient infrared spectroscopy is used to study coordinatively unsaturated Ru(CO)x products formed by excimer laser photolysis of gas-phase Ru(CO)5.Both Ru(CO04 and Ru(CO)3 are photoproducts of 248- and 351-nm irradiation of Ru(CO)5.This is the first report of direct observation of unsaturated Ru(CO)x species.Unlike the well-known Fe(CO)4 fragment, the high reactivity of the Ru(CO)x species has precluded their observation in cryogenic studies.The rate constants for reaction of Ru(CO)4 and Ru(CO)3 with CO are (2.8 +/- 0.8) * 10^-11 and (7.6 +/- 0.3) * 10^-11cm³molec^-1s^-1, respectively.These rate constants are ca. 10³ greater than that for the reaction of Fe(CO)4 with CO and can be rationalized in terms of the spin states of the reactants and products.Formation of a dinuclear complex, Ru2(CO)9, is also observed.Comparison of the distribution of M(CO)x fragments at different UV photolysis wavelengths has implications for the relative bond dissociation energies for carbonyl ligands on a ruthenium versus an iron center.