Transient infrared spectroscopy is used to study coordinatively unsaturated Ru(CO)xproducts formed by excimer laser photolysis of gas-phase Ru(CO)5. Both Ru(CO)4and Ru(CO)3are photoproducts of 248- and 351-nm irradiation of Ru(Co)5. This is the first report of direct observation of unsaturated RufCO)xspecies. Unlike the well-known Fe(CO)4fragment, the high reactivity of the Ru(CO)xspecies has precluded their observation in cryogenic studies. The rate constants for reaction of Ru(CO)4and Ru(CO)3with CO are (2.8 ± 0.8) X 10-11 and (7.6 ± 0.3) X 10-11 cm-1molec-l s-1 respectively. These rate constants are ~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.
ASJC Scopus subject areas
- Colloid and Surface Chemistry