MATRIX PHOTOCHEMISTRY OF RU(CO)(2)(PME(3))(2)H-2 AND RU(CO)(3)(PME(3))(2) - FORMATION OF RU(CO)(2)(PME(3))(2)CENTER-DOT-CENTER-DOT-CENTER-DOT-S (S=AR, CH4, XE)

The photochemical reactions of Ru(CO)(2)(PMe(3))(2)H-2 (I) and Ru(CO)(3)(PMe(3))(2) (II) have been studied in low-temperature Ar, CH4, and Xe matrices by IR and UV-visible spectroscopy. UV photolysis (lambda > 200 nm) of I and II results in the formation of Ru(CO)(2)(PMe(3))(2)...S (S = matrix host), which shows a distinctive UV-visible absorption band with lambda(max) dependent on S (Ar, 423 nm; CH4, 385 nm; Xe, 352 nm). The reactions are partially reversed by irradiation with lambda > 360 nm. (CO)-C-13 isotopic labeling studies and trapping experiments in H-2-doped and N-2-doped Ar and CO matrices prove that the intermediate is a dicarbonyl species. In the structure proposed for RU(CO)(2)(PMe(3))(2)...S, the C-Ru-C bond angle must exceed 130 degrees.