SHORT-WAVELENGTH FLASH PHOTOLYTIC FRAGMENTATION OF RU3(CO)(12) IN THEPRESENCE OF CO AND COMPLEMENTARY EXPERIMENTS WITH RU(CO)(5) - A TIME-RESOLVED IR SPECTROSCOPIC STUDY

Short-wavelength (308 nm) photoinduced reactions of binary ruthenium c arbonyls in the presence of varying concentrations of carbon monoxide are investigated by means of flash photolysis (XeCl excimer laser) in combination with time-resolved IR spectroscopy. Photodissociation of C O from Ru-3(CO)(12)l yields the Ru-3(CO)(11) fragment in the CO-bridge d form. Beyond the known re-formation of the parent complex, this spec ies under CO atmosphere takes up a total number of three CO ligands to form a 1:1 mixture of Ru(CO)S and Ru-2(CO)(9) as the ultimately obser ved products. This process involves the intermediate formation of Ru-3 (CO)(12)(mu-CO), which decays by first-order kinetics with a rate cons tant of about 2.2 x 10(4) s(-1) at ambient temperature. Complementary studies with Ru(CO)(5) and (in situ generated) Ru-2(CO)(9) as starting materials provide insight into the mechanism by which Ru(CO)(5) is co nverted into Ru-3(CO)(12) and/or Ru-2(CO)(9), depending on the CO conc entration and the photolysis conditions. The solvated Ru(CO)4 fragment , the dinuclear Ru-2(CO)(8), and Ru-3(CO)(12)(mu-CO) are observed as t ransient species in addition to Ru-2(CO)(9), which is stable on the ti me scale of these experiments.