UC Berkeley

Two systems were studied using either a pump-probe spectroscopic technique or a density functional theory computational method. Ultrafast time-resolved infrared spectroscopy has been used to investigate the reactivity of V(CO)5, a doublet species, with silicon-hydrogen and carbon-hydrogen bonds. Using a ultraviolet pump pulse, a carbonyl was dissociated from V(CO)6 while dissolved in triethylsilane; subsequently, a broad bandwidth infrared pulse interrogated the system. On timescales less than 1 ns, vanadium pentacarbonyl does not appear to react. The second study used the Growing String Method incorporating density functional theory to examine the possible reaction mechanisms for the fluxional rearrangement of Fe3(CO)12 and Ru3(CO)12. Fluxional mechanisms have structurally identical reactants and products; the atoms swap positions with other atoms of the same element. The concerted bridge-opening, bridge-closing mechanism for the Fe3(CO)12 was calculated to have the lowest barrier of those tested at 0.777 kcal/mol; in this mechanism, all twelve carbonyl change position and the final structure is equivalent to the initial structure. At 4.285 kcal/mol, the next lowest energy barrier was calculated for the Cotton's Merry-Go-Round mechanism.