Formation of organometallic xenon complexes in conventional fluids: A time-resolved infrared (TRIR) study of the photochemistry of W(CO)5(4AcPyr) (4-AcPyr=4-Acetylpyridine) in perfluoromethylcyclohexane (PFMCH)

Abstract

The photochemistry and photophysics of W(CO)5(4-Acpy) in perfluoromethylcyclohexane (PFMCH) has been investigated using fast time-resolved infrared spectroscopy (TRIR). Analysis of these TRIR data shows that rradiation (400 nm) of W(CO)5(4-Acpy) in PFMCH results in the formation of a metal-to-ligand charge transfer (MLCT) excited state which decays (τ =330 ns) to reform mainly the parent and a small amount of a new photoproduct. The production of this new photoproduct is supported by the use of global analysis and assigned to the formation of W(CO)5(PFMCH). W(CO)5(PFMCH) is not stable and reacts with residual water to form (τ = 5 μs) W(CO)5(H2O). In the presence of Xe, irradiation of W(CO)5(4-Acpy) again results in formation of an MLCT excited state but under these conditions it decays slightly faster (τ =245 ns) which is consistent with the formation of W(CO)5(Xe). Global analysis supports the formation of W(CO)5(Xe) which is more stable than W(CO)5(PFMCH) and reacts more slowly (τ = 12 μs) to form W(CO)5(H2O).