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)

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).