The structure of W(CO)5L (L = pyridine, piperidine) in the lowest ligand field excited state determined by fast time-resolved IR spectroscopy; unexpected C–O bond length changes

Abstract

The frequencies of the ν(CO) bands of W(CO)₅L (L = pyridine and piperidine) in the lowest ligand field (LF) excited states have been obtained by fast time-resolved IR spectroscopy of the species dissolved in low-temperature glasses, and the shifts from the ground state indicate that the C–O bonds lengthen on excitation, contrary to the interpretation of the pre-resonance Raman spectroscopy on the ground state.