Resonance Raman and Emission Investigation of the MLCT Transition in Pt(PEt₃)₂(C⋮CH)₂

Abstract

Resonance Raman spectra including absolute Raman cross section measurements were acquired with excitation wavelengths within the MLCT absorption band of [Pt(PEt 3 ) 2 (C⋮CH) 2 ]. The absorption and resonance Raman cross sections were simultaneously modeled with time-dependent wave packet calculations to give an estimate of the vibrational reorganizational energies and initial structural changes of the excited state. We compare our results for [Pt(PEt 3 ) 2 (C⋮CH) 2 ], which contains no phenyl groups, with previous results for [Pt(dppm) 2 (PhC⋮C) 2 ], which contains a number of phenyl groups. The predominant nominal C⋮C stretch reaction coordinate and the vibrational reorganizational energies are significantly altered in the initial excited state by the absence or presence of the aromatic substituents, and we semiquantitatively estimate these changes.