Effect of Pressure on the Vibronic Luminescence Spectrum of a trans-Dioxo Rhenium(V) Complex

Luminescence spectra of trans -ReO 2 (tmen) 2 Cl (tmen = tetramethylethylenediamine, (H 3 C) 2 N(CH 2 ) 2 N(CH 3 ) 2 ), show pressure-dependent vibronic structure involving the high-frequency O Re O stretching mode in the 3 E g → 1 A 1g transition ( D 4 h point group). Its frequency and the intensity distribution within the progression are both pressure dependent. The ground-state O Re O frequency increases from 868 cm -1 at ambient pressure to 887 cm -1 at 51 kbar. The influence of pressure on the shape and relative positions of the ground and emitting state potentials is determined.