Decoupling of the molecular spin-state and the crystallographic phase in the spin-crossover complex [Fe(ptz)6](BF4)2 studied by Raman spectroscopy

Raman spectra of the spin-crossover complex [Fe(ptz)6](BF4)2 (ptz = 1-n-propyl-tetrazole) have been recorded at visible and IR exciting wavelengths as a function of temperature down to 5 K. Distinct Raman markers were associated with the spin-state change and the crystallographic phase-transition of the compound. This allows us to demonstrate that the light-induced exited spin-state trapping (LIESST) and the reverse-LIESST effects as well as the thermal relaxation of the photo-induced phase occur without crystallographic phase change in contrast to the thermal spin-crossover.