X-ray study of the light-induced metastable state of a spin-crossover compound

Iron(II) complexes exhibiting thermal spin crossover may be converted from the 1A1 low-spin state to the 5T2 high-spin state by irradiation with green light (light-induced excited spin-state trapping, LIESST). The lifetime of the metastable LIESST state may be sufficiently long for X-ray diffraction study.