Thermal and Light‐Induced Spin Crossover to a Metastable Low‐Spin State in [Fe(mtz)6](CF3SO3)2

Abstract
Irradiation by red light at T ≲ 40 K induces the transition of the stable high‐spin state of 1 to a metastable low‐spin state, which, at T < 40 K, has a lifetime of days to weeks, The transition occurs via double intersystem crossing, 5T25E3T11A1. Compound 1 is only the second compound to show this effect. equation image