Spin Crossover and Light-induced Excited Spin-state Trapping Observed for an Iron(II) Complex Chelated with Tripodal Tetrakis(2-pyridyl)methane

A novel iron(II) complex [Fe(py4C)2][Fe(py4C)(NCS)3]2 was synthesized, where py4C stands for tetrakis(2-pyridyl)methane. Spin crossover occurred at 161 K (T1/2). Light-induced excited spin-state trapping was observed when irradiated with 532 nm at 10 K, and the conversion was 89%. The relaxation took place at 58 K on heating.