Abstract A new iron (II) spin-crossover compound containing a phosphane ligand has been synthesized and characterized by magnetic susceptibility, Mössbauer spectroscopy, and heat capacity and photomagnetic experiments. The [Fe (tppb) Br 2] complex [tppb= 1, 2, 4, 5- tetrakis (diphenylphosphanyl) benzene] exhibits a gradual spin conversion at T 1/2= 184 K, and displays at low temperature a partial photoconversion of the low-spin (LS) state into ...