Synthesis of Anionic Spin Crossover Complexes with Schiff Base like Ligands

The reaction of neutral iron(II) complexes of tetradentate Schiff base like ligands with the pseudohalogenides SCN – , OCN – , and CN – as monodentate axial ligands was investigated. In solution the formation of octahedral complexes could be confirmed and it was possible to follow a spin transition by T ‐dependent 1 H NMR spectroscopy. In the solid only pentacoordinate complexes were obtained and the X‐ray structure of five monoanionic pentacoordinate iron(II) complexes and an interesting trinuclear complex are discussed.