FeNCN and Fe(NCNH)2: Synthesis, Structure, and Magnetic Properties of a Nitrogen-Based Pseudo-oxide and -hydroxide of Divalent Iron

The synthesis, structure, and magnetic properties of the two monohydrocyanamide and carbodiimide representatives such as Fe(NCNH)2 and FeNCN, was reported. X-ray power diffraction (XRPD) was utilized to show that both materials are crystallographically phase-pure, and the new compounds are isomorphous with M(NCNH)2 and MNCN. The cynamide core of the HNCN- unit is found to be practically linear with 173.7(12)° and the monohydrocyanamide anions are arranged diagonally within the ab plane. The results show that both Fe-N-Fe and Fe-NCN-Fe bridges promote the formation of a magnetic coupling between adjacent spin centers. HNCN- is found to be noncentrosymmetric and totally bonds with four atoms, while NCN2- is centrosymmetric and bonds to three Fe atoms on each side.