Synthesis, Crystal-Structure Determination and Magnetic Properties of Two New Transition-Metal Carbodiimides: CoNCN and NiNCN

Synthesis, structure determination, and magnetic properties are reported for the metastable and crystal-chemically isotypic phases cobalt carbodiimide, CoNCN, and nickel carbodiimide, NiNCN, adopting the hexagonal system and space group P63/mmc (NiAs type) with interatomic distances of Co−N = 2.17 Å and Ni−N = 2.12 Å and an octahedral coordination of the transition-metal ions; the NCN2- units reveal the carbodiimide shape with two CN double bonds. The low-susceptibility data go back to strong antiferromagnetic spin−spin coupling, similar to the behavior of the electronically related oxides CoO and NiO.