Coordination polymers of nitrocyanamide, O2NNCN−: synthesis, structure and magnetism

Abstract

Three new groups of coordination polymers have been synthesised containing the anionic ligand nitrocyanamide, O2NNCN− (CAN). These new compounds have been structurally characterised and their magnetic properties have been investigated and show very weak antiferromagnetic coupling without any long-range order. Three complexes were obtained using pyrazine as a co-ligand, namely [Cu(CAN)2(pyz)]∞ (1) and {[M(CAN)2(pyz)(H2O)2]·2H2O}∞ (M = Fe, 2Fe; M = Co, 2Co). Compound 1 forms a 2D (4,4) network containing both bridging pyrazine and CAN ligands with the latter adopting a N,O binding mode involving the terminal nitrogen atom. The Fe and Mn complexes 2 form 1D coordination polymers that are heavily hydrogen bonded to each other via coordinated and un-coordinated water molecules. Reaction of MCl2 with Ag(CAN) and 4,4′-bipyridine leads to the isomorphous complexes {[M(CAN)2(4,4′-bipy)(H2O)2]·(4,4′-bipy)}∞ (3) (M = Co, Fe, Mn) containing similar polymeric strands to those in the structure of 2. The interstitial bipyridine molecules in the structure of 3 give rise to two interpenetrating 3D hydrogen-bonded α-Po networks by interaction with the aqua ligands.