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

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)](infinity) (1) and {[M(CAN)2(pyz)(H2O)(2)]center dot 2H(2)O}(infinity) (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]center dot(4,4'-bipy)}(infinity) (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 alpha-Po networks by interaction with the aqua ligands.