Structure and Magnetism of 3D Anionic Metal Dicyanamide (MePh₃P)[M(dca)₃] (M = Fe, Co, Ni) and (EtPh₃P)[M(dca)₃] (M = Mn, Co, Ni) Networks

The structures of (MePh₃P)[M(dca)₃] (M = Fe, Co, Ni and dca = dicyanamide, N(CN)₂^-) are isomorphous and contain anionic [M(dca)₃]^- networks in which octahedral metal ions are bridged by bidentate μ_1,5 dca anions, to generate three-dimensional (3D) five-connected networks. The structures of (EtPh₃P)[M(dca)₃] (M = Mn, Co, Ni) are also isomorphous and contain similar anionic networks to the MePh₃P⁺ structures. In both sets of structures, the cations appear to perform a templating function and lie in pairs within cavities in the anionic network. These cation pairs show pseudo-6-fold phenyl embraces. No long-range magnetic ordering intrinsic to these materials was observed, although traces of the ferromagnets α-[Co(dca)₂] and α-[Ni(dca)₂] were observable in very small applied fields, at 9 and 21 K, respectively.