Structure and magnetism of coordination polymers containing dicyanamide and tricyanomethanide

Coordination polymers containing dicyanamide (N(CN)(2)(-), dca) or tricyanomethanide (C(CN)(3)(-), tcm) bridging ligands are described from the perspective of their structure and magnetism. The binary compounds alpha-M(dca)(2) form an isostructural series (M = Cr, Mn, Fe, Co, Ni, Cu) having a single rutile-like network that involves mu(1,3,5)-dca bridging. They display quite diverse types of long-range magnetic order viz. canted-spin antiferromagnets (Cr, Mn, Fe), ferromagnets (Co, Ni, Cu). An up-to-date review is given of the diverse range of physical measurements made on the alpha-M(dca)(2) Series together with interpretations for the different net exchange coupling and consequent 3D order. The doubly interpenetrating rutile network M(tcm)(2) series generally do not show long-range order except for a few members at very low temperatures. The 'mixed' self-penetrating network compounds M(dca)(tcm) do show long-range order (M = Co, Ni), albeit at lower T, values than for the M(dca)(2) parents. Modification of the M-dca networks is possible by incorporation of coligands into the structures. Ternary species of type M(dca)(2)(L)(n), where L is a terminal (e.g. pyridine, MeOH) or a bridging (e.g. pyrazine, 4,4-bipyridine) coligand, display a diverse range of 1D, 2D and 3D structural types. With a few exceptions, the large number of compounds structurally characterised contain mu(1,5)-dca bridging and display very weak antiferromagnetic coupling (J < ca. - 1 cm(-1)), typical of this bridging mode. Compounds such as Mn(dca)(2)(pyrazine) display a magnetic phase transition at low temperatures. This is also the case in the isostructural 2D layer compounds M(dca)(2)(H2O) - phenazine (M = Fe, Ni) which, perhaps not surprisingly, do not have coordinated phenazines but, rather, phenazines intercalated between layers of M(dca)(2)(H2O) in which mu(1,3,5) and mu(1,5)-dca bridging exists. Anionic networks of types M(dca)(3)(-) and M(dca)(4)(2-) formed by templation around cations of the organic (e.g. Ph4E+, R4N+) or inorganic (M(2,2'-bipyridine)(3)(2+)) types are described.