Copper diphosphonates with zero-, one- and two-dimensional structures: ferrimagnetism in layer compound Cu3(ImhedpH)(2).2H2O [ImhedpH4=(1-C3H3N2)CH2C(OH)(PO3H2)2].

Reactions of CuSO4 with 2-(1-imidazole)-1-hydroxy-1,1'-ethylidenediphosphonic acid (ImhedpH4) under hydrothermal conditions at different temperatures lead to four new metal phosphonates: Cu(ImhedpH3)2(H2O).2H2O (), Cu(ImhedpH3)2 (), Cu3(ImhedpH2)2(ImhedpH3)(2).4H2O (), and Cu3(ImhedpH)(2).2H2O (). Compounds and have mononuclear structures in which the Cu atoms adopt square pyramidal and square planar geometries, respectively. In compound , a chain structure is observed where the Cu3(ImhedpH2)2(ImhedpH3)2 trimer units are connected by edge-sharing of the {Cu2O5} square pyramids. Compound exhibits a layer structure made up of Cu3(ImhedpH)2 trimer units. The connection of trimers through corner-sharing of {Cu1O4} and {CPO3} tetrahedra results in a two-dimensional layer containing 8- and 16-membered rings. The imidazole groups are grafted on the two sides of the layer. Magnetic studies reveal that ferromagnetic interactions are mediated in , while for compound , ferrimagnetism is observed below 5.8 K.