Cobalt diphosphonate with a new double chain structure exhibiting field-induced magnetic transition

A cobalt diphosphonate Co(H2O){C5H5N–CH2CH(OH)(PO3)(PO3H)} (1) has been synthesized under hydrothermal conditions. It shows a novel type of double chain structure in which one of the two CPO3 terminus caps on top of the {Co2(µ-O)2} dimer while the other connects the adjacent {Co2(µ-O)2} dimers into a chain. The magnetization measurements reveal that dominant antiferromagnetic interactions are mediated between the magnetic centers and the compound experiences a field-induced magnetic transition at low temperature with Hc of ca. 15 kOe at 1.8 K.