Nickel coordination compounds of the cyanamido squarate ligand. The crystal structures of the 2,4-bis(cyanamido)cyclobutane-1,3-dione dianion (2,4-NCNsq2−) and of three polymers with general formula [Ni(Him)x(H2O)4 − x(2,4-NCNsq) · yH2O]n (x =Â

Reactions of nickel (II) with imidazole and 2,4-NCNsq2− yield new complexex presenting an end-on coordination by the two nitrile nitrogen atoms in a bridging mode.