A rare 2D structure of a novel Cu(II) dinuclear-based compound with dicyanamide and 4-nitropyridine-N-oxide as ligands

A new Cu(II) polymeric dicyanamide (dicyanamide = [N(CN)2]−, dca) with the ligand 4-nitropyridine-N-oxide (4npo), [Cu(dca)2(4npo)]n has been synthesised and structurally characterised. The Cu(II) ion has a slightly distorted square-pyramidal geometry with the basal plane formed by four nitrogen atoms of four different dca ligands and the apical position is formed by the oxygen atom of the 4npo ligand. The base structural unit is a dinuclear species formed by 2 Cu(II) and 2 end-to-end (μ1,5)-dca ligands with a Cu–Cu distance of 7.205 Å. The Cu(II) centres are further connected through single end-to-end (μ1,5)-dca bridging ligands to generate a 2D layered structure of dinuclear units. Within the layer short non-bridged Cu–Cu contacts of 4.059 Å occur.