Di-μ-nicotinato-κ2 N:O;κ2 O:N-bis­[aqua­(ethyl­enediamine-κ2 N,N′)(nicotinato-κN)cadmium(II)] dihydrate

The dinuclear mol-ecule of the title compound, [Cd(2)(C(6)H(4)NO(2))(4)(C(2)H(8)N(2))(2)(H(2)O)(2)]·2H(2)O, lies on an inversion centre and forms 12-membered (CdNC(3)O)(2) metallacycles with the two Cd(2+) ions bridged by two nicotinate ligands. Both Cd(2+) ions display coordination polyhedra with a distorted octa-hedral geometry that includes two pyridine N atoms from bridging and terminal nicotinate anions, two amine N atoms from chelating ethylene-diamine ligands, carboxylate O atoms from bridging nicotinate anions and water O atoms. Inter-molecular O-H⋯O and N-H⋯O hydrogen bonds result in the formation of a three-dimensional network, and π-π stacking inter-actions are observed between symmetry-related pyridine rings of bridging as well as terminal nicotinate anions (the centroid-centroid distances are 3.59 and 3.69 Å, respectively, and the distances between parallel planes of the stacked pyridine rings are 3.53 and 3.43 Å, respectively). The two methylene groups of the ethylene-diamine ligand are disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.