(μ-2,2',2'',2'''-{[Pyrazine-2,3,5,6-tetra-yltetra-kis(methyl-ene)]tetra-kis(sulfanedi-yl)}tetra-acetato)bis-[aqua-nickel(II)] hepta-hydrate.

Reaction of the ligand 2,2',2'',2'''-{[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(sulfanedi-yl)}tetra-acetic acid ( H 4 L1 ), with NiCl 2 leads to the formation of a binuclear complex, (μ-2,2',2'',2'''-{[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(sulfanedi-yl)}tetra-acetato-κ 5 O , S , N 1 , S ', O ':κ 5 O '', S '', N 4 , S ''', O ''')bis[aqua-nickel(II)] hepta-hydrate, {[Ni 2 (C 16 H 16 N 2 O 8 S 4 )(H 2 O) 2 ]·7H 2 O} ( I ). It crystallizes with two half mol-ecules in the asymmetric unit. The complete mol-ecules are generated by inversion symmetry, with the center of the pyrazine rings being located at crystallographic centres of inversion. The ligand coordinates two Ni II ions in a bis-penta-dentate manner and the sixfold coordination sphere of each nickel(II) atom (NiS 2 O 3 N) is completed by a water mol-ecule. The complex crystallized as a hepta-hydrate. The binuclear complexes are linked by O water -H⋯O carbon-yl hydrogen bonds, forming layers parallel to the (101) plane. This layered structure is additionally stabilized by weak C-H⋯O hydrogen bonds. Further O-H⋯O hydrogen bonds involving binuclear complexes and solvent water mol-ecules, together with weak C-H⋯S hydrogen bonds, link the layers to form a supra-molecular framework.