Abstract
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 (H4L1), with NiCl2 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-κ5 O,S,N 1,S',O':κ5 O'',S'',N 4,S''',O''')bis[aqua-nickel(II)] hepta-hydrate, {[Ni2(C16H16N2O8S4)(H2O)2]·7H2O} (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 NiII ions in a bis-penta-dentate manner and the sixfold coordination sphere of each nickel(II) atom (NiS2O3N) is completed by a water mol-ecule. The complex crystallized as a hepta-hydrate. The binuclear complexes are linked by Owater-H⋯Ocarbon-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.
Highlights
Tetrakis(sulfanediyl)}tetraacetic acid (H4L1), with NiCl2 leads to the formation of a binuclear complex, (-2,20,200,2000-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetraacetato-5O,S,N1,S0,O0:5O00,S00,N4,S000,O000)bis[aquanickel(II)] heptahydrate, {[Ni2(C16H16N2O8S4)(H2O)2]Á7H2O} (I)
The complete molecules are generated by inversion symmetry, with the center of the pyrazine rings being located at crystallographic centres of inversion
The binuclear complexes are linked by Owater— HÁ Á ÁOcarbonyl hydrogen bonds, forming layers parallel to the (101) plane
Summary
Symmetry codes: (i) Àx þ 1; Ày; Àz þ 1; (ii) Àx; Ày þ 2; Àz; (iii) Àx þ 1; Ày þ 1; Àz þ 1; (iv) x þ 1; y; z; (v) Àx; Ày þ 1; Àz; (vi) Àx þ 1; Ày þ 1; Àz; compared to ring N12/S4/C15/C16 /O8, which has an envelope conformation with atom S4 as the flap, ring Ni1/S2/C7/ C8/O4 is twisted on the Ni1—S2 bond, compared to ring Ni2/ S3/C11/C12/O6, which is twisted on the S3—C11 bond. In the crystal structure of I, binuclear nickel(II) complexes are linked by Owater—HÁ Á ÁOcarbonyl hydrogen bonds, forming layers parallel to the (101) plane (Fig. 3, Table 2). Weak C—HÁ Á ÁO hydrogen bonds are present (Table 2). Solvent water molecules are linked by O—HwaterÁ Á ÁO water hydrogen bonds to form ribbons propagating along the b-axis direction that consist of eight and twenty-four membered rings of the R44(8) and R1102(24) types (Fig. 4 and Table 2). Additional O—HwaterÁ Á ÁOcarbonyl hydrogen bonds involving the binuclear complexes and solvent water molecules, together with weak C—HÁ Á ÁS hydrogen bonds, link the layers to form a supramolecular framework (Fig. 5)
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