catena-Poly[[[diaqua(tetramethylethylenediamine-κ2 N,N′)nickel(II)]-μ-sulfato-κ2 O:O′] monohydrate]

The title compound, {[Ni(SO4)(C6H16N2)(H2O)2]·H2O}n, contains a NiII atom that is coordinated nearly octahedrally by a chelating tetraethylenediamine (tmeda) ligand, two water molecules in a cis arrangement and two O atoms of two sulfate anions in a trans arrangement. The sulfate anions act as μ2-bridging ligands leading to a chain structure of alternating NiO4N2 octahedra and SO4 tetrahedra parallel to [001]. The polymeric chains are linked by O—H⋯O hydrogen bonds between coordinating water molecules and sulfate anions to give double strands. There is a lattice water molecule which is also involved in O—H⋯O hydrogen bonding between adjacent [Ni(SO4)(tmeda)(H2O)2] chains.

The title compound, { [Ni(SO 4 )(C 6 H 16 N 2 )(H 2 O) 2 ]ÁH 2 O} n , contains a Ni II atom that is coordinated nearly octahedrally by a chelating tetraethylenediamine (tmeda) ligand, two water molecules in a cis arrangement and two O atoms of two sulfate anions in a trans arrangement. The sulfate anions act as 2bridging ligands leading to a chain structure of alternating NiO 4 N 2 octahedra and SO 4 tetrahedra parallel to [001]. The polymeric chains are linked by O-HÁ Á ÁO hydrogen bonds between coordinating water molecules and sulfate anions to give double strands. There is a lattice water molecule which is also involved in O-HÁ Á ÁO hydrogen bonding between adjacent [Ni(SO 4 )(tmeda)(H 2 O) 2 ] chains.

Experimental
Crystal data [Ni(SO 4 Table 1 Hydrogen-bond geometry (Å , ).  Each of the water molecules attached to nickel forms an intrachain hydrogen bond of the type R 1 1 (6) or R 1 1 (6) to a sulfate oxygen atom. The lattice water molecule, which acts as a linker between the chains, forms two hydrogen bonds of the type R 1 1 (2) to sulfate oxygen atoms and a D 1 1 (2) hydrogen bond to a coordinating water molecule. Additonally, there are hydrogen bond motifs of the type R 2 2 (12) which are formed between coordinating water molecules and sulfate oxygen atoms of neighbouring chains. As a result of these interchain hydrogen bridges, double strands are formed which propagate parallel to [001]. The arrangement of the double strands corresponds to a distorted hexagonal rod packing.
Experimental 3.7 ml (46 mmol) of pyridine were added to a solution of 2.0 g (7.6 mmol) of nickel sulfate hexahydrate in 50 ml of water. 1.2 ml (8.0 mmol) of tmeda were added and all volatile compounds removed under reduced pressure at 333 K. The resulting solid was recrystallized from water and washed with ether to obtain the title compound in a yield of 85% (2.1 g).

Refinement
The hydrogen atoms of the tmeda ligand were positioned geometrically and were refined using a riding model with U(H) = 1.2 U eq (C). Hydrogen atoms of the water molecules were located from difference Fourier maps and were refined with O    Part of the hydrogen-bonding network (dashed lines) in the structure of compound (I). [Symmetry codes: i) x, y, -z+1; iii) -x, -y+1, z-0.5; iv) -x, -y + 1, z + 0.5.]

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.