Tris(ethylenediamine-κ2 N,N′)nickel(II) naphthalene-2,7-disulfonate

The NiII atom in the title salt, [Ni(C2H8N2)3](C10H6O6S2), is chelated by three ethylenediamine ligands in an octahedral geometry. The cation and anion are linked by N—H⋯O hydrogen bonds into a three-dimensional network. One of the two –SO3 groups is disordered over two positions in a 1:1 ratio.

The Ni II atom in the title salt, [Ni(C 2 H 8 N 2 ) 3 ](C 10 H 6 O 6 S 2 ), is chelated by three ethylenediamine ligands in an octahedral geometry. The cation and anion are linked by N-HÁ Á ÁO hydrogen bonds into a three-dimensional network. One of the two -SO 3 groups is disordered over two positions in a 1:1 ratio.
Tris(ethylenediamine-2 N,N')nickel(II) naphthalene-2,7-disulfonate S. Gao and S. W. Ng Comment A previous study reported the crystal structure of tris(ethylenediamine)nickel(II) 2,6-naphthalenedisulfonate, which exists as a monohydrated salt (Huo et al., 2004). The present 2,7-napthalenedisulfonate is an anhydrous salt (Scheme I). The Ni II atom in Ni(en) 3 ] 2+ (C 10 H 6 O 6 S 2 ) 2is chelated by the en ligands in an octahedral geometry (Fig. 1). The cation and anion are linked by N-H···O hydrogen bonds into a hydrogen-bonded three-dimensional network ( Table 1). One of the two -SO 3 groups is disordered over two positions in a 1:1 ratio.

Experimental
Nickel nitrate (1 mmol) and sodium 2,7-naphthalenedisulfonate (1 mmol) were dissolved in water (10 mol); the pH was adjusted to ca 6 by the dropwise addition of ethylenediamine. The solution was filtered; the solvent was allowed to evaporate for several days. Red crystals were isolated from the filtrate after several days.

Refinement
C-bound H-atoms were generated geometrically and were included in the riding model approximation [C-H 0.93-0.97 Å, U 1.2U eq (C)]. The amino H atoms were located in a difference Fourier map, and were refined with a distance restraint of N-H 0.88±0.01 Å; their temperature factors were refined.
One sulfonate -SO 3 group is disordered over two positions in respect of the O atoms. Each pair of S-O/S-O' distances were restrained to within 0.01 Å of each other, and the temperature factors of the primed atoms were set to those of the unprimed ones. The anisotropic temperature factors of the disordered atoms were restrained to be nearly isotropic. The occupancy could not be refined, and the disorder was assumed to be a 1:1 type of disorder. Fig. 1. A displacement ellipsoid plot of [Ni(en) 3 ] (C 10 H 6 O 6 S 2 ) at the 50% probability level; hydrogen atoms are drawn as spheres of arbitrary radius; the disorder in the -SO 3 is not shown.