Bis(propane-1,3-diamine)disaccharinatonickel(II)

In the title complex, [Ni(C7H4NO3S)2(C3H10N2)2] or [Ni(sac)2(pen)2] (sac = saccharinate or 1,1,3-trioxo-2,3-dihydro-1λ6,2-benzothiazol-2-ide and pen = propane-1,3-diamine), the NiII ion sits on an inversion center, being coordinated by two N atoms of the sac ligands, which occupy trans positions, and four N atoms of the bidentate pen ligands to define a distorted octahedral geometry. The pen ligands chelate the metal ion, forming a six-membered ring which adopts a half-chair conformation, while the sac ligands adopt the most common coordination mode. The crystal packing is stabilized by N—H⋯O hydrogen bonds, which form a one-dimensional network along [010]. It is also supported by an N—H⋯S hydrogen bond between the amine group of the pen ligand and the sulfonyl group of the sac ligand.

In the title complex, [Ni(C 7 H 4 NO 3 S) 2 (C 3 H 10 N 2 ) 2 ] or [Ni(sac) 2 (pen) 2 ] (sac = saccharinate or 1,1,3-trioxo-2,3dihydro-1 6,2 -benzothiazol-2-ide and pen = propane-1,3diamine), the Ni II ion sits on an inversion center, being coordinated by two N atoms of the sac ligands, which occupy trans positions, and four N atoms of the bidentate pen ligands to define a distorted octahedral geometry. The pen ligands chelate the metal ion, forming a six-membered ring which adopts a half-chair conformation, while the sac ligands adopt the most common coordination mode. The crystal packing is stabilized by N-HÁ Á ÁO hydrogen bonds, which form a onedimensional network along [010]. It is also supported by an N-HÁ Á ÁS hydrogen bond between the amine group of the pen ligand and the sulfonyl group of the sac ligand.
Because of the biological significance of saccharin, there has been increased interest in its metal complexes, especially with first-row transition metals (Paşaoğlu et al., 2007;Heren et al., 2008. Saccharin, or its anion, may bond to metals by means of their imino nitrogen, carbonyl oxygen, or sulfonyl oxygen atoms. In the last two decades, the metal saccharinates and metal complexes including saccharin and various N-donor ligands (mono-or bidentate) have been intensively studied by many investigators. In the present study, the mixed-ligand Ni II complex of saccharinate with pen (Scheme) is investigated.
In the title compound, Ni II ion sits on an inversion center, being coordinated by two N atoms of sac ligand and four N atoms of bidentate pen ligands in trans positions. The bond distances and angles (Table 1) show that the coordination polyhedron of the Ni II ion is a distorted octahedron. The equatorial plane of the octahedron is defined by the N atoms of pen ligands, whereas the axial positions are occupied by the N atoms of the sac ligands ( Fig. 1). It is seen that the pen ligands chelate the metal ion to form a six-membered ring adopting a half-chair conformation while sac ligands prefer the most common coordination mode. The intra-ligand bond lengths and angles of the sac ligand are similar to those observed in previous studies (Paşaoğlu et al., 2007;Heren et al., 2008). The sac ligand is planar, with an r.m.s deviation of 0.022 Å. The dihedral angle between the equatorial plane and the mean plane of sac was measured as 84.50 (7)°. It is seen in Table 1 that the Ni-N pen bond distances span the range 2.094 (3)-2.119 (3) Å, being shorter than Ni-Nsac distance (2.262 (2) Å) which is comparable to that observed in [Ni(C 7 H 4 NO 3 S)(C 5 H 9 N 3 ) 2 ] (2.2874 (19) Å) (Bulut et al., 2007). The crystal packing of the complex is mainly stabilized by hydrogen bonds of N-H···O type (Table 2). Multiple H-bond donor and acceptor behaviors of amine and sulfonyl groups enable a variety of chain and ring systems in the crystal packing. For example, the inter-molecular N2-H2B···O3 iii (iii: -x, -1 -y, 1 -z) hydrogen bonds form centrosymmetric R 2 2 (12) (Bernstein et al., 1995) rings located at (0, 1/2+n, 1/2: n=0 or integer) positions to form onedimensional hyrogen bonding network along [010] (Fig. 2). On the other hand, the same ring motifs are also formed by N3-H3B···O2 i (i:-x, -y, 1 -z) hydrogen bonds (Fig. 3).

Experimental
An aquous solution of pen (2.54 mmol, 0.19 g) was added dropwise with stirring to a solution of [Ni(sac) 2 (H 2 O) 4 ].2H 2 O (1.27 mmol, 1.00 g). The mixture was heated to 343 K in a temperature-controlled bath and stirred for 3 h. The green reaction mixture was filtered and left for crystallization in room temperature. After two weeks, the violet crystals of the title complex were selected for X-ray experiment. IR (KBr, ν cm -1 ), stretching vibrations: 3326-3290 (NH 2 ), 3153-3060

Refinement
All H atoms except those involved in H-bonds were positioned geometrically and treated using a riding model, with the distances of 0.970 and 0.930 Å for methylene and aromatic groups, respectively. The displacement parameters of the H atoms were constrained with U iso (H) = 1.2U eq for parent atoms.

Figure 3
The formation of centrosymmetric R 2 2 (12) rings. Benzene rings and some H atoms were omitted for clarity.

Crystal data
[Ni(C 7 H 4 NO 3 S) 2 (C 3 H 10 N 2 ) 2 ] M r = 571.31 Monoclinic, P2 1 /n Hall symbol: -P 2yn a = 11.447 (5)   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.74 e Å −3 Δρ min = −0.37 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0040 (12) 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.