Aquachlorido(3,5-dinitro-2-oxidobenzoato-κ2 O 1,O 2)(1,10-phenanthroline-κ2 N,N′)chromium(III)

In the title compound, [Cr(C7H2N2O7)Cl(C12H8N2)(H2O)], the CrIII atom displays a distorted octahedral coordination geometry, with the chelating phenantroline and 3,5-dinitrosalicylate ligands in trans positions. In the crystal, molecules are connected via O—H⋯O hydrogen bonds into a two-dimensional framework parallel to (100). In addition, there are π–π stacking interactions between phenanthroline ligands along the c axis, with a mean interplanar distance of 3.456 (4) Å.

In the title compound, [Cr(C 7 H 2 N 2 O 7 )Cl(C 12 H 8 N 2 )(H 2 O)], the Cr III atom displays a distorted octahedral coordination geometry, with the chelating phenantroline and 3,5-dinitrosalicylate ligands in trans positions. In the crystal, molecules are connected via O-HÁ Á ÁO hydrogen bonds into a twodimensional framework parallel to (100). In addition, there arestacking interactions between phenanthroline ligands along the c axis, with a mean interplanar distance of 3.456 (4) Å .

Related literature
For the structure of a similar Mn III complex, see: Tan & Tang (1996). For -stacking interactions in metal complexes, see: Janiak (2000).
Data collection: APEX2 (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. chromium atom is octahedrally coordinated by two N atoms from the phenanthroline ligand, two O atoms from the (C 7 H 2 N 2 O 7 ) 2anion, one Cl ion and one water molecule. Bond lengths to the metal center are given in Table 1. The molecules are connected via O-H···O hydrogen bonds resulting in the formation of a two-dimensional supermolecular structure (Fig. 2). Moreover, there are π -π stacking interactions between phenanthroline ligands along the c axis due to the fact that these aromatic groups of phenanthroline ligands are parallel with each other. Such π -π stacking interactions between aromatic groups are rather popular in coordination compounds. Hydrogen bonds and π -π stacking interactions play a crucial role in stability of the crystal structure.

Experimental
All chemicals were of reagent grade quality obtained from commercial sources and used without further purification. The title compound was synthesized from a mixture of CrCl 3 .6H 2 O (0.80 g, 3 mmol), 3,5-dinitrosalicylic acid (0.68 g, 3 mmol) and 1, 10-phenanthroline (0.60 g, 3 mmol), NaOH (0.08 g, 2 mmol) and ethanol (20 mL) by hydrothermal reaction. The mixture was stirred for half an hour, and then transferred into a Teflon-lined stainless steel autoclave (50 mL) and treated at 160 °C for 3 days. After the mixture was slowly cooled to room temperature, green block crystals suitable for X-ray structure determination were obtained.

Refinement
The H atoms bonded to C were positioned geometrically and refined using a riding model, with C-H = 0.93 Å and with U iso (H) = 1.2 times U eq (C). The H atoms bonded to O atoms were located from Fourier difference maps and refined with distance restraints of O8-H1WA = 0.83 (2) Å, and O8-H1WB = 0.83 (2) Å.  View of the title molecule with displacement ellipsoids drawn at the 30% probability level.

Figure 2
Crystal packing along the c axis. Hydrogen bonds are shown as dashed lines.

Aquachlorido(3,5-dinitro-2-oxidobenzoato-κ 2 O 1 ,O 2 )(1,10-phenanthroline-κ 2 N,N′)chromium(III)
Crystal data [Cr(C 7  Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq