Bis(1,10-phenanthroline-κ2 N,N′)(phenylacetato-κO)copper(II) phenylacetate hexahydrate

In the title compound, [Cu(C8H7O2)(C12H8N2)2](C8H7O2)·6H2O, the Cu atom is in a distorted square-pyramidal coordination environment. The six crystallographically independent uncoordinated water molecules are interconnected by hydrogen bonds, completing dodecawater (H2O)12 clusters which are hydrogen bonded to the carboxylate groups of phenylacetate anions, building up one-dimensional anionic chains propagating along [100]. Between the cationic and anionic chains are hydrogen bonds from water molecules to the carboxylate O atoms belonging to the phenylacetato ligands.


Experimental
Crystal data [Cu(C 8 H 7 O 2 ) (C 12  Construction of supramolecular architectures with interesting physical properties has grown rapidly owing to their potential use as new functional materials (Lehn, 2007). The most efficient and widely used approach for designing such materials is the self-assembly of organic ligands and metal ions (Kuroda-Sowa et al., 1997;Li et al., 2008). Here, we report a Cu(II) complex [Cu(C 12 H 8 N 2 ) 2 (C 8 H 7 O 2 )](C 8 H 7 O 2 ).6H 2 O from the self-assembly of Cu(OH) 2 , phenylacetatic acid and phenanthroline.
The title compound consists of [Cu (C 12  previously reported by us (Zheng et al., 2001) and all the bonding parameters are normal (Baruah et al., 2007). As far as the phenylacetato ligand is concerned, the phenyl plane is found to be nearly perpendicular to the single bonded carbon backbone (dihedral angle: 89.5 (1)°), which is significantly larger than the corresponding one of 68.6 (2)° in the non-coordinating phenylacetate anion, and the carboxylate group is twisted from the single bonded carbon backbone by 70.4 (2)° in the former coordinating one, and is considerably larger the 60.7 (2)° in the non-coordinating anion. As expected, the C-O bond distance for the coordinating oxygen atom is 1.281 (2) Å, which is longer than those for non-coordinating ones (1.247-1.254 Å).
The complex cations are distributed in such a way that the symmetry-related phenanthroline ligands are oriented antiparallel with a mean interplanar distance of 3.39 (2) Å, indicating a significant face-to-face π-π stacking interaction (Sugimori et al., 1997). Owing to such intercationic π-π stacking interactions and weak intercationic C-H···O interactions with the uncoordinating carboxylate oxygen atom, two centrosymmetrically related complex cations form dimers, which are further assembled via interdimeric π-π stacking interactions into 1D chains extending along the [101] direction. Furthermore, the resulting chains are arranged in planes parallel to (010), between which the lattice water molecules and the phenylacetate anions are sandwiched.
Out of the six crystallographically distinct lattice water molecules, three water molecules together with their centrosymmetry-related partners are hydrogen bonded to one another to generate chair-like hexawater clusters (Fig.2) gave a blue precipitate, which was separated by centrifugation and washed with water until no Cl anions were detectable in the supernatant. The collected blue precipitate was transferred to a mixture of ethanol and water (1:1 V/V, 10 mL), to which phenanthroline (0.198 g, 1.00 mmol) and phenylacetic acid (0.136 g, 1.00 mmol) were added successively. The resulting blue solution (pH = 7.52) was allowed to stand at room temperature. Blue blocklike crystals were grown by slow evaporation for over 7 days.

Refinement
All H atoms bound to C were positioned geometrically and refined as riding, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C).
Hydrogen atoms attached to O were located in a difference Fourier map and refined isotropically, with the O-H distances restrained to 0.85 (1) Å and with U iso (H) = 1.2U eq (O). Fig. 1

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.
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 > 2sigma(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.  (7 (7) (2) 161.44 Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x−1, y+1, z; (iii) −x+2, −y, −z+1; (iv) −x+1, −y+1, −z+1; (v) x, y−1, z.