(Benzoato-κO)bis(1,10-phenanthroline-κ2 N,N′)copper(II) chloride benzoic acid disolvate

In the title complex, [Cu(C7H5O2)(C12H8N2)2]Cl·2C6H5COOH, the CuII ion is coordinated by one carboxylate O atom from a benzoate anion and four N atoms from two phenantroline ligands in a distorted five-coordinate trigonal-bipyramidal CuON4 chromophore. The Cu2+ and the Cl− ion are imposed by a twofold rotation axiss which also bisects the equally disordered benzoate anion. In the crystal, the molecules are assembled into chains along [010] by C—H⋯Cl, O—H⋯Cl and C—H⋯O hydrogen-bonding interactions. The resulting chains are further connected into two-dimensional supramolecular layers parallel to [100] by interchain π⋯π stacking interactions [centroid–centroid distance = 3.823 (5) Å] between the phenanthroline ligands and the benzoic acid molecules, and by C—H⋯O hydrogen-bonding interactions. Strong π⋯π stacking interactions between adjacent phenantroline ligands [3.548 (4) Å] assemble the layers into a three-dimensional supramolecular architecture.

In the title complex, [Cu(C 7 H 5 O 2 )(C 12 H 8 N 2 ) 2 ]ClÁ2C 6 H 5 -COOH, the Cu II ion is coordinated by one carboxylate O atom from a benzoate anion and four N atoms from two phenantroline ligands in a distorted five-coordinate trigonalbipyramidal CuON 4 chromophore. The Cu 2+ and the Cl À ion are imposed by a twofold rotation axiss which also bisects the equally disordered benzoate anion. In the crystal, the molecules are assembled into chains along [010] by C-HÁ Á ÁCl, O-HÁ Á ÁCl and C-HÁ Á ÁO hydrogen-bonding interactions. The resulting chains are further connected into twodimensional supramolecular layers parallel to [100] by interchain Á Á Á stacking interactions [centroid-centroid distance = 3.823 (5) Å ] between the phenanthroline ligands and the benzoic acid molecules, and by C-HÁ Á ÁO hydrogen-bonding interactions. Strong Á Á Á stacking interactions between adjacent phenantroline ligands [3.548 (4) Å ] assemble the layers into a three-dimensional supramolecular architecture.

Comment
Over the past decades, vast efforts have been dedicated to rational design and synthesis of copper-aromatic-acid coordination polymers, due to their potential applications in medicine, electronics, magnetism, catalysis, gas storage, etc··· It is well known that aromatic carboxylic acids, such as p-phthalic acid (Li et al., 2006) and salicylic acid (Devereux et al., 2007), were used to construct coordination polymers with copper salts and exhibited interesting electrochemical properties. In the present contribution, we report a new copper coordination complex, [Cu(phen) 2 (C 6 H 5 COO)].2(C 6 H 5 COOH).Cl, resulting from self-assembly of Cu II ions, phenanthroline ligands and benzoic acid molecules.
The crystal structure of the title complex consists of [Cu(phen) 2 (C 6 H 5 COO)] + cations, free benzoic acid molecules and uncoordinated Clanions in a ratio 1:2:1. The Cu II ion is coordinated by one carboxylate O atom from a benzoate anion and four N atoms from two phenantroline ligands to complete a distorted five-coordinate trigonal bipyramidal CuON 4 chromophore. The equatorial positions of the Cu II ion are occupied by one O atom and two N atoms from different phen molecules, and the axial ones by the other two N atoms. The Addison's τ value of 0.53 (τ = 0 for an ideal square pyramid and τ = 1 for an ideal trigonal bipyramid) speaks for a trigonal bipyramid character with a '3+2' coordination type (Addison et al., 1984), which is similar to that of Cu atom in the literature (Mao et al., 2001). The dihedral angle between the benzene ring plane and the carboxylate plane of the coordinated benzoic ion is 14.4 (1)°, which is larger than the dihedral angle in the free benzoic acid molecule (6.5 (6)°). In addition, the Cu II ions and the benzoate ligands are crystallographically imposed by 2-fold rotation axes. The molecules are assembled into one-dimensional chains along [010] direction through hydrogen bonds interactions (C5-H5A···Cl, O3-H3A···Cl, C24-H24A···O4, C8-H8A···O3). The resulting chains are further connected into two-dimensional supramolecular layers parallel to [100] by interchain π···π stacking interactions (3.823 (5) Å) between the phenantroline ligands and the molecular benzoic acid, and by hydrogen bonding interactions (C10-H10A···O1, C12-H12A···O1). Furthermore, on the basis of strong π···π stacking interactions between interlayer adjacent phenantroline ligands (3.548 (4) Å), the layers are assembled into a three-dimensional supramolecular architecture.

Experimental
Dropwise addition of 2.0 mL (1.0 M) NaOH to a stirred aqueous solution of 0.1708 g (1.001 mmol) CuCl 2 .H 2 O in 10.0 mL H 2 O afforded a blue precipitate, which was separated by centrifugation and washed with distilled water for 5 times. The gathered precipitate was then transferred into a solution of benzoic acid (0.2448 g, 2.0049 mmol) and 1,10-phenanthroline (0.1986 g, 1.002 mmol) in a mixed solvent composed of 10.0 mL H 2 O and 10.0 mL ethanol to yield a blue suspension. The mixture was then stirred for further 30 min. After filtration, the filtrate was kept at room temperature and afforded a small amount of blue crystalline blocks after 20 days.
supplementary materials sup-2 Refinement H atoms bonded to C atoms were placed in geometrically calculated positions and were refined using a riding model, with U iso (H) = 1.2 U eq (C). The H atom attached to O3 was found in a difference Fourier map and was refined using a riding model, with the O-H bond distance fixed as initially found and with U iso (H) value set at 1.2 U eq (O).

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 > σ(F 2 ) is used only for calculating Rfactors(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.