Aquachlorido(2,2′:6′,2′′-terpyridyl)copper(II) chloride monohydrate

The title complex, [CuCl(C15H11N3)(H2O)]Cl·H2O, is composed of a monocation that possesses mirror symmetry. The CuII atom has a distorted square-pyramidal geometry, being coordinated by the three N atoms of the terpyridine ligand and a Cl atom in the equatorial plane, and by a water molecule O atom in the axial position. The charges are balanced by a chloride anion positionally disorded over two positions related by the mirror symmetry. The compound crystallizes as a monohydrate, with the water molecule also being positionally disordered over two positions related by the mirror symmetry. In the crystal, the various components of the complex are linked via O—H⋯O and O—H⋯Cl hydrogen bonds, forming a two-dimensional network in the ab plane. There are also a number of C—H⋯Cl and C—H⋯O interactions which stabilize the crystal structure.

The title complex, [CuCl(C 15 H 11 N 3 )(H 2 O)]ClÁH 2 O, is composed of a monocation that possesses mirror symmetry. The Cu II atom has a distorted square-pyramidal geometry, being coordinated by the three N atoms of the terpyridine ligand and a Cl atom in the equatorial plane, and by a water molecule O atom in the axial position. The charges are balanced by a chloride anion positionally disorded over two positions related by the mirror symmetry. The compound crystallizes as a monohydrate, with the water molecule also being positionally disordered over two positions related by the mirror symmetry. In the crystal, the various components of the complex are linked via O-HÁ Á ÁO and O-HÁ Á ÁCl hydrogen bonds, forming a two-dimensional network in the ab plane. There are also a number of C-HÁ Á ÁCl and C-HÁ Á ÁO interactions which stabilize the crystal structure.

Related literature
For details of the Cambridge Structural Database, see: Allen (2002). For the structure of a related compound, see: Koo et al. (2003). For the descriptor for 5-coordination, see: Addison et al. (1984); Spek (2009).
The structure of compound (I) is illustrated in Fig. 1. It is composed of a [(H 2 OClCu(terp)] + cation that possesses mirror symmetry (with atoms Cu1, Cl1, N1, O1W and C3 lying in the mirror plane), and a Clanion. This anion, atom Cl2, is positionally disordered over two postions related by the mirror symmetry. A water molecule of crystallization, O2W, is also present and it too is positionally disordered over two postions related by the mirror symmetry. The bond distances and angles are similar to those in compound (II). For example, the Cu1-Cl1 and Cu1-O1W distances are 2.2255 (6) and 2.3372(19 Å, respectively, compared to 2.233 and 2.330 Å, respectively, in (II). The copper coordination sphere is distorted square pyramidal with a τ value of 0.17, compared to 0.18 in (II) [idealized values are 0 for square pyramidal and 1 for trigonal bipyramidal; Addison et al., 1984;Spek, 2009].
In the crystal of (I) the cations are linked to the anions and the water molecules of crystallization by O-H···O and O-H···Cl hydrogen bonds resulting in the formation of a two-dimensional network (Table 1 and Fig. 2). In the crystal C-H···O and C-H···Cl interactions are also present (Table 1).

Experimental
An aqueous solution (20 ml) of copper(II)chloride dihydrate (0.429 mmol, 75 mg) and 2, 2':6' 2''-terpyridine (0.429 mmol, 100 mg) was heated at 353 K for 1 h. After hot filtration the green solution was cooled to RT and sodium sulfite (1.717 mmol, 216 mg) was added. The resulting solution was left in the fridge for two months and green block-like crystals were obtained together with a small quantity of greenish-blue crystals. The latter were shown by X-ray diffraction analysis to be the title compound (I).

Refinement
The chlorine anion (Cl2) and the water molecule of crystallization (O2W) were found to be split over two positions related by the mirror plane; they were refined with occupancies of 0.5 each. The water molecule H-atoms were located in a difference electron-density map and were refined with distance restraints of 0.84 (2) Å and U iso (H) = 1.5U eq (O). The C-bound H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.95 Å with U iso (H) = 1.2U eq (C).   Table 1 for details; H-atoms not involved in hydrogen bonding have been omitted for clarity).

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles 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.