Di-μ-adipato-κ4 O 1:O 6-bis{aqua[5,6-diphenyl-3-(pyridin-2-yl)-1,2,4-triazine-κ2 N 2,N 3]copper(II)}

In the centrosymmetric binuclear title complex, [Cu2(C6H8O4)2(C20H14N4)2(H2O)2] or [Cu2(PDPT)2(C6H8O4)2(H2O)2] (PDPT = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, the Cu atom displays a distorted square-pyramidal coordination environment with the basal plane occupied by two PDPT N atoms and two O atoms from different adipate dianions while a water molecule is located at the apical position. Of the two water H atoms, one participates in an intramolecular hydrogen bond whereas the second participates in an intermolecular hydrogen bond, which leads to the formation of a chain along [010].

In the centrosymmetric binuclear title complex, [Cu 2 (C 6 H 8 O 4 ) 2 (C 20 H 14 N 4 ) 2 (H 2 O) 2 ] or [Cu 2 (PDPT) 2 -(C 6 H 8 O 4 ) 2 (H 2 O) 2 ] (PDPT = 3-(2-pyridyl)-5,6-diphenyl-1,2,4triazine, the Cu atom displays a distorted square-pyramidal coordination environment with the basal plane occupied by two PDPT N atoms and two O atoms from different adipate dianions while a water molecule is located at the apical position. Of the two water H atoms, one participates in an intramolecular hydrogen bond whereas the second participates in an intermolecular hydrogen bond, which leads to the formation of a chain along [010].

Wei Xu and Jin-Li Qi Comment
Research on coordination chemistry of triazine-derived ligands has progressed very rapidly during the past two decades (Kawamichi et al., 2009). The 1,2,4-triazine compounds are well-known in natural materials and show intersting biological, pharmacological and medicinal properties (Garcia et al., 1995). The 3-(2-pyridyl)-5,6-diphenyl-1,2,4triazine (PDPT) represents a principal class of N-donor heterocyclic ligands that exhibit interesting pharmacological properties such as blood platelet aggregation inhibition, significant activity towards leukemia and ovarian cancer, and anti-HIV activity (Mashaly et al., 1999;Soudi et al., 2005). It also has been widely used as an sensitive reagent for the determination of Fe(II) by spectrophotometric methods, in natural and waste water (Croot & Hunter, 2000). The title complex, was recently prepared and its crystal structure is reported here. . Through the adipato ligands, the square-pyramidally coordinated Cu atoms are linked to form centrosymmetric dinuclear. As expected, the Cu atom is slightly shifted toward the apical water O atom by 0.026 (2)Å from the least-squares plane defined by the four equatorial coordinating atoms. The triazine ring adopts a slight twist conformation. The dihedral angle between the two phenyl rings is 61.9 (2)°.

Experimental
Addition of 2.0 mL (1.0 M) NaOH to a stirred aqueous of 0.172 g (1.0 mmol) CuCl 2 . 2H 2 O in 5.0 mL H 2 O yield a blue precipitate, which was then separated by centrifugation, followed by washing with double-distilled water until no detectable Clanions in supernatant. The precipitate was added to a stirred ethanolic aqueous solution of 0.146 g (1.0 mmol) adipic acid in 20 mL EtOH/H 2 O (v:v = 1: 1). To the resulting suspension was added 0.310 g (1.0 mmol) 3-(2pyridyl)-5,6-diphenyl-1,2,4-triazine (PDPT). The mixture was further stirred for approximately 15 min and the insoluble solid was filtered off. The filtrate (pH = 6.5) was allowed to stand at room temperature. Slow evaporation for two weeks afforded a small amount of brown crystals (yield 58% based on the initial CuCl 2 . 2H 2 O input).

Refinement
All H atoms bound to C were position geometrically and refined as riding, with C-H = 0.93Å and 0.97Å with U iso (H) = 1.2U eq (C). The H atoms attached to O were located in difference Fourier maps and refined freely with U iso (H) = 1.5U eq (O).

Figure 1
The binuclear structure of title compound with the atom numbering scheme. Displacement ellipsoids are drawn at 40% probability level. H atoms are presented as a small spheres of arbitrary radius. Symmetry code: (i) -x, -y, -z+1.Di-µadipato-κ 4 O 1 :O 5 -bis{aqua[5,6-diphenyl-3-(pyridin-2-yl)-1,2,4-triazine-κ 2 N 2 ,N 3 ]copper(II)} Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.