Aqua{2-(pyridin-2-yl)-N-[(pyridin-2-yl)methylidene]ethanamine-κ3 N,N′,N′′}(sulfato-κ2 O,O′)copper(II) tetrahydrate

The title complex, [Cu(SO4)(C13H13N3)(H2O)]·4H2O, was obtained by mixing copper sulfate pentahydrate and 2-(pyridin-2-yl)-N-(pyridin-2-ylmethylidene)ethanamine in ethanol under reflux conditions. The CuII ion shows a Jahn–Teller-distorted octahedral geometry, with equatorial positions occupied by three N atoms from the tridentate ligand (average Cu—N = 2.004 Å) and one O atom from a bidentate sulfate anion [Cu—O = 1.963 (2) Å]. The axial positions are occupied by one O atom from a coordinating water molecule [Cu—O = 2.230 (3) Å] and one weakly bonded O atom [Cu—O = 2.750 (2) Å] from the bidentate sulfate ion. The complex molecules are connected through O—H⋯O hydrogen bonds between the coordinating water molecules and sulfate ions from neighboring complexes, forming a double chain parallel to the c axis. The chains are stabilized through additional hydrogen bonds by one of the non-coordinating water molecules bridging between neighboring strands of the double chains. The remaining three water molecules fill the interstitial space between the double chains and are involved in an intricate hydrogen-bonding network that consolidates the structure.

The title complex, [Cu(SO 4 (2) Å ] from the bidentate sulfate ion. The complex molecules are connected through O-HÁ Á ÁO hydrogen bonds between the coordinating water molecules and sulfate ions from neighboring complexes, forming a double chain parallel to the c axis. The chains are stabilized through additional hydrogen bonds by one of the non-coordinating water molecules bridging between neighboring strands of the double chains. The remaining three water molecules fill the interstitial space between the double chains and are involved in an intricate hydrogen-bonding network that consolidates the structure.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZL2518). The axial positions are occupied by the oxygen atom of the coordinated water molecule and one O atom from the bidentate sulfate. The axial bond lengths between the Cu II ion and the O atoms are considerably longer than the equatorial bond distances between the Cu II ion and the O atom of the sulfate ligand as a consequence of the Jahn-Teller effect (Jahn & Teller, 1937).
The sulfate anion has a slightly distorted tetrahedral geometry due to the fact that two of the oxygen atoms of the sulfate group are coordinated to the metal center, with one of the Cu-O distances being considerably longer than the other one  (Table 1). The interstitial space between the double chains is filled by the three remaining lattice water molecules which are involved in an intricate hydrogen bonding network that consolidates the crystal packing.
The green solution was filtered off and left for slow evaporation. Crystals that separated from the green solution, were filtered off and recrystallized from dimethylformamide. On standing for two weeks, crystals suitable for X-ray diffraction analysis were obtained. Yield: 74.5%. Anal. Calc. for [C 13 H 23

Refinement
H atoms of the water molecule were located in the Fourier difference maps and refined with O-H distance restraints of 0.82 (2) Å. Additional H···O distance restraints were used for H atoms of two water molecules (O8W and O9W). H atoms of =CH and CH 2 groups were placed geometrically and refined using a riding model with C-H distantces between 0.93 and 0.97 Å with U iso (H) = 1.2U eq (C).

Figure 3
View of the structure along the c axis.

Aqua{2-(pyridin-2-yl)-N-[(pyridin-2-yl)methylidene]ethanamine-κ 3 N,N′,N′′}(sulfato-κ 2 O,O′)copper(II)
tetrahydrate 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 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.