Tris(2,2′-bipyridyl-κ2 N,N′)copper(II) sulfate 7.5-hydrate

The title compound, [Cu(C10H8N2)3]SO4·7.5H2O, is a six-coordinate copper(II) complex with a slightly elongated octahedral coordination geometry. The pyridyl rings of the three bipyridyl ligands are not coplanar, making dihedral angels of 9.5 (5), 5.2 (4) and 5.8 (5)°. In the crystal, several O—H⋯O and C—H⋯O hydrogen-bonding interactions are observed due to the existance of a large number of water molecules and the sulfate dianions.

The title compound, [Cu(C 10 H 8 N 2 ) 3 ]SO 4 Á7.5H 2 O, is a sixcoordinate copper(II) complex with a slightly elongated octahedral coordination geometry. The pyridyl rings of the three bipyridyl ligands are not coplanar, making dihedral angels of 9.5 (5), 5.2 (4) and 5.8 (5) . In the crystal, several O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen-bonding interactions are observed due to the existance of a large number of water molecules and the sulfate dianions.
The atom-numbering scheme of compound (I) is shown in Fig. 1, while selected bond distances and angles are given in Table 1. The coordination geometry of the complex about the six-coordinate Cu(II) center is slightly elongated octahedral.
Four shorter Cu-N bonds occupy the equatorial plane, with a mean bond length of 2.083 (4) Å, while two axial Cu-N bonds are a little longer [Cu1-N3 = 2.173 (4) Å and Cu1-N6 = 2.176 (4) Å]. The pyridyl rings of three bipyridyl ligands are not coplanar with the dihedral angels of 9.5 (5)°, 5.2 (4)° and 5.8 (5)°, respectively. In the crystal packing of (I), quite a few O-H···O and C-H···O hydrogen bonding interactions are observed due to the existance of a large number of water molecules and the sulfate dianions.

Experimental
The title compound was obtained from a mixed methanol/water solution of NaCl and Cu(NO 3 ) 2 .3H 2 O by slow evaporation in air at room temperature.
Single crystals of compound (I) suitable for X-ray diffraction determination were formed from the filtrate as a by-product when CuSO 4 .5H 2 O (1.248 g, 5 mmol) was reacted with 2,2'-bipyridine (1.562 g, 10 mmol) in methanol (100 ml

Refinement
The non-hydrogen atoms were refined anisotropically, whereas the H atoms were placed in geometrically idealized positions (C-H = 0.93 Å and O-H = 0.82-0.96 Å) and refined as riding atoms, with U iso (H) = 1.2 eq (C) and U iso (H) = 1.5U eq (O).
supplementary materials sup-2 Figures Fig. 1. An ORTEP drawing of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Data collection
Bruker SMART APEX CCD area-detector diffractometer 6101 independent reflections

Special details
Experimental. The structure was solved by direct methods (Bruker, 2000) and successive difference Fourier syntheses. 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.