catena-Poly[[tris(pyridine-κN)copper(II)]-μ-tetrafluoroterephthalato-κ2 O 1:O 4]

In the title compound, [Cu(C8F4O4)(C5H5N)3]n, the CuII atom, lying on a twofold rotation axis, is five-coordinated by two O atoms from two tetrafluoroterephthalate ligands and three N atoms from three pyridine ligands in a distorted trigonal-bipyramidal geometry. Adjacent CuII atoms are connected via the bridging tetrafluoroterephthalate ligands into a one-dimensional chain running along the [101] direction.

In the title compound, [Cu(C 8 F 4 O 4 )(C 5 H 5 N) 3 ] n , the Cu II atom, lying on a twofold rotation axis, is five-coordinated by two O atoms from two tetrafluoroterephthalate ligands and three N atoms from three pyridine ligands in a distorted trigonalbipyramidal geometry. Adjacent Cu II atoms are connected via the bridging tetrafluoroterephthalate ligands into a onedimensional chain running along the [101] direction.

Experimental
Crystal data [Cu(C 8  Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.  Recently, organically directed metal-terephthalates have attracted much attention due to their novel structures and desirable physical properties, and a lot of research work has been done on this type of complexes (Bastin et al., 2008;Eddaoudi et al., 2000;Gould et al., 2008). However, there are rare reports about halogen substituted terephthalate metal complexes till now. Some research work in computational study suggests that adsorption property in gas storage can be improved with electronegative atoms (e.g. halogen atoms) in the organic linkers or frameworks (Zhang et al., 2007). New topologies with favorable properties will be achieved by introducing some strong electronegative atoms to the phenyl ring.

Structure Reports Online
The title compound consists of one-dimensional neutral zig-zag chains ( Fig. 1 and Fig. 2). The tetrafluoroterephthalate ligand is coordinated to Cu II ion in a bridging bis-monodentate fashion. In the trigonal bipyramidal coordination unit, two O atoms from two tetrafluoroterephthalate ligands and one N atom from a pyridine molecule form the equatorial plane. The axial positions are occupied by N atoms from two pyridine molecules with an N-Cu-N angle of 174.71 (9)° ( Table 1).
The Cu-N bond lengths lie in the range of 2.0236 (16) to 2.073 (2) Å and agree well with the reported values (Baruah et al., 2007;Cheng et al., 2007). The Cu-O bond lengths are 2.0609 (12) Å, which are comparable with the reported values in the similar complexes (Baeg & Lee, 2003;Stephenson & Hardie, 2006;Yuan et al., 2004). In the aromatic ring systems, the values of bond lengths and angles coincide with those previously reported (Zheng et al., 2008).

Experimental
All the reagents and solvents employed were commercially available. Tetrafluoroterephthalic acid was purified by recrystallization. According to the literature procedure (Reineke et al., 1999), the title compound was synthesized by slow vapor diffusion at room temperature of pyridine (3 ml) into an N,N-dimethylformamide solution (2 ml) containing a mixture of tetrafluoroterephthalic acid (0.071 g, 0.30 mmol) and Cu(NO 3 ) 2 .3H 2 O (0.036 g, 0.15 mmol) diluted with CH 3 OH (6 ml). After two weeks, blue block-shaped crystals were obtained (yield 55% based on Cu

Refinement
H atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C).