catena-Poly[[silver(I)-μ-4,4′-bipyridine-κ2 N:N′] 4-[2-(4-carboxyphenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]benzoate]

Assembly of the flexible dicarboxylic ligand 4-[2-(4-carboxyphenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]benzoate and 4,4′-bipyridine as co-ligand with AgI ions resulted in the formation of the polymeric title compound, {[Ag(C10H8N2)](C17H9F6O4)}n, in which the metal atoms are bridged by the 4,4′-bipyridine ligands, generating cationic chains extending along [010]. The dihedral angles between the benzene rings in the anion and the pyridine rings in the cation are 72.42 (9) and 9.36 (10)°, respectively. The molecular conformation of the anion is stabilized by intramolecular C—H⋯F hydrogen bonds. In the crystal, the anions interact with the cationic chains via C—H⋯O hydrogen bonds, forming layers parallel to (001), in which weak π–π stacking interactions [centroid–centroid distances = 3.975 (3)–4.047 (3) Å] involving the pyridine rings of adjacent 4,4′-bipyridine ligands are present. The planes are further assembled into a three-dimensional network by O—H⋯O hydrogen bonds.

Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. dicarboxylate tectons, the conformational freedom nature of the flexible polycarboxyl modules may provide more possibility for the construction of unusual coordination frameworks compared with rigid ligands (Liu et al., 2011). 4,4′-(Hexafluoroisopropylidene)bis(benzoic acid) (H 2 L) as a V-shaped flexible dicarboxyl ligand has been investigated for its bent geometry, which can induce novel topological motifs and potential functional materials (Jiang et al., 2009;Ji et al., 2010). Herein the synthesis and structure of a new crystalline complex is reported, generated from the incorporation of the V-shaped dicarboxyl spacer H 2 L with 4,4′-bipyridine (bipy) as co-ligand and Ag I ion, which displays a one-dimensional polymeric chain motif.
The asymmetric unit of the title compound consists of one silver(I) cation, one bipy molecule and one HL anion ( Fig.   1). Each metal atom is coordinated in a nearly linear geometry (N2-Ag1-N1 i = 171.36 (9)°; symmetry code: (i) x, -1+y, z) by a pair of nitrogen donors from two bipy molecules, forming one-dimensional polymeric chain motifs along the [010] direction with Ag···Ag separations of 11.436 (5) Å. If the Ag···O separations with the monoprotonated carboxylate anion are considered (Ag1···O2, 2.680 (2) Å; Ag1···O1, 2.701 (2) Å), the HL ligands can be seen as pendants of the Ag-bipy chains. In the cation, the dihedral angle formed by the pyridine rings is 72.42 (9)°, while the dihedral angle formed by the benzene rings in the anion is 9.36 (10)°. The molecular conformation of the anion is enforced by intramolecular C-H···F hydrogen bonds (Table 1). In the crystal packing, anions and cationic chains interact through C -H···O hydrogen bonds to generate layers parallel to the ab plane. In each layer, weak π-π stacking interactions

Experimental
A mixture of H 2 L (20.2 mg, 0.05 mmol), silver acetate (16.8 mg, 0.10 mmol), 4,4′-bipyridine (15.4 mg, 0.10 mmol) and water (10 ml) was sealed in a Teflon-lined stainless steel vessel (20 ml), which was heated at 433°C for three days and then cooled to room temperature. Colourless needle-like crystals of title compound were obtained in 61% yield (20.0 mg, based on H 2 L).

Refinement
The carbonyl H atom was first located in a difference Fourier map and then refined with O-H = 0.82 Å, and with U iso (H) = 1.5U eq (O). The C-bound H atoms were placed at calculated positions and refined as riding with C-H = 0.93 Å, and with U iso (H) = 1.2U eq (C).

Figure 1
The asymmetric unit of title compound with 30% probability displacement ellipsoids [symmetry codes: (i) x, -1+y, z; (ii) = x, 1+y,z).  View of the 3-D supramolecular organization of the title compound constructed from π-π stacking interactions (green dotted lines) and hydrogen bonds (dotted lines). Overlapping layers parallel to the ab plane are coloured in blue and magenta.

Crystal data
[Ag(C 10 H 8 N 2 )](C 17 H 9 F 6 O 4 ) M r = 655.30 Monoclinic, P2 1 /c Hall symbol: -P 2ybc a = 16.434 (7) Å b = 11.436 (5) Å c = 14.320 (6) Å β = 104.310 (7) 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq