catena-Poly[[tetra-μ-benzoato-κ8 O:O′-dicopper(II)]-μ-[N-(pyridin-4-yl)nicotinamide]-κ2 N:N′-[dibenzoato-κ2 O-copper(II)]-μ-[N-(pyridin-4-yl)nicotinamide]-κ2 N:N′]

In the polymeric title compound, [Cu3(C7H5O2)6(C11H9N3O)2]n, square-planar-coordinated CuII ions on crystallographic inversion centres are bound by two monodentate benzoate anions. The resulting [Cu(benzoate)]2 fragments are joined to centrosymmetic [Cu2(benzoate)4] paddlewheel clusters [Cu⋯Cu = 2.6331 (5) Å] by means of bridging N-(pyridin-4-yl)nicotinamide (4-pna) ligands [dihedral angle between the aromatic rings = 39.18 (12)°], thereby forming [Cu3(benzoate)6(4-pna)2]n coordination-polymer chains that are arranged parallel to the [30-1] crystal direction. These polymeric chains are anchored into supramolecular layers by N—H⋯O hydrogen bonding between neighboring 4-pna ligands. These layers aggregate by crystal packing forces to afford the crystal structure of the title compound.


Table 2
Hydrogen-bond geometry (Å , ). Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Crystal crystallographic inversion centre, a 4-pna ligand, and three benzoate ligands. Cu1 is square planar coordinated by trans 4pyridyl N atom donors from two 4-pna ligands and trans O atom donors from monodentate carboxylate groups belonging to two benzoate ligands. The other copper atom (Cu2) is square pyramidally coordinated, with its apical position occupied by a N atom donor from the nicotinamide end of a 4-pna ligand and its basal positions filled by O atom donors from four benzoate ligands.
Each individual chain is anchored to two others via N-H···O hydrogen bonding (Table 1) between amide moieties of neighboring 4-pna ligands. In this manner, supramolecular two-dimensional layers are constructed (Fig. 3); these lie parallel to the ac crystal planes. The three-dimensional structure of the title compound results from crystal packing forces between these layers, which stack along the b crystal direction. (Fig. 4).

Refinement
All H atoms bound to C atoms were placed in calculated positions, with C-H = 0.95 Å, and refined in riding mode with U iso = 1.2U eq (C). The H atom within the amide group of the 4-pna ligand was found in a difference Fourier map, restrained with N-H = 0.9 Å and refined with U iso = 1.2U eq (N).

Figure 1
The asymmetric unit of the title compound, showing 50% probability ellipsoids, complete coordination environments, and atom numbering scheme. Hydrogen atom positions are shown as grey sticks with the exception of the amide group hydrogen atom. Color codes: dark blue Cu, red O, light blue N, black C, pink H. Symmetry codes: (i) -x, -y + 1, -z; (ii) -x + 3, -y + 1, -z -1.

copper(II)]-µ-[N-(pyridin-4-yl)nicotinamide]-κ 2 N:N′]
Crystal data [Cu 3 (C 7 H 5 O 2 ) 6 (C 11 H 9 N 3 O) 2 ] M r = 1315.70 Triclinic, P1 Hall symbol: -P 1 a = 8.9183 (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.