Bis(μ-N,N′-di-3-pyridylpyridine-2,6-dicarboxamide)bis[dichloridomercury(II)] N,N-dimethylformamide disolvate

The asymmetric unit of the binuclear title complex, [Hg2Cl4(C17H13N5O2)2]·2C3H7NO, contains one-half of the centrosymmetric molecule and one dimethylformamide solvent molecule. The HgII atom is four-coordinated by two N atoms from two ligands and two Cl atoms in a distorted tetrahedral coordination geometry. Intramolecular N—H⋯O hydrogen bonds may be effective in the stabilization of the structure. In the crystal structure, π–π contacts between pyridine rings [centroid-to-centroid distances 3.629 (3) and 3.595 (3) Å] may further stabilize the structure.

The asymmetric unit of the binuclear title complex, [Hg 2 Cl 4 -(C 17 H 13 N 5 O 2 ) 2 ]Á2C 3 H 7 NO, contains one-half of the centrosymmetric molecule and one dimethylformamide solvent molecule.The Hg II atom is four-coordinated by two N atoms from two ligands and two Cl atoms in a distorted tetrahedral coordination geometry.Intramolecular N-HÁ Á ÁO hydrogen bonds may be effective in the stabilization of the structure.In the crystal structure,contacts between pyridine rings [centroid-to-centroid distances 3.629 (3) and 3.595 (3) A ˚] may further stabilize the structure.

Experimental
Crystal data Table 2 Hydrogen-bond geometry (A ˚, ).supporting information Acta Cryst. (2009). E65, m15-m16 [doi:10.1107The expansion of the field of metal-organic frameworks (MOFs) of predetermined structure depends on the judicious choice of new linkers and nodes of appropriate coordination algorithms (Ockwig et al., 2005).Rigid polydentate N-donor ligands are typical linkers employed in such a work.N,N′-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide, with a rigid conjugated clamp-like configuration, is a convenient bridging ligand for the syntheses of cyclic complexes (Qin et al., 2003;Baer et al., 2002).In this work, we selected this ligand as linker, to generate the new title coordination complex, and we report herein its crystal structure.
The asymmetric unit of the title compound (Fig. 1) contains one-half molecule and an N,N-dimethylformamide (DMF) molecule, where the bond lengths (Allen et al., 1987) and angles are within normal ranges.The Hg II atom is fourcoordinated by two N atoms from two ligands and two Cl atoms in a distorted tetrahedral coordination geometry (Table 1).The two Hg II atoms are bridged with two N, N′-bis(pyridin-3-yl) 2, Fig. 1) may be effective in the stabilization of the structure.

S2. Experimental
For the preparation of the title compound, the ligand N,N′-bis-(pyridin-3-yl)-2,6-pyridinedicarboxamide (0.016 g, 0.05 mmol) in DMF (5 ml) was added dropwise to a solution of HgCl2 (0.028 g, 0.1 mmol) in methanol (5 ml).The precipitate was filtered and the resulting solution was allowed to stand at room temperature in the dark.After one week high quality colorless crystals were obtained and dried in air.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.

Figure 1
Figure 1The asymmetric unit of the title molecule, with the atom-numbering scheme.Hydrogen bonds are shown as dashed lines.
Symmetry code: