catena-Poly[[(benzil bis{[(pyridin-2-yl)methylidene]hydrazone}-κ4 N,N′,N′′,N′′′)mercury(II)]-μ-chlorido-[dichloridomercury(II)]-μ-chlorido]

In the title coordination polymer, [Hg2Cl4(C26H20N6)]n, one HgII ion is coordinated by four N atoms from the benzylbis((pyridin-2-yl)methylidenehydrazone) ligand and two Cl− ions in a very distorted cis-HgCl2N4 octahedral geometry. The other HgII ion is coordinated in a distorted tetrahedral geometry by four Cl− ions. Bridging chloride ions link the HgII ions into a chain propagating in [010]: the Hg—Cl bridging bonds are significantly longer than the terminal bonds. The dihedral angle between the central benzene rings of the ligand is 83.3 (2)°. The packing is consolidated by weak C—H⋯Cl hydrogen bonds and C—H⋯π interactions.

In the title coordination polymer, [Hg 2 Cl 4 (C 26 H 20 N 6 )] n , one Hg II ion is coordinated by four N atoms from the benzylbis((pyridin-2-yl)methylidenehydrazone) ligand and two Cl À ions in a very distorted cis-HgCl 2 N 4 octahedral geometry. The other Hg II ion is coordinated in a distorted tetrahedral geometry by four Cl À ions. Bridging chloride ions link the Hg II ions into a chain propagating in [010]: the Hg-Cl bridging bonds are significantly longer than the terminal bonds. The dihedral angle between the central benzene rings of the ligand is 83.3 (2) . The packing is consolidated by weak C-HÁ Á ÁCl hydrogen bonds and C-HÁ Á Á interactions.

Comment
Research of polyimmine compound is well established currently of great interest because of their potential applications as useful organic ligands, in which the amine nitrogen atoms have strong coordination ability to transition metal ions and recongnition function (Bai et al., 2005;Pal et al., 2000;Chowdhury et al., 2003;Drew et al., 2006;Sun et al., 2006). In this paper, we report the synthesis and crystal structure of the title compound.
The molecular structure of the title bimetallic coordination polymer Cl 2 Hg-Cl-(C 26 H 20 N 6 )Hg-Cl-HgCl 2 (I) is shown in Fig. 1. Atom Hg2 is four-coordinated in a distorted tetrahedral coordination geometry by two bridging Cl atoms and two terminal Cl atoms. The bond distances of Hg-N are in the range of 2.435 (3) -2.5558 (3) Å, the bond distances of Hg-Cl are in the range of 2.3308 (12) -2.7777 (10) Å. N′,N′-bis[1-(pyridin-2-yl)methylidene]benzil dihydrazone acts as cleating ligand here. The packing and hydrogen bonding (Table 1) is shown in Fig. 2. In addition, a C-H···π interaction contributes to the stabilization of the crystal packing.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 Å and U iso (H) = 1.2U eq (C).

[dichloridomercury(II)]-µ-chlorido]
Crystal data [HgCl 4 (C 26  Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.