Bis[1,3-bis(2-cyanophenyl)triazenido]mercury(II)

In the title compound, [Hg(C14H8N5)2], the central atom is four-coordinated by two bidentate 1,3-bis(2-cyanophenyl)triazenide ligands in a distorted square-planar geometry. The asymmteric unit is composed of one ligand molecule and one HgII ion, which is disordered over two sites, one lying on an inversion center and the other on a general position with site-occupancy factors of 0.2378 (7) and 0.3811 (7), respectively. The monomeric molecules of the complex are linked into pairs through non-classical C—H⋯N hydrogen bonds. The resulting dimeric units are assembled by translation along the crystallographic c axis into chains linked through secondary π–π interactions [centroid–centroid distances = 3.685 (2) and 3.574 (2) Å], as well as C—H⋯π stacking interactions, resulting in a two-dimensional architecture.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2202). Recently, the study of transition metal complexes containing 1,3-diaryltriazenide ions has been increased due to the potential reactivity of these ligands (Vrieze & Koten, 1987). This anion is a three-atom donor ligand that can act as a monodentate group, a chelating ligand or a bridging ligand between two metal centers (Hursthouse et al., 1993).
The molecular structure of the title compound is shown in Fig. 1. There is a high disorder of Hg atom in the complex.
The Hg(II) atom was disordered over 3 sites (only 2 of them are symmetrically independent). Hg1:Hg1A:Hg2 atoms are disordered in ratio 0.38:0.38:0.24. The central atom in this compound is coordinated by two symmetrically related triazenide ions. Each Hg II atom is four-coordinated by two nitrogen atoms N1, and N3 of two 1,3-bis(2-cyano)phenyl]triazene fragments which act as bidentate ligands. The arrangement of the four donor atoms around Hg(II) atom results in a distorted square planar geometry.
In the lattice of the title compound, the monomeric [Hg(C 14 H 8 N 5 ) 2 ] molecules are linked into pairs through non-classical C-H···N hydrogen bonds (details are provided in Table 1). The resulting dimeric units are assembled by translation along the crystallographic c axis to unidimensional chains linked through secondary π-interactions. Consequently, 1-D chains formed by C-H···N hydrogen bonds are connected with one another by π-π and C-H···π stacking interactions, resulting in the 2-D architecture (Fig. 2). These π-π stacking interactions are present between aromatic rings with centroid-centroid distances of 3.685 (2) and 3.574 (2) Å and also between C-H group of phenyl rings with aromatic rings with H···π distance of 2.96 Å for C10-H10A···Cg; Cg is the centroid of C7-C12 ring.

Experimental
Anhydrous methanolic solution of [1,3-bis(2-cyano)phenyl]triazene (0.247 g) was added to anhydrous methanolic solution of mercury(II) acetate ( 0.160 g). After several hours, the mixture was filtered, the product washed with methanol, the yellow supplementary materials sup-2 precipitate thus obtained was dissolved in diethyl ether and stored in a freezer. After 14 days, well formed orange-red crystals were produced which decompose above 523 K.

Refinement
There is a high disorder of Hg atom in the comples. The Hg atom in the complex was disordered over 3 sites (only 2 of them are symmetrically independent), where disorder was refined as free variable (using FVAR instrcution).
Positions of H-atoms were calculated and refined in isotropic approximation in riding mode with (C-H = 0.95 Å) and There is a high positive residual density of 2.67 e Å -3 near the Hg1 center (distance 0.85% A) due to considerable absorption effects which could not be completely corrected. Fig. 1. Molecular structure of the title compound, with ellipsoids drawn at 50% probability level: Hg1 has been omitted for clarity. Symmetry code to generate atoms with label "a": -x + 1, y, -z + 1/2.