Bis(2,1,3-benzoselenadiazole-κN)dichloridozinc(II)

In the title complex, [ZnCl2(C6H4N2Se)2], the ZnII center is tetracoordinated by a Cl2N2 donor set in a distorted tetrahedral geometry. Some of the distortion from the ideal tetrahedral geometry might be ascribed to two agostic Z⋯H interactions The two 2,1,3-benzoselenadiazole ligands are each essentially planar and form a dihedral angle of 35.06 (9)°. An interesting feature of the crystal packing is the observation of short intermolecular contacts between Se and Se, Se and N, and N and N atoms. These arise as a result of three-center bridging of adjacent molecules into chains along the b axis. The crystal structure is stablilized by π–π interactions [minimum centroid–centroid distance = 3.5694 (18) Å].

In the title complex, [ZnCl 2 (C 6 H 4 N 2 Se) 2 ], the Zn II center is tetracoordinated by a Cl 2 N 2 donor set in a distorted tetrahedral geometry. Some of the distortion from the ideal tetrahedral geometry might be ascribed to two agostic ZÁ Á ÁH interactions The two 2,1,3-benzoselenadiazole ligands are each essentially planar and form a dihedral angle of 35.06 (9) . An interesting feature of the crystal packing is the observation of short intermolecular contacts between Se and Se, Se and N, and N and N atoms. These arise as a result of three-center bridging of adjacent molecules into chains along the b axis. The crystal structure is stablilized byinteractions [minimum centroid-centroid distance = 3.5694 (18) Å ].
The structure of (I) comprises a neutral ZnCl 2 L 2 molecule (L= 2,1,3-benzoselenadiazole ligand), Fig. 1. The Zn II ion is tetra-coordinated by two Clions and two N atoms derived from the L ligands. The L ligands are each essentially planar with the maximum deviation of 0.028 (2)Å being for atom N1 in one ligand and 0.044 (2) Å for the N3 atom in the other ligand. The dihedral angle between the their mean planes is 35.06 (9)°. The distorted tetrahedral geometry can be indicated by the bond angles subtended at Zn: N-Zn-N = 111.13 (9)°, Cl-Zn-Cl = 122.58 (4)°, and N-Zn-Cl in the range of 100.70 (6) -110.81 (7)°. Some of the distortion from the ideal tetrahedral geometry might be ascribed to two agostic Zn···H interactions, Table 1.
The interesting feature of the crystal packing is the observation of short intermolecular contacts between Se and Se, Se and N, and N and N atoms (Table 1). These arise as a result of three-center bridging of adjacent molecules into chains along the b-axis, Fig. 2. The crystal is further stabilized by π-π interactions with the shortest of these being 3.5694 (18) Å for Cg(C7/C12/N4/Se2/N3)···Cg(C7-C12) i for i: -x, 2-y, -z.

Experimental
A slurry of 2,1,3-benzoselenadiazole (1 g, 5.4 mmol) and anhydrous zinc chloride (270 mg, 2.72 mmol) in dry methanol (15 ml) was heated at 343-353 K for 2 h. After completion of the reaction, the mixture was allowed to cool to room temperature and the precipitate (I) was collected by filtration. Recrystallization of (I) from 40% methanol in chloroform afforded a yellow microcrystalline solid (1.16 g, 85% yield).

Refinement
All H atoms were placed in calculated positions with C-H = 0.93 Å, and with U iso =1.2U eq (C).