Crystal structures of [(μ2-L1)dibromidodicopper(II)] dibromide and poly[[(μ2-L1)diiodidodicopper(I)]-di-μ-iodido-dicopper(I)], where L1 is 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane

The reaction of the hexathiapyrazinophane ligand, 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane, with copper(II) dibromide lead to the formation of a binuclear complex. Reaction with copper(I) iodide also gave a binuclear complex, which is bridged by a Cu2I2 unit to form a two-dimensional coordination polymer.

The reaction of the hexathiapyrazinophane ligand, 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane (L1), with copper(II) dibromide led to the formation of a binuclear complex, [ 2 -2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)pyrazinophane]bis[bromidocopper(II)] dibromide, [Cu 2 Br 2 (C 16 H 24 N 2 S 6 )]Br 2 , (I). The complex possesses inversion symmetry with the pyrazine ring being situated about a center of symmetry. The ligand coordinates to the copper(II) atom in a bis-tetradentate manner and the copper atom has a fivefold NS 3 Br coordination environment with a distorted shape. The reaction of ligand L1 with copper(I) iodide also gave a binuclear complex, which is bridged by a Cu 2 I 2 unit to form a two-dimensional coordination polymer, poly [[ 2 -2,5,8,11,14,17hexathia-[9.9](2,6,3,5)-pyrazinophane]tetra--iodido-tetracopper(I)], [Cu 4 I 4 -(C 16 H 24 N 2 S 6 )] n , (II). The binuclear unit possesses inversion symmetry with the pyrazine ring being located about a center of symmetry. The Cu 2 I 2 unit is also located about an inversion center. The two independent copper(I) atoms are both fourfold coordinate. That coordinating to the ligand L1 in a bistridentate manner has an NS 2 I coordination environment and an irregular shape, while the second copper(I) atom, where L1 coordinates in a bismonodentate manner, has an SI 3 coordination environment with an almost perfect tetrahedral geometry. In the crystal of I, the cations and Br À anions are linked by a number of C-HÁ Á ÁS and C-HÁ Á ÁBr hydrogen bonds, forming a supramolecular network. In the crystal of II, the two-dimensional coordination polymers lie parallel to the ab plane and there are no significant inter-layer contacts present.
Reaction of L1 with copper(I) iodide also gave a binuclear complex, which is bridged by a Cu 2 I 2 unit to form a twodimensional coordination polymer, poly-[( 2 -L1)diiodido-)diiodidodicopper(I)di(-iodido)dicopper(I)], (II); see Fig. 3. The binuclear complex possesses inversion symmetry with the pyrazine ring being located about a center of symmetry. The Cu 2 I 2 unit is also located about an inversion center. Selected bond distances and angles are given in Table 2. The two independent copper(I) atoms, Cu1 and Cu2, are both fourfold coordinate. Atom Cu1 coordinates to the ligand L1 in a tridentate fashion and has an NS 2 I coordination environment. The fourfold index parameter 4 is 0.77 indicating a very irregular shape ( 4 = 1 for a perfect tetrahedral environment, 0 for a perfect square-planar environment and 0.85 for a perfect trigonal-pyramidal environment; Yang et al., 2007). There are three chelate rings, two of which are five-membered (Cu1/N1/ C2/C3/S1 and Cu1/S1/C4/C5/S2) and one eight-membered (Cu1/N1/C1/C8/S3/C7/C6/S2). The second copper(I) atom, Cu2, coordinates to L1 in a monodentate fashion and has an SI 3 environment with an almost perfect tetrahedral geometry; here the fourfold index parameter 4 is 0.91. A view of the molecular structure of complex I, with atom labelling for the asymmetric unit; symmetry code: (i) Àx + 1, Ày + 1, Àz. Displacement ellipsoids are drawn at the 50% probability level.

Supramolecular features
In the crystal of I, the cations are linked by pairs of C6-H6BÁ Á ÁS1 i hydrogen bonds to form chains along the a-axis direction. Chains are also formed along the b-axis direction via C5-H5AÁ Á ÁS3 ii hydrogen bonds (Table 3). These interactions result in the formation of a supramolecular network that lies parallel to the ab plane ( Fig. 4). There are also a large number of C-HÁ Á ÁBr contacts present involving the anion, Br2 À , strengthening the supramolecular network ( Fig. 5 and Table 3). There are no significant inter-layer contacts present in the crystal.

Figure 4
A view along the c axis of the crystal packing of I. The C-HÁ Á ÁS hydrogen bonds are shown as dashed lines (see Table 3). For clarity, the Br À anion and the H atoms not involved in these intermolecular interactions have been omitted.

Figure 5
A view along the b axis of the crystal packing of I. The C-HÁ Á ÁS and C-HÁ Á ÁBr À hydrogen bonds (Table 3) are shown as dashed lines (see Table 3). For clarity, only the H atoms involved in these intermolecular interactions have been included.

Figure 6
A view along the c axis of the two-dimensional structure of complex II. For clarity, H atoms have been omitted.
Synthesis of complex [(l 2 -L1)dibromodo dicopper(II)] dibromide (I): A solution of L1 (15 mg, 0.03 mmol) in CHCl 3 (10 ml) was introduced into a 16 mm diameter glass tube and layered with MeCN (2 ml) as a buffer zone. Then a solution of CuBr 2 (7 mg, 0.03 mmol) in MeCN (5 ml) was added gently to avoid possible mixing. The glass tube was sealed and left in the dark at room temperature for at least 3 weeks, whereupon brown crystals of complex I were isolated in the buffer zone.
Synthesis  diameter glass tube and layered with MeCN (2 ml) as a buffer zone. A solution of CuI (6 mg, 0.03 mmol) in MeCN (5 ml) was added gently to avoid possible mixing. The glass tube was sealed under an atmosphere of nitrogen and left in the dark at room temperature for at least 3 weeks, whereupon small orange crystals of complex II were isolated in the buffer zone.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. The C-bound H atoms were included in calculated positions and treated as riding on their parent atoms: C-H = 0.98 Å for I and 0.97 Å for II, with U iso (H) = 1.2U eq (C). Intensity data were measured using a STOE IPDS-1 onecircle diffractometer. For the triclinic system often only 93% of the Ewald sphere is accessible, which explains why the alerts diffrn_reflns_laue_measured_fraction_full value (0.94) below minimum (0.95) for both compounds I and II are given. This involves 145 random reflections out of the expected 2336 for the IUCr cutoff limit of sin / = 0.60 for I, and 155 random reflections out of the expected 2600 reflections for II. The residual electron-density peaks are approximately 1Å from the halogen atoms in both structures.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Br1 0.19307 (12) 0.19827 (12) 0.45400 (7)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 2.25 e Å −3 Δρ min = −2.58 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.