Poly[tris­[μ2-2-(pyrazol-1-yl)pyrazine]hexa-μ1,3-thio­cyanato-tricadmium(II)]

Lin Yan Yang; Jing Min Shi

doi:10.1107/S1600536808032285

. 2008 Oct 11;64(Pt 11):m1387. doi: 10.1107/S1600536808032285

Poly[tris[μ₂-2-(pyrazol-1-yl)pyrazine]hexa-μ_1,3-thiocyanato-tricadmium(II)]

Lin Yan Yang ^a, Jing Min Shi ^a,^*

PMCID: PMC2959520 PMID: 21580840

Abstract

The asymmetric unit of the title crystal structure, [Cd₃(NCS)₆(C₇H₆N₄)₂]_n, contains two independent Cd^II ions, one of which is located on a crystallographic inversion center. Each independent Cd^II ion is in a slightly distorted octahedral coordination environment, but the disortion from ideally octahedral is greater in the environment of the Cd^II ion on a general position. Both thiocyanate ligands act as bridges connecting independent Cd^II ions, and the 2-(pyrazol-1-yl)pyrazine ligands chelate one Cd^II ion in a bidentate mode while the remaining N atom of the pyrazine ring coordinates to a symmetry-related Cd^II ion, forming a two-dimensional structure parallel to (211).

Related literature

For background information, see: Shi, Sun, Liu et al. (2006 ▶); Shi, Sun, Zhang et al. (2006 ▶).

Experimental

Crystal data

[Cd₃(NCS)₆(C₇H₆N₄)₂]
M _r = 978.00
Triclinic,
a = 7.0309 (9) Å
b = 8.6178 (12) Å
c = 13.7373 (18) Å
α = 87.889 (2)°
β = 85.173 (2)°
γ = 68.060 (2)°
V = 769.32 (18) Å³
Z = 1
Mo Kα radiation
μ = 2.50 mm⁻¹
T = 298 (2) K
0.38 × 0.16 × 0.10 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.450, T _max = 0.788
4043 measured reflections
2805 independent reflections
2625 reflections with I > 2σ(I)
R _int = 0.013

Refinement

R[F ² > 2σ(F ²)] = 0.022
wR(F ²) = 0.056
S = 1.06
2805 reflections
196 parameters
H-atom parameters constrained
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.51 e Å⁻³

Data collection: SMART (Bruker, 1997 ▶); cell refinement: SAINT (Bruker, 1997 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808032285/lh2704sup1.cif

e-64-m1387-sup1.cif^{(19KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808032285/lh2704Isup2.hkl

e-64-m1387-Isup2.hkl^{(137.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Cd1—N2	2.286 (3)
Cd1—N7ⁱ	2.426 (2)
Cd1—S2	2.6832 (8)
Cd2—N1ⁱⁱ	2.244 (2)
Cd2—N3	2.303 (3)
Cd2—N5	2.385 (2)
Cd2—N4	2.436 (2)
Cd2—S1	2.6603 (9)
Cd2—S3	2.7427 (8)

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Symmetry codes: (i) Inline graphic ; (ii) .

supplementary crystallographic information

Comment

For a considerable time, interest has focused on polymeric coordination compounds because such new coordination polymers may afford new materials with useful properties, such as catalytic activity, micro-porosity, electrical conductivity, non-linear optical activity and magnetic coupling behavior. The thiocyanide anion is a very common bridging ligand and many muti-nuclear complexes containing this ligand have been reported. Some of these complexes exhibit interesting magnetic coupling properties (Shi, Sun, Liu et al., 2006; Shi, Sun, Zhang et al., 2006)). The 2-(pyrazole-1-yl)-pyrazine molecule can act as a bridge ligand due to its structural character and up till now no crystal structures of complexes with this ligand have been reported. Under the motivation of preparing new coordination polymers containing mixed bridging ligands, we have synthesized the title coordination polymer and herein we report its crystal structure (I).

Fig. 1 shows the coordination around each independent Cd^II ion. Atom Cd1 is located on a crystallographic inversion center. In the crystal structure thiocyanade anions act as bridging ligands and connect symmetry related Cd^II ions [with Cd···Cd = 5.8122 (6)Å for Cd1···Cd2 and 5.7411 (7) Å for Cd2···Cd2ⁱⁱ; symmetry code: (ii) -x+1, -y+1, -z+1] forming an eight-membered ring which acts as a repeat unit of the structure in one-dimension [Fig. 2]. The 2-(pyrazole-1-yl)-pyrazine ligand functions as a tridentate bridging ligand and coordinates to symmetry related Cd^II ions [with a Cd···Cd separation of 7.6144 (7)Å] connecting the structure further into two-dimensions. Figure 2 also shows that in the two-dimensional structure there are two different types of rings formed by the 2-(pyrazole-1-yl)-pyrazine bridging ligand. An 18-membered ring consists of four Cd^II ions, two thiocyanato ligands and two 2-(pyrazole-1-yl)-pyrazine bridging ligands while a 26-membered ring consists of two 2-(pyrazole-1-yl)-pyrazine bridging ligands, four thiocyanade ligands and six Cd^II ions. The 18-membered rings and the 26-membered rings are arranged alternately in the two-dimensional structure.

Experimental

7 ml 3-(pyrazole-2-yloxy)-pyridine (0.0365 g, 0.250 mmol) methanol solution, 7 ml C d(ClO₄)₂6H₂O (0.1048 g, 0.250 mmol) H₂O solution and 4 ml NaSCN (0.0405 g, 0.500 mmol) H₂O solution were mixed together and stirred for a few minutes. Colorless single crystals were obtained after allowing the filtrate to stand at room temperature for four months.