Bis(2-propyl-1H-imidazol-3-ium) bis­(pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)cadmate(II)

Gui-Ying Dong; Tong-Fei Liu; Cui-Hong He; Xiao-Chen Deng; Xiao-Ge Shi

doi:10.1107/S1600536811024792

. 2011 Jun 30;67(Pt 7):m1007. doi: 10.1107/S1600536811024792

Bis(2-propyl-1H-imidazol-3-ium) bis(pyridine-2,6-dicarboxylato-κ³ O ²,N,O ⁶)cadmate(II)

Gui-Ying Dong ^a,^*, Tong-Fei Liu ^a, Cui-Hong He ^a, Xiao-Chen Deng ^b, Xiao-Ge Shi ^b

PMCID: PMC3151894 PMID: 21836832

Abstract

The title salt, (C₆H₁₁N₂)₂[Cd(C₇H₃NO₄)₂], displays a discrete mononuclear structure, in which the central Cd^II atom is six-coordinated in a distorted octahedral coordination geometry by two N and four O atoms from two different pyridine-2,6-dicarboxylate anions in an O ²,N,O ⁶-tridentate chelation mode. The crystal packing is stabilized by N—H⋯O hydrogen bonds and π–π interactions [centroid–centroid distance = 3.576 (5) Å].

Related literature

For background to and the biological activity of pyridine-2,6-dicarboxylic acid, see: Hay et al. (2003 ▶). For related complexes, see: Dong et al. (2006 ▶); Guerriero et al. (1987 ▶); Kjell et al. (1993 ▶); Abboud et al. (1998 ▶).

Experimental

Crystal data

(C₆H₁₁N₂)₂[Cd(C₇H₃NO₄)₂]
M _r = 664.95
Monoclinic,
a = 19.928 (4) Å
b = 9.5038 (19) Å
c = 15.073 (3) Å
β = 109.90 (3)°
V = 2684.2 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.88 mm⁻¹
T = 295 K
0.22 × 0.12 × 0.08 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.796, T _max = 0.808
11223 measured reflections
2364 independent reflections
2238 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.065
S = 1.19
2364 reflections
186 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.46 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1998 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811024792/aa2014sup1.cif

e-67-m1007-sup1.cif^{(20.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811024792/aa2014Isup2.hkl

e-67-m1007-Isup2.hkl^{(116.3KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2B⋯O2ⁱ	0.86	1.93	2.753 (3)	160
N3—H3B⋯O4ⁱⁱ	0.86	1.84	2.690 (3)	173

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

Acknowledgments

The authors thank Hebei United University for supporting this work.

supplementary crystallographic information

Comment

The pyridine-2,6-dicarboxylic (dipicolinic) acid is now recognized to be a major component of bacterial spores, which is used in a variety of processes as an enzyme inhibitor, plant preservative and food sanitizer (Hay et al. 2003). Pyridine-2,6-dicarboxylate has proved to be a versatile ligand with N,O-chelation and adopts diverse coordination modes (Guerriero et al., 1987; Kjell et al., 1993; Abboud et al., 1998; Dong et al.,2006). Recent efforts of our laboratory to synthesize coordination polymers with pyridine-2,6-dicarboxylic acid and 2-propylimidazole with transition metals resulted in the synthesis of the title complex (I).

In the title compound, the Cd^II is octahedrally coordinated by two tridentate dipicolinate ligands via their O and N atoms. In the crystal structure, adjacent molecules are linked via strong N—H···O hydrogen bonds into chains parallel to the b axis, see Fig. 2. Also there are π-π interactions between the centroids of adjacent pyridine rings. For Cg1 (the centroid of ring N1,C1—C5) and Cg1^a (ring N1^a,C1^a—C5^a) [symmetry code (a):-x,-y,-z + 1), the centroid–centroid distance is 3.576 (5)Å and the dihedral angle is 12.43 (3)°, this may further stabilize the structure.

Experimental

A mixture of cadmium(II) nitrate tetrahydrate (308.49 mg, 1 mmol) was added to a slightly basic (pH > 8) solution of pyridine-2,6-dicarboxylic acid (334 mg, 2 mmol), followed by the addition of 2-propylimidazole (440 mg, 4 mmol) with stirring. The reaction mixture was filtered and the filtrate was allowed to stay at room temperature. Colourless prism-shaped crystals were obtained after one week (yield: 0.132 g, 20%). Analysis for C₂₆H₂₈CdN₆O₈ (%): calculated C 46.96, H 4.24,N 12.64; found C 46.85, H 4.13 N 12.57.