(2,2′-Bipyridine)bis­(3-carboxy­pyrazine-2-carboxyl­ato)copper(II) dihydrate

Hossein Aghabozorg; Mahdieh Parvizi; Elahe Sadrkhanlou

doi:10.1107/S1600536808022885

. 2008 Jul 26;64(Pt 8):m1067. doi: 10.1107/S1600536808022885

(2,2′-Bipyridine)bis(3-carboxypyrazine-2-carboxylato)copper(II) dihydrate

Hossein Aghabozorg ^a,^*, Mahdieh Parvizi ^b, Elahe Sadrkhanlou ^c

PMCID: PMC2961978 PMID: 21203048

Abstract

The title six-coordinated distorted octahedral complex, [Cu(C₆H₃N₂O₄)₂(C₁₀H₈N₂)]·2H₂O, consists of two 3-carboxypyrazine-2-carboxylate anions and one 2,2′-bipyridine ligand. There is a twofold rotation axis positioned at the Cu^II center. The N atoms of the pyrazine ring occupy the axial positions and two proton-transferred O atoms of tbe acid together with the two N atoms of the 2,2′-bipyridine ligand complete the equatorial plane. The interactions existing in the crystal structure are intermolecular O—H⋯O hydrogen bonds, and C—H⋯O and C—O⋯π interactions (O⋯π =3.145 Å, C—O⋯π = 149.75°).

Related literature

There are several compounds made from pyrazine-2,3-dicarboxylic acid, but most of them are in a polymeric form; see, for example: Tombul et al. (2007 ▶, 2008 ▶). For related literature, see: Egli & Sarkhel (2007 ▶).

Experimental

Crystal data

[Cu(C₆H₃N₂O₄)₂(C₁₀H₈N₂)]·2H₂O
M _r = 589.96
Monoclinic,
a = 18.3080 (8) Å
b = 9.2168 (4) Å
c = 16.3235 (7) Å
β = 122.480 (5)°
V = 2323.59 (18) Å³
Z = 4
Mo Kα radiation
μ = 1.01 mm⁻¹
T = 100 (2) K
0.20 × 0.20 × 0.20 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.823, T _max = 0.823
14982 measured reflections
3500 independent reflections
3289 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.023
wR(F ²) = 0.063
S = 1.04
3500 reflections
177 parameters
H-atom parameters constrained
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); 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/S1600536808022885/om2248sup1.cif

e-64-m1067-sup1.cif^{(18.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808022885/om2248Isup2.hkl

e-64-m1067-Isup2.hkl^{(171.7KB, 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
O3—H3O⋯O5ⁱ	0.88	1.66	2.5390 (12)	170
O5—H5A⋯O1	0.84	1.89	2.7218 (13)	173
O5—H5B⋯O4ⁱⁱ	0.86	1.84	2.6989 (13)	177
C7—H7A⋯O2ⁱⁱ	0.95	2.57	3.1144 (14)	117
C8—H8A⋯O2ⁱⁱ	0.95	2.45	3.0433 (13)	121
C9—H9A⋯O5ⁱⁱⁱ	0.95	2.55	3.2168 (13)	127

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

supplementary crystallographic information

Comment

The structure consists of [Cu(2,3-pzdcH)₂(2,2'- bpy)]. 2H₂O, where pzdcH₂ and 2,2'-bpy are pyrazine-2,3-dicarboxylic acid and 2,2'-bipyridine, respectively. The presence of bidentate mono anionic (pzdcH)^- and neutral 2,2'-bipyridine ligands results in a neutral complex. The asymmetric unit is given in Fig. 1. The obtained hexacoordinated geometry is distorted octahedral. The bond lengths and angles around the Cu^II center are all in accordance with the geometrical steric effects.

There is a 2-fold rotation axis positioned at Cu^II center, transforming one half of the compound to the other.

The main interaction responsible for stabilizing such a framework is O–H···O hydrogen bonds. The water molecule participates in two hydrogen bonds relating two neighboring complexes. There is also a weaker C–H···O which joins the third complex to the series.

The O3–H3O···O5(x, -y, z - 1/2, 1.664 Å) and O5–H5B···O4 (-x + 3/2, -y + 1/2, -z, 1.839 Å) form hydrogen-bonded chains described by C²₂(14) graph-set descriptor (Fig. 2). Expansion of these chains results in layer. Furthermore, the C–H···O interactions between the complexes themselves help in the stabilization of the layers. In the third dimension, there is a similar layer at about a 4.1 Å distance. These layers are connected to each other via a fascinating C–O···π interaction by C6–O3 and a pyrazine ring (Fig. 3). All factors including O···π distance (3.145 Å), C–O···π angle (α = 149.75°) and dihedral angle between the planes defined by X₂C–O and the aromatic system (ω = 79.18°), are in the mentioned range as in the reference [Egli & Sarkhel, 2007].

Figure 4 represents the packing diagram of this crystal lattice.

Experimental

To a 10 ml of a stirring aqueous solution of pyrazine-2,3-dicarboxylic acid (0.084 g, 0.5 mmol) and 2,2'- bipyridine (0.078 g, 0.5 mmol), was added a 0.5 molar equivalent of CuSO₄. 5 H₂O (0.062 g, 0.25 mmol) at room temperature. A neutral copper(II) complex, [Cu(pzdcH)₂(2,2'- bpy)]. 2H₂O, was isolated as very light blue crystals. Slow evaporation of the solvent result in product complex in a week.