Poly[bis­(μ-2,6-dimethyl­pyridinium-3,5-dicarboxyl­ato-κ ² O ³:O ⁵)copper(II)]

Abstract

In the title coordination polymer, [Cu(C₉H₈NO₄)₂]_n, the Cu atom, located on a twofold rotation axis, is four coordinate in a distorted square-planar environment. Each 2,6-dimethyl­pyridinium-3,5-dicarboxyl­ate anion bridges two Cu atoms, forming a two-dimensional coordination polymer. A three-dimensional supra­molecular network is built from N—H⋯O hydrogen bonds involving the pyridinium NH and the carboxyl COO groups.

Related literature

For the synthesis of 2,6-dimethyl­pyridine-3,5-dicarboxylic acid, see: Checchi et al. (1959 ▶). For the crystal structures of some of its metal complexes, see: Gao et al. (2007 ▶); Shi et al. (2007 ▶); Zeng et al. (2000 ▶, 2002 ▶).

Experimental

Crystal data

• [Cu(C₉H₈N₂O₄)₂]

• M _r = 451.87

• Orthorhombic,

• a = 8.2003 (16) Å

• b = 16.234 (3) Å

• c = 13.708 (3) Å

• V = 1824.9 (6) ų

• Z = 4

• Mo Kα radiation

• μ = 1.25 mm⁻¹

• T = 291 (2) K

• 0.26 × 0.24 × 0.19 mm

Data collection

• Rigaku R-AXIS RAPID diffractometer

• Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.733, T _max = 0.801

• 16747 measured reflections

• 2097 independent reflections

• 1754 reflections with I > 2σ(I)

• R _int = 0.051

Refinement

• R[F ² > 2σ(F ²)] = 0.033

• wR(F ²) = 0.092

• S = 1.09

• 2097 reflections

• 138 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.41 e Å⁻³

• Δρ_min = −0.29 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002 ▶); 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: SHELXL97.

Supplementary Material

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
N1—H8⋯O3i	0.82 (3)	1.88 (3)	2.698 (2)	177 (3)

Symmetry code: (i) .

supplementary crystallographic information

Comment

To the best of our knowledge, there have been few reports to date on the crystal structure of 2,6-dimethylpyrine-3,5-dicarboxylic acid ligand (Zeng et al., 2000; Zeng et al., 2002: Gao et al., 2007). The crystal structure of 2,6-dimethylpyridinium-3,5-dicarboxylate ligand and Cu atom complex have been reported, namely trans-tetraaquabis (2,6-dimethylpyrinium-3,5-dicarboxylate)cooper(II) tetrahydrate, which is a discrete compound (Shi et al., 2007). In this paper, we report the new two-dimensional title complex, (I), synthesized by the recation of 2,6-dimethylpyrine-3,5-dicarboxylic acid and copper(II) dinitrate in methanol solution.

In the title compound, (Fig. 1), the Cu atom is located on a twofold rotation axis is four coordinated in a square environment that is formed by four carboxylate O atoms from four 2,6-dimethylpyridinium-3,5- dicarboxylate ligands. Each 2,6-dimethylpyridinium-3,5-dicarboxylate ligand bridges two Cu atom to form a two-dimensional supramolecular network parallel the ab plane (Fig. 2). In addition, N1—H8···O3ⁱ hydrogen bonds link these adjacent plane into a three-dimensional supramolecular network (Table 1).

Experimental

2,6-Dimethylpyridine-3,5-dicarboxylic acid was prepared by basic hydrolysis of diethyl 2,6-dimethylpyridine-3,5-dicarboxylate, prepared according to Checchi (1959). Diethyl 2,6-dimethylpyridine-3,5-dicarboxylate (25.1 g, 0.1 mol) and potassium hydroxide (13.44 g, 0.24 mol) were dissolved in 150 ml e thanol and 150 ml water mixed solution, then stirred for three hours under reflux conditions. 10.5 g 2,6-Dimethylpyridine-3,5-dicarboxylic acid, a white precipitate, formed by adjusting pH of solution to 3 with 0.1 M HCl after evaporation of ethanol.

The complex (I) was synthesized with coppert(II) dinitrate (0.368 g, 2 mmol) and 2,6-dimethylpyridine-3,5-dicarboxylic acid (0.390 g, 2 mmol) were dissolved in methanol and the pH was adjusted to 6 with 0.01M sodium hydroxide. Black crystals were separated from the filtered solution after several days.

Refinement

H atoms bound to C atoms were placed in calculated positions and treated as riding on their parent atoms, with C—H = 0.93 Å, 0.97 Å for aromatic and methyl H atoms respectively; U_iso(H) was set to = 1.2U_eq of the carrier atom (1.5 U_eq for methyl H atoms). The H8 atoms bond to N1 atoms were located in a difference Fourier map and refined isotropically.

Figures

Fig. 1.

The molecular structure of (I), showing displacement ellipsoids at the 30% probability level for non-H atoms. [symmetry codes: (I): -x - 1, -y + 1, -z; (II): x - 1, 3/2 - y, -1/2 + z; (III): x, -1/2 - y, -1/2 + z]

Fig. 2.

Part of the polymeric structure of (I), showing a two-dimensional network.

Crystal data

[Cu(C9H8N2O4)2]	F000 = 924
Mr = 451.87	Dx = 1.645 Mg m−3
Orthorhombic, Pbcn	Mo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 12587 reflections
a = 8.2003 (16) Å	θ = 3.2–27.5º
b = 16.234 (3) Å	µ = 1.25 mm−1
c = 13.708 (3) Å	T = 291 (2) K
V = 1824.9 (6) Å3	Bluck, black
Z = 4	0.26 × 0.24 × 0.19 mm

Data collection

Rigaku R-AXIS RAPID diffractometer	2097 independent reflections
Radiation source: fine-focus sealed tube	1754 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.051
T = 291(2) K	θmax = 27.5º
ω scan	θmin = 3.2º
Absorption correction: Multi-scan(ABSCOR; Higashi, 1995)	h = −10→10
Tmin = 0.733, Tmax = 0.801	k = −21→21
16747 measured reflections	l = −17→17

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.033	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.092	w = 1/[σ2(Fo2) + (0.0491P)2 + 0.9342P] where P = (Fo2 + 2Fc2)/3
S = 1.09	(Δ/σ)max = 0.008
2097 reflections	Δρmax = 0.41 e Å−3
138 parameters	Δρmin = −0.29 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.1149 (2)	0.35544 (11)	0.53558 (13)	0.0216 (4)
C2	0.1113 (2)	0.33765 (12)	0.43628 (14)	0.0226 (4)
C3	0.1706 (3)	0.39606 (12)	0.37198 (13)	0.0251 (4)
H1	0.1677	0.3849	0.3055	0.030*
C4	0.2345 (3)	0.47081 (12)	0.40328 (13)	0.0225 (4)
C5	0.2407 (3)	0.48643 (11)	0.50282 (13)	0.0211 (4)
C6	0.0406 (3)	0.25909 (13)	0.39516 (15)	0.0269 (4)
C7	0.2938 (3)	0.53108 (12)	0.32739 (14)	0.0257 (4)
C8	0.3043 (3)	0.56351 (13)	0.54895 (15)	0.0300 (5)
H5	0.2941	0.5595	0.6186	0.045*
H6	0.2427	0.6099	0.5259	0.045*
H7	0.4170	0.5706	0.5320	0.045*
C9	0.0530 (3)	0.30107 (14)	0.61494 (15)	0.0331 (5)
H2	0.1078	0.3142	0.6749	0.050*
H3	0.0736	0.2446	0.5984	0.050*
H4	−0.0621	0.3094	0.6227	0.050*
Cu1	0.0000	0.148168 (18)	0.2500	0.02018 (13)
H8	0.186 (3)	0.4388 (17)	0.621 (2)	0.042 (8)*
N1	0.1800 (2)	0.42800 (10)	0.56291 (12)	0.0225 (4)
O1	−0.0813 (2)	0.22887 (11)	0.43090 (13)	0.0466 (5)
O2	0.1169 (2)	0.23282 (9)	0.32017 (10)	0.0333 (4)
O3	0.2050 (3)	0.54134 (12)	0.25578 (11)	0.0442 (5)
O4	0.4295 (2)	0.56494 (9)	0.34300 (11)	0.0337 (4)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0243 (10)	0.0224 (9)	0.0180 (9)	0.0001 (8)	−0.0003 (7)	0.0006 (7)
C2	0.0248 (10)	0.0226 (9)	0.0203 (9)	−0.0015 (8)	−0.0012 (7)	−0.0027 (7)
C3	0.0331 (11)	0.0271 (10)	0.0152 (8)	−0.0015 (8)	−0.0020 (7)	−0.0029 (7)
C4	0.0283 (10)	0.0217 (9)	0.0175 (8)	−0.0017 (8)	−0.0009 (7)	0.0015 (7)
C5	0.0239 (10)	0.0207 (9)	0.0186 (9)	0.0000 (8)	−0.0020 (7)	0.0002 (7)
C6	0.0319 (11)	0.0239 (10)	0.0250 (10)	−0.0044 (8)	−0.0064 (8)	−0.0013 (8)
C7	0.0382 (12)	0.0203 (9)	0.0186 (9)	0.0020 (9)	0.0036 (8)	0.0015 (7)
C8	0.0399 (12)	0.0254 (10)	0.0246 (10)	−0.0060 (9)	−0.0031 (8)	−0.0051 (8)
C9	0.0442 (13)	0.0325 (11)	0.0225 (10)	−0.0085 (10)	0.0067 (9)	0.0033 (8)
Cu1	0.0283 (2)	0.01488 (19)	0.01735 (19)	0.000	−0.00329 (12)	0.000
N1	0.0294 (9)	0.0249 (8)	0.0132 (7)	−0.0018 (7)	−0.0006 (6)	−0.0012 (6)
O1	0.0439 (11)	0.0449 (10)	0.0511 (10)	−0.0222 (9)	0.0102 (9)	−0.0123 (8)
O2	0.0440 (9)	0.0283 (7)	0.0277 (7)	−0.0087 (7)	−0.0004 (7)	−0.0095 (6)
O3	0.0507 (11)	0.0592 (12)	0.0228 (8)	−0.0022 (9)	−0.0051 (7)	0.0161 (7)
O4	0.0442 (10)	0.0279 (8)	0.0290 (8)	−0.0094 (7)	0.0034 (7)	0.0081 (6)

Geometric parameters (Å, °)

C1—N1	1.346 (3)	C7—O4	1.259 (3)
C1—C2	1.392 (3)	C8—H5	0.9600
C1—C9	1.490 (3)	C8—H6	0.9600
C2—C3	1.383 (3)	C8—H7	0.9600
C2—C6	1.510 (3)	C9—H2	0.9600
C3—C4	1.390 (3)	C9—H3	0.9600
C3—H1	0.9300	C9—H4	0.9600
C4—C5	1.389 (3)	Cu1—O2	1.9322 (15)
C4—C7	1.509 (3)	Cu1—O2i	1.9322 (15)
C5—N1	1.351 (2)	Cu1—O4ii	1.9455 (15)
C5—C8	1.496 (3)	Cu1—O4iii	1.9455 (15)
C6—O1	1.216 (3)	N1—H8	0.82 (3)
C6—O2	1.277 (3)	O4—Cu1iv	1.9455 (15)
C7—O3	1.234 (3)
N1—C1—C2	117.53 (17)	C5—C8—H6	109.5
N1—C1—C9	116.75 (17)	H5—C8—H6	109.5
C2—C1—C9	125.72 (18)	C5—C8—H7	109.5
C3—C2—C1	118.26 (17)	H5—C8—H7	109.5
C3—C2—C6	118.44 (17)	H6—C8—H7	109.5
C1—C2—C6	123.26 (17)	C1—C9—H2	109.5
C2—C3—C4	122.31 (17)	C1—C9—H3	109.5
C2—C3—H1	118.8	H2—C9—H3	109.5
C4—C3—H1	118.8	C1—C9—H4	109.5
C5—C4—C3	118.47 (17)	H2—C9—H4	109.5
C5—C4—C7	123.17 (17)	H3—C9—H4	109.5
C3—C4—C7	118.36 (17)	O2—Cu1—O2i	89.32 (10)
N1—C5—C4	117.21 (17)	O2—Cu1—O4ii	165.38 (7)
N1—C5—C8	117.25 (16)	O2i—Cu1—O4ii	91.17 (7)
C4—C5—C8	125.51 (17)	O2—Cu1—O4iii	91.17 (7)
O1—C6—O2	126.3 (2)	O2i—Cu1—O4iii	165.38 (7)
O1—C6—C2	120.40 (19)	O4ii—Cu1—O4iii	92.03 (10)
O2—C6—C2	113.20 (18)	C1—N1—C5	126.19 (16)
O3—C7—O4	126.7 (2)	C1—N1—H8	119 (2)
O3—C7—C4	116.5 (2)	C5—N1—H8	115 (2)
O4—C7—C4	116.80 (18)	C6—O2—Cu1	113.26 (14)
C5—C8—H5	109.5	C7—O4—Cu1iv	117.02 (14)

Symmetry codes: (i) −x, y, −z+1/2; (ii) x−1/2, y−1/2, −z+1/2; (iii) −x+1/2, y−1/2, z; (iv) x+1/2, y+1/2, −z+1/2.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H8···O3v	0.82 (3)	1.88 (3)	2.698 (2)	177 (3)

Symmetry codes: (v) x, −y+1, z+1/2.