catena-Poly[[(pyridine-[kappa]N)copper(II)]-[mu]₃-pyridine-2,6-dicarboxylato-[kappa]³O²:O^2',N,O⁶:O^6']

In the title compound, [Cu(C₇H₃NO₄)(C₅H₅N)]_n, the Cu^II atom is in a slightly distorted octa­hedral coordination environment. Each Cu^II atom is bound to two N atoms and one O atom of the pyridine­dicarboxyl­ate (PDA) ligand in a tridentate manner, one N atom of the pyridine mol­ecule and two bridging carboxyl­ate O atoms of adjacent PDA ligands, leading to a linear one-dimensional chain running along the c axis. These chains are further assembled via weak C-H...O and [pi]-[pi] inter­actions into a three-dimensional supra­molecular network structure. The centroid-centroid distance between the [pi]-[pi] inter­acting pyridine rings is 3.9104 (13) Å. The two N atoms are trans to each other with respect to Cu.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.029
• wR factor = 0.074
• Data-to-parameter ratio = 11.0

checkCIF/PLATON results

No syntax errors found



Alert level C
            Value of measurement temperature given =   100.000
            Value of melting point given =     0.000
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C2     ...       1.53 Ang.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The rapidly expanding field of the crystal engineering (the design of crystalline materials) of polymeric coordination networks stems has recently attracted great interest because of their potential applications as zeolite-like materials for molecular selection, ion exchange, and catalysis, as well as in the variety of architectures and topologies (Kitagawa et al., 2004; Kirillov et al., 2008). The main strategy popularly used in this area is a building-block approach (Hoskins & Robson, 1990; Eddaoudi et al., 2001). 2,6-Pyridinedicarboxylic acid (H₂PDA) is an efficient ligand. Polymeric structure of PDA complexes with transition and lanthanide metals have been reported, in which PDA not only chelates but also bridges to form diversified structures with three coordination sites (Zhao et al., 2003; Choi et al., 2003; Ghosh et al., 2004; Xie et al., 2004). We report the synthesis, and crystal structures of one compound, [Cu(µ-2,6-PDA)(py)]_n, (1).

Molecular structure of (1) shows a slightly distorted octahedral coordination geometry. The equatorial sites are occupied by an NO₂ donor from the carboxylate groups at the pyridine-2,6-position of PDA (N2, O1, O1ⁱ) and one N atom from pyridine (N1). Two O atoms from two other neighboring PDA ligands occupy the axial sites (O2, O2ⁱ) at a distance of 2.761 Å (Fig. 1). The equatorial Cu—O and Cu—N bond lengths of are normal [Cu1—O1 = 2.0110 (18) Å, Cu1—O1ⁱ = 2.0110 (18) Å, Cu1—N2 = 1.896 (3) Å, Cu1—N1 = 1.944 (3) Å], which are within ranges reported in other copper complexes (Uçar et al., 2007; Manna et al., 2007; Gao et al., 2006). The pyridine is essentially planar with no deviation from planarity for pyridyl N1-atom. The C—C—C angles about the pyridyl ring are 118.2 (3) to 128.5 (2)°, indicating sp² hybridization. Two carboxylate O atoms (O2 and O2ⁱ) which are coordinated to the adjacent copper atom, have C—O distances [O2—C1 = 1.228 (3) Å, O1—C1 = 1.290 (3) Å] which are generally shorter than C—O distances, indicating the conjugation of the double bond after deprotonation. In this way, the PDA ligands bridge adjacent Cu atoms to form a [Cu(µ-2,6-PDC)(py)]n linear chains extending in the [001] direction (Fig. 2). The separations between the two Cu atom in the linear chains are 5.332 Å. The PDA ligand and pyridine are trans to each other (N2—Cu1—N1 = 180°). However, one-dimensional polymeric chains are connected in the solid state through weak C—H···O and π-π interactions. Weak C—H···O interactions that connects polymeric chains into two-dimensional network (Fig. 3). Contact distances for C—H···O interactions are 2.43–2.76 Å (Table 1). The weak π-π interactions are present in (1). Further, the importance of π-π stacking interactions between aromatic rings has widely been recognized in the intercalation of drugs with DNA especially in biological systems, which lie in the range 3.4–3.5 Å. The complex (1) exhibits intermolecular face-to-face π-π interactions [π-pyridyl/π-pyridyl ct/ct distance 3.9104 (13) Å; Fig. 4].

Related literature

For background information on coordination polymers, see: Kitagawa et al. (2004); Kirillov et al. (2008); Hoskins & Robson (1990); Eddaoudi et al. (2001). For related polymeric structures of PDA complexes, see, for example: Zhao et al. (2003); Choi et al. (2003); Ghosh et al. (2004); Xie et al. (2004). For related structures of Cu complexes, see: Uçar et al. (2007); Manna et al. (2007); Gao et al. (2006).

S2. Experimental

A mixture of [Cu(NO₃)₂.6H₂O] (0.466 g, 2 mmol), H₂PDA (0.167 g, 1 mmol), 2-Pyridine thiol(0.111 g, 1 mmol) was dissolved in a mixture of MeOH (5 ml) and water (5 mL) and add pyridine (in excess). The solution was stirred for 24 h at room temperature. Slowly, color of the solution changes from blue to dark green. The resulting solution was filtered and left at room temperature for two days, which resulted in blue needle crystals which are suitable for X-ray diffraction analysis (yield 0.184 g, 60%). Anal. Calc. for C₁₂H₈N₂O₄Cu: C 48.83, H 2.62, N 9.10%; found: C 47.65, H 2.56, N 9.30%.

S3. Refinement

All H atoms were added in their calculated positions (C—H = 0.95 Å) and were treated using appropriate riding models, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A view of the structure of (1), showing the atom-numbering scheme and the Cu coordination octahedra; displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Packing view of (1), showing linear chains along the [001] direction.
	Fig. 3. Packing view of (1), showing connectivity with other polymeric chains through weak C—H···O hydrogen bond interactions.
	Fig. 4. Packing view of (1), showing face-to-face π-π interactions.

catena-Poly[[(pyridine-κN)copper(II)]-µ₃-pyridine-2,6- dicarboxylato-κ³O²:O^2',N,O⁶:O^6']

Crystal data

[Cu(C7H3NO4)(C5H5N)]	F(000) = 620
Mr = 307.74	Dx = 1.912 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1607 reflections
a = 7.8042 (9) Å	θ = 3.0–25.3°
b = 13.6152 (17) Å	µ = 2.06 mm^−1
c = 10.0667 (12) Å	T = 100 K
β = 91.687 (4)°	Needle, blue
V = 1069.2 (2) Å^3	0.21 × 0.13 × 0.08 mm
Z = 4

Data collection

Bruker APEXII CCD area-detector diffractometer	981 independent reflections
Radiation source: fine-focus sealed tube	859 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
ϕ and ω scans	θmax = 25.3°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2007)	h = −9→8
Tmin = 0.671, Tmax = 0.848	k = −16→16
3530 measured reflections	l = −12→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.074	H-atom parameters not refined
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0347P)^2 + 1.5139P] where P = (Fo^2 + 2Fc^2)/3
981 reflections	(Δ/σ)max < 0.001
89 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.60 e Å^−3

Special details

Experimental. All H atoms were added in their calculated positions and were treated using appropriate riding models.

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
Cu1	0.5000	0.06463 (3)	0.2500	0.01055 (18)
O1	0.3461 (2)	0.04164 (13)	0.08928 (18)	0.0119 (4)
O2	0.2652 (2)	−0.07906 (13)	−0.05100 (19)	0.0137 (4)
N1	0.5000	0.2074 (2)	0.2500	0.0099 (7)
N2	0.5000	−0.0746 (2)	0.2500	0.0096 (7)
C1	0.3334 (3)	−0.04888 (19)	0.0526 (3)	0.0111 (6)
C2	0.4161 (3)	−0.1210 (2)	0.1514 (3)	0.0100 (6)
C3	0.4135 (3)	−0.2221 (2)	0.1484 (3)	0.0120 (6)
H3	0.3542	−0.2564	0.0789	0.014*
C4	0.5000	−0.2728 (3)	0.2500	0.0130 (8)
H4	0.5000	−0.3426	0.2500	0.016*
C5	0.5748 (3)	0.2583 (2)	0.3507 (3)	0.0124 (6)
H5	0.6286	0.2230	0.4218	0.015*
C6	0.5765 (4)	0.3594 (2)	0.3549 (3)	0.0154 (6)
H6	0.6290	0.3931	0.4281	0.018*
C7	0.5000	0.4112 (3)	0.2500	0.0159 (9)
H7	0.5000	0.4810	0.2500	0.019*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0144 (3)	0.0059 (3)	0.0109 (3)	0.000	−0.00649 (18)	0.000
O1	0.0151 (10)	0.0074 (10)	0.0129 (10)	−0.0014 (8)	−0.0066 (8)	0.0000 (8)
O2	0.0173 (10)	0.0117 (11)	0.0118 (10)	−0.0026 (8)	−0.0068 (8)	−0.0017 (8)
N1	0.0095 (16)	0.0095 (17)	0.0108 (17)	0.000	−0.0009 (13)	0.000
N2	0.0085 (16)	0.0102 (17)	0.0100 (16)	0.000	−0.0009 (13)	0.000
C1	0.0114 (14)	0.0106 (14)	0.0114 (15)	−0.0017 (11)	−0.0007 (11)	0.0004 (11)
C2	0.0080 (13)	0.0125 (15)	0.0095 (14)	−0.0020 (11)	−0.0011 (11)	−0.0023 (11)
C3	0.0122 (14)	0.0131 (15)	0.0108 (14)	−0.0006 (11)	−0.0019 (11)	−0.0018 (11)
C4	0.014 (2)	0.009 (2)	0.016 (2)	0.000	0.0001 (16)	0.000
C5	0.0124 (14)	0.0138 (15)	0.0110 (15)	0.0001 (11)	−0.0012 (11)	0.0007 (11)
C6	0.0163 (15)	0.0136 (15)	0.0163 (16)	−0.0035 (12)	0.0025 (12)	−0.0042 (12)
C7	0.016 (2)	0.009 (2)	0.023 (2)	0.000	0.0055 (17)	0.000

Geometric parameters (Å, º)

Cu1—N2	1.896 (3)	C2—C3	1.378 (4)
Cu1—N1	1.944 (3)	C3—C4	1.392 (3)
Cu1—O1	2.0110 (18)	C3—H3	0.9500
Cu1—O1^i	2.0110 (18)	C4—C3^i	1.392 (3)
O1—C1	1.290 (3)	C4—H4	0.9500
O2—C1	1.228 (3)	C5—C6	1.378 (4)
N1—C5^i	1.347 (3)	C5—H5	0.9500
N1—C5	1.347 (3)	C6—C7	1.390 (3)
N2—C2	1.332 (3)	C6—H6	0.9500
N2—C2^i	1.332 (3)	C7—C6^i	1.390 (3)
C1—C2	1.527 (4)	C7—H7	0.9500
N2—Cu1—N1	180.0	N2—C2—C1	111.7 (2)
N2—Cu1—O1	81.05 (5)	C3—C2—C1	128.5 (2)
N1—Cu1—O1	98.95 (5)	C2—C3—C4	118.2 (3)
N2—Cu1—O1^i	81.05 (5)	C2—C3—H3	120.9
N1—Cu1—O1^i	98.95 (5)	C4—C3—H3	120.9
O1—Cu1—O1^i	162.10 (10)	C3—C4—C3^i	120.6 (4)
C1—O1—Cu1	114.71 (16)	C3—C4—H4	119.7
C5^i—N1—C5	118.1 (3)	C3^i—C4—H4	119.7
C5^i—N1—Cu1	120.97 (16)	N1—C5—C6	122.8 (3)
C5—N1—Cu1	120.96 (16)	N1—C5—H5	118.6
C2—N2—C2^i	123.4 (3)	C6—C5—H5	118.6
C2—N2—Cu1	118.28 (16)	C5—C6—C7	118.7 (3)
C2^i—N2—Cu1	118.28 (16)	C5—C6—H6	120.7
O2—C1—O1	126.2 (2)	C7—C6—H6	120.7
O2—C1—C2	120.2 (2)	C6^i—C7—C6	119.0 (4)
O1—C1—C2	113.6 (2)	C6^i—C7—H7	120.5
N2—C2—C3	119.8 (3)	C6—C7—H7	120.5
N2—Cu1—O1—C1	−6.98 (18)	Cu1—N2—C2—C3	−179.96 (18)
N1—Cu1—O1—C1	173.02 (18)	C2^i—N2—C2—C1	−179.7 (2)
O1^i—Cu1—O1—C1	−6.98 (18)	Cu1—N2—C2—C1	0.3 (2)
O1—Cu1—N1—C5^i	−6.84 (14)	O2—C1—C2—N2	172.9 (2)
O1^i—Cu1—N1—C5^i	173.16 (14)	O1—C1—C2—N2	−6.2 (3)
O1—Cu1—N1—C5	173.16 (14)	O2—C1—C2—C3	−6.8 (4)
O1^i—Cu1—N1—C5	−6.84 (14)	O1—C1—C2—C3	174.1 (3)
O1—Cu1—N2—C2	3.29 (14)	N2—C2—C3—C4	−0.1 (4)
O1^i—Cu1—N2—C2	−176.71 (14)	C1—C2—C3—C4	179.6 (2)
O1—Cu1—N2—C2^i	−176.71 (14)	C2—C3—C4—C3^i	0.03 (18)
O1^i—Cu1—N2—C2^i	3.29 (14)	C5^i—N1—C5—C6	0.47 (19)
Cu1—O1—C1—O2	−170.2 (2)	Cu1—N1—C5—C6	−179.53 (19)
Cu1—O1—C1—C2	8.8 (3)	N1—C5—C6—C7	−0.9 (4)
C2^i—N2—C2—C3	0.04 (18)	C5—C6—C7—C6^i	0.44 (18)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O2^ii	0.95	2.44	3.187 (3)	135
C5—H5···O1^i	0.95	2.48	3.070 (3)	120
C6—H6···O1^iii	0.95	2.48	3.394 (3)	162

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