catena-Poly[[[diaqua­copper(II)]-μ-pyridine-2,4-dicarboxyl­ato-κ³N,O²:O⁴] 0.625-hydrate]

In the title compound, {[Cu(C₇H₃NO₄)(H₂O)₂]·0.625H₂O}_n, square-pyramidally coordinated Cu^II atoms with two cis-aqua ligands are linked into linear chains by bis-bridging pyridine-2,4-dicarboxyl­ate (PDC) dianions. The [Cu(PDC)(H₂O)₂]_n chains form ribbons through long-range Cu—O inter­actions; the ribbons aggregate into a three-dimensional network through hydrogen bonding. The two uncoordinated water mol­ecules of the asymmetric unit (one with partial occupancy) lie on different special positions of site symmetry 2.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.005 Å
• Disorder in solvent or counterion
• R factor = 0.041
• wR factor = 0.099
• Data-to-parameter ratio = 13.6

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF020_ALERT_1_A  _diffrn_standards_interval_count and
            _diffrn_standards_interval_time are missing. Number of measurements
            between standards or time (min) between standards.

Author Response: CCD detector used

Alert level B
PLAT420_ALERT_2_B D-H Without Acceptor       O1W    -   H1W    ...          ?

Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT302_ALERT_4_C Anion/Solvent Disorder .........................      13.00 Perc.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1W    ..  O2      ..       2.65 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         21

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

   2 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
   2 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Coordination polymers containing both pyridinedicarboxylate and organodiimine ligands have displayed intriguing structural morphologies and physical properties (Zhou et al., 2006). The title compound was prepared during an attempt to prepare a divalent copper coordination polymer containing both 2,4-pyridinedicarboxylate (PDC) and N,N'-di(4-pyridylmethyl)piperazine (bpmp) ligands.

The asymmetric unit of the title compound (Fig. 1) consists of a Cu^II ion, two aqua ligands, a single ligated PDC dianion, and waters molecule of crystallization located on crystallographic 2-fold axes (with 50% and 12.5% occupancies, respectively). The Cu^II ion manifests a Jahn–Teller distorted square pyramidal coordination, with cis aqua ligands occupying the axial position and one of the basal positions. The remainder of the basal coordination sites are occupied by an O atom from one PDC ligand, and an N donor and O donor from a second PDC ligand. The two O donors from the PDC ligands, from 2- and 4-carboxylate positions, are situated trans to each other.

Neighboring Cu^II ions are conjoined through exobidentate PDC ligands to form one-dimensional [Cu(H₂O)₂(PDC)]_n chains that propagate along the [011] crystal direction (Fig. 2), with a Cu—Cu distance measuring 8.883 (3) Å. These are aggregated into double chain motifs (Fig. 3) through long-range Cu—O interactions (2.841 (2) Å).

Double [Cu(H₂O)₂(PDC)]_n chains connect into pseudo layers, coincident with the bc crystal planes through hydrogen bonding between aqua ligands and unligated carboxylate O atoms. These subsequently stack into the pseudo three-dimensional crystal structure of the title compound through additional hydrogen bonding patterns involving the water molecules of crystallization (Fig. 4).

Related literature

For metal complexes of pyridinedicarboxylic acids, see: Pocic et al. (2005); Zhou et al. (2006).

S2. Experimental

Copper chloride dihydrate and 2,4-pyridinedicarboxylic acid (H₂PDC) were obtained commercially. N,N'-di(4-pyridylmethyl)piperazine (bpmp) was prepared via a published procedure (Pocic et al., 2005). Copper chloride dihydrate (0.044 g, 0.26 mmol) and H₂PDC (0.031 g, 0.19 mmol) were dissolved in 4 ml water in a glass vial. A solution of bpmp (0.050 g, 0.19 mmol) in 4 ml me thanol was carefully layered on top. Blue blocks of the title compound were deposited (0.047 g, 0.17 mmol, 89% yield) after one week at 293 K.

S3. Refinement

All H atoms bound to C atoms were placed in calculated positions, with C—H = 0.95 (2) Å and refined in riding mode with U_iso = 1.2U_eq(C). The H atoms bound to O in the aqua ligands and unligated water molecules were found via Fourier difference map, restrained with O—H = 0.85 (2) Å, and refined with U_iso =1.2U_eq(O).

Computing details

Data collection: COSMO (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: CrystalMaker (Palmer, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. Asymmetric unit of the title compound, showing 50% probability ellipsoids and atom numbering scheme. Hydrogen atoms positions are marked as gray sticks. The unligated water molecule is omitted.
	Fig. 2. A [Cu(H2O)2(PDC)]n chain motif within the title compound. Color codes: light-blue N, black C, red O, dark blue Cu.
	Fig. 3. A [Cu(H2O)2(PDC)]2n double chain motif within the title compound. Long Cu—O interactions are shown as dashed lines.
	Fig. 4. Partial stacking diagram of the pseudo three-dimensional structure of the title compound. Unligated water molecules are shown in orange.

catena-Poly[[[diaquacopper(II)]-µ-pyridine-2,4-dicarboxylato- κ³N,O²:O⁴] 0.625-hydrate]

Crystal data

[Cu(C7H3NO4)(H2O)2]·0.625H2O	Dx = 2.006 Mg m^−3
Mr = 275.94	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnna	Cell parameters from 7418 reflections
a = 20.324 (4) Å	θ = 2.0–28.3°
b = 12.057 (2) Å	µ = 2.41 mm^−1
c = 7.4706 (16) Å	T = 173 K
V = 1830.7 (6) Å^3	Block, blue
Z = 8	0.25 × 0.25 × 0.20 mm
F(000) = 1114

Data collection

Bruker APEXII diffractometer	2152 independent reflections
Radiation source: fine-focus sealed tube	1517 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ϕ and ω scans	θmax = 28.3°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −16→26
Tmin = 0.520, Tmax = 0.618	k = −10→15
7418 measured reflections	l = −6→9

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.099	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0426P)^2 + 0.2838P] where P = (Fo^2 + 2Fc^2)/3
2152 reflections	(Δ/σ)max = 0.001
158 parameters	Δρmax = 0.68 e Å^−3
21 restraints	Δρmin = −0.69 e Å^−3

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	Occ. (<1)
Cu1	0.631799 (18)	0.45906 (4)	0.18172 (6)	0.01542 (15)
O1	0.67326 (11)	0.7225 (2)	0.4821 (3)	0.0251 (7)
O1W	0.7500	0.5000	−0.3147 (6)	0.104 (3)
H1W	0.7590	0.5513	−0.3903	0.124*
O2W	0.7243 (11)	0.2500	−0.2500	0.108 (10)	0.25
H2W	0.7513	0.2379	−0.1577	0.130*	0.25
O2	0.68258 (10)	0.5671 (2)	0.3219 (3)	0.0174 (6)
O3	0.42732 (10)	0.8454 (2)	0.5840 (3)	0.0166 (6)
O4	0.35590 (11)	0.7053 (2)	0.5432 (4)	0.0320 (8)
O5	0.64138 (12)	0.5631 (2)	−0.0813 (4)	0.0231 (7)
H5A	0.6535 (18)	0.6282 (18)	−0.066 (5)	0.028*
H5B	0.6750 (13)	0.560 (3)	−0.142 (4)	0.028*
O6	0.71189 (11)	0.3848 (2)	0.1122 (4)	0.0208 (6)
H6A	0.7049 (18)	0.3176 (17)	0.106 (5)	0.025*
H6B	0.7394 (14)	0.371 (3)	0.188 (4)	0.025*
N1	0.55748 (12)	0.5464 (2)	0.2784 (4)	0.0128 (7)
C1	0.57573 (15)	0.6319 (3)	0.3852 (5)	0.0129 (8)
C2	0.53100 (15)	0.7009 (3)	0.4690 (5)	0.0136 (8)
H2	0.5454	0.7614	0.5407	0.016*
C3	0.46437 (15)	0.6796 (3)	0.4454 (5)	0.0130 (8)
C4	0.44555 (15)	0.5921 (3)	0.3370 (4)	0.0163 (8)
H4	0.4003	0.5766	0.3188	0.020*
C5	0.49278 (15)	0.5276 (3)	0.2556 (5)	0.0154 (8)
H5	0.4793	0.4679	0.1808	0.018*
C6	0.64987 (15)	0.6440 (3)	0.4010 (5)	0.0152 (8)
C7	0.41055 (15)	0.7489 (3)	0.5317 (5)	0.0176 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.01020 (19)	0.0141 (3)	0.0220 (3)	−0.00002 (17)	−0.00034 (17)	−0.0044 (2)
O1	0.0160 (11)	0.0209 (16)	0.0385 (17)	−0.0024 (11)	−0.0026 (11)	−0.0116 (14)
O1W	0.096 (4)	0.190 (7)	0.024 (3)	0.102 (5)	0.000	0.000
O2W	0.095 (18)	0.17 (3)	0.057 (15)	0.000	0.000	−0.005 (18)
O2	0.0103 (10)	0.0161 (15)	0.0258 (15)	0.0003 (9)	0.0015 (10)	−0.0046 (13)
O3	0.0138 (11)	0.0137 (15)	0.0222 (14)	0.0014 (10)	0.0023 (10)	−0.0046 (13)
O4	0.0158 (13)	0.0252 (17)	0.055 (2)	−0.0062 (11)	0.0115 (12)	−0.0181 (16)
O5	0.0194 (13)	0.0228 (17)	0.0270 (17)	−0.0053 (11)	0.0009 (11)	−0.0024 (15)
O6	0.0116 (11)	0.0175 (16)	0.0332 (17)	0.0034 (11)	−0.0046 (11)	−0.0050 (15)
N1	0.0119 (12)	0.0108 (17)	0.0157 (17)	0.0004 (11)	0.0002 (11)	−0.0010 (14)
C1	0.0133 (14)	0.011 (2)	0.0141 (19)	−0.0028 (14)	0.0008 (13)	0.0007 (17)
C2	0.0163 (15)	0.009 (2)	0.016 (2)	−0.0020 (13)	0.0008 (14)	−0.0042 (16)
C3	0.0148 (15)	0.010 (2)	0.014 (2)	0.0003 (13)	0.0032 (13)	0.0028 (16)
C4	0.0128 (15)	0.014 (2)	0.022 (2)	0.0014 (14)	−0.0013 (14)	−0.0012 (18)
C5	0.0155 (15)	0.014 (2)	0.0172 (19)	0.0002 (14)	−0.0013 (14)	−0.0052 (17)
C6	0.0127 (15)	0.013 (2)	0.020 (2)	−0.0002 (14)	−0.0018 (14)	0.0009 (19)
C7	0.0158 (16)	0.017 (2)	0.020 (2)	0.0030 (15)	0.0016 (14)	−0.0009 (19)

Geometric parameters (Å, º)

Cu1—O6	1.931 (2)	O6—H6A	0.824 (18)
Cu1—O2	1.963 (2)	O6—H6B	0.815 (18)
Cu1—O3^i	1.964 (2)	N1—C5	1.348 (4)
Cu1—N1	1.980 (3)	N1—C1	1.353 (4)
Cu1—O5	2.339 (3)	C1—C2	1.383 (4)
O1—C6	1.219 (4)	C1—C6	1.522 (4)
O1W—H1W	0.8563	C2—C3	1.392 (4)
O2W—H2W	0.8920	C2—H2	0.9500
O2—C6	1.285 (4)	C3—C4	1.382 (5)
O3—C7	1.273 (4)	C3—C7	1.521 (4)
O4—C7	1.234 (4)	C4—C5	1.378 (4)
O5—H5A	0.831 (18)	C4—H4	0.9500
O5—H5B	0.822 (18)	C5—H5	0.9500
O6—Cu1—O2	90.46 (10)	N1—C1—C2	122.8 (3)
O6—Cu1—O3^i	95.30 (11)	N1—C1—C6	113.0 (3)
O2—Cu1—O3^i	169.33 (10)	C2—C1—C6	124.1 (3)
O6—Cu1—N1	171.84 (11)	C1—C2—C3	118.3 (3)
O2—Cu1—N1	81.58 (10)	C1—C2—H2	120.8
O3^i—Cu1—N1	92.30 (10)	C3—C2—H2	120.8
O6—Cu1—O5	87.36 (11)	C4—C3—C2	119.0 (3)
O2—Cu1—O5	92.78 (9)	C4—C3—C7	117.8 (3)
O3^i—Cu1—O5	96.48 (10)	C2—C3—C7	123.2 (3)
N1—Cu1—O5	94.86 (11)	C5—C4—C3	119.6 (3)
C6—O2—Cu1	116.7 (2)	C5—C4—H4	120.2
C7—O3—Cu1^ii	125.9 (2)	C3—C4—H4	120.2
Cu1—O5—H5A	115 (3)	N1—C5—C4	122.1 (3)
Cu1—O5—H5B	120 (3)	N1—C5—H5	118.9
H5A—O5—H5B	83 (3)	C4—C5—H5	118.9
Cu1—O6—H6A	109 (3)	O1—C6—O2	125.8 (3)
Cu1—O6—H6B	119 (3)	O1—C6—C1	120.0 (3)
H6A—O6—H6B	87 (3)	O2—C6—C1	114.2 (3)
C5—N1—C1	118.1 (3)	O4—C7—O3	127.6 (3)
C5—N1—Cu1	127.7 (2)	O4—C7—C3	116.4 (3)
C1—N1—Cu1	114.1 (2)	O3—C7—C3	116.0 (3)
O6—Cu1—O2—C6	178.6 (3)	C2—C3—C4—C5	0.4 (5)
O3^i—Cu1—O2—C6	−58.7 (7)	C7—C3—C4—C5	179.7 (3)
N1—Cu1—O2—C6	−3.2 (3)	C1—N1—C5—C4	−0.1 (5)
O5—Cu1—O2—C6	91.2 (3)	Cu1—N1—C5—C4	177.0 (3)
O2—Cu1—N1—C5	−176.9 (3)	C3—C4—C5—N1	0.3 (6)
O3^i—Cu1—N1—C5	−5.7 (3)	Cu1—O2—C6—O1	−174.1 (3)
O5—Cu1—N1—C5	91.1 (3)	Cu1—O2—C6—C1	5.1 (4)
O2—Cu1—N1—C1	0.3 (2)	N1—C1—C6—O1	174.5 (3)
O3^i—Cu1—N1—C1	171.5 (2)	C2—C1—C6—O1	−4.9 (6)
O5—Cu1—N1—C1	−91.7 (2)	N1—C1—C6—O2	−4.8 (5)
C5—N1—C1—C2	−0.9 (5)	C2—C1—C6—O2	175.8 (3)
Cu1—N1—C1—C2	−178.4 (3)	Cu1^ii—O3—C7—O4	−5.5 (6)
C5—N1—C1—C6	179.7 (3)	Cu1^ii—O3—C7—C3	174.6 (2)
Cu1—N1—C1—C6	2.2 (4)	C4—C3—C7—O4	20.4 (5)
N1—C1—C2—C3	1.6 (5)	C2—C3—C7—O4	−160.3 (4)
C6—C1—C2—C3	−179.1 (3)	C4—C3—C7—O3	−159.7 (3)
C1—C2—C3—C4	−1.3 (5)	C2—C3—C7—O3	19.6 (5)
C1—C2—C3—C7	179.4 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W···O2^iii	0.86	2.65	3.145 (5)	117
O2W—H2W···O1^iv	0.89	2.02	2.904 (17)	168
O5—H5A···O1^v	0.83 (2)	1.95 (2)	2.765 (4)	168 (4)
O5—H5B···O1W	0.82 (2)	2.12 (2)	2.914 (4)	162 (4)
O6—H6A···O4^i	0.82 (2)	1.89 (2)	2.618 (4)	146 (4)
O6—H6B···O2^vi	0.82 (2)	2.02 (2)	2.719 (3)	144 (4)

Symmetry codes: (i) −x+1, y−1/2, z−1/2; (iii) x, y, z−1; (iv) −x+3/2, y−1/2, −z+1/2; (v) x, −y+3/2, −z+1/2; (vi) −x+3/2, −y+1, z.