Aqua­(6,6′-oxydipicolinato-κ²O,N,N′,O′)copper(II)

In the title complex, [Cu(C₁₂H₆N₂O₅)(H₂O)], the Cu^II ion is in a slightly distorted square-pyramidal coordination environment with two N and two O atoms from a 6,6′-oxydipicolinate ligand occupying the basal plane and a water ligand in the apical site. The dihedral angle between the two pyridine rings is 5.51 (6)°. In the crystal structure, inter­molecular O—H...O hydrogen bonds link mol­ecules into a two-dimensional network. In addition, weak inter­molecular C—H...O and C=O(lone pair)...π(ring) inter­actions, with O...ring-centroid distances of 3.697 (4) and 3.094 (4) Å, provide additional stabilization.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.032
• wR factor = 0.110
• Data-to-parameter ratio = 10.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C2     ...       1.53 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.595         10

Alert level G
PLAT128_ALERT_4_G Non-standard setting of Space-group P21/c   ....      P21/n

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   1 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
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

Picolinic acid compounds play an vital role in the development of coordination chemistry related to catalysis, magnetism and molecular architectures (Mann et al., 1992). As part of our studies on the synthesis and characterization of these types of compounds, we report here the synthesis and crystal structure of the title compound (I).

The molecular structure of the title compound (I) is shown in Fig. 1. The Cu^II ion is in a slightly distorted square-pyramidal coordination environment with two N and two O atoms from a 6,6'-oxydipicolinato ligand occupying the basal plane and one water ligand in the apical site. The dihedral angle between the two pyridine rings is 5.51 (6)°. The delocalization of electrons within the carboxylate groups is reflected in the C═O lengths. In the crystal structure, there are intermolecular O—H···O hydrogen bonds involving the carboxyl oxygen atoms and coordinated water molecules (Fig. 2) forming a two-dimensional network (see Table 1 for hydrogen bond geometries). In addition to weak intermolecular C-H···O interactions, further stabilization appears to be provided by weak C=O(lone pair)···π(ring) stacking interactions (Choudhury et al., 2008). The relevant distances are C12—O4···Cg1ⁱ = 3.697 (4) Å, Cg1 is the centroid of the ring defined by the atoms N1/C7-C11 [symmetry code: (i) -x, -y, 2-z] and the angle C12—O4···Cg1ⁱ is 98.95 (34)°; C1—O2···Cg2ⁱⁱ = 3.094 (4) Å, Cg2 is the centroid of the ring defined by the atoms N2/C2-C6 [symmetry code: (ii) 0.5+x, 0.5-y, 0.5+z] and the angle C1—O2···Cg2ⁱⁱ is 115.48 (4)° (see Fig. 3).

Related literature

For information on similar types of intermolecular interactions as found in the title compound, see: Choudhury et al. (2008). For the applications of picolinic acid compounds, see: Mann et al. (1992).

S2. Experimental

All reagents were available commercially and were used without further purification. 6,6'-Oxydipicolinic acid (260 mg) was added to 1 mmol (132 mg) of CuCl₂ in 10 ml of water. The suspension was stirred for 4 h and filtered. After leaving the filtrate in air for one week, blue block-shaped crystals of (I) were formed. The crystals were isolated, washed with water three times and dried in a vacuum desicator using silica gel (Yield 75%). Elemental analysis: found C, 42.05; H, 2.96; N, 8.18%; calc. for C₁₂H₈CuN₂O₆; C, 42.17; H, 2.95; N, 8.20%.

S3. Refinement

H atoms bonded to C atoms were positioned geometrically and refined using a riding-model approximation with C–H = 0.93 Å, and U_iso(H) = 1.2U_eq(C). H atoms bonded to O atoms were found in difference Fourier maps and included as riding with O—H = 0.85Å and U_iso(H) = 1.2U_eq(O).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of (I) showing 50% proability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. Part of the crystal structure of (I) showing hydrogen bonds as dashed lines.
	Fig. 3. Part of the crystal structure of (I) showing C=O(lone pair)···π(ring) stacking interactions as dashed lines.

Aqua(6,6'-oxydipicolinato-κ²O,N,N',O')copper(II)

Crystal data

[Cu(C12H6N2O5)(H2O)]	F(000) = 684
Mr = 339.74	Dx = 1.915 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2501 reflections
a = 7.2487 (16) Å	θ = 2.8–27.5°
b = 21.055 (4) Å	µ = 1.89 mm^−1
c = 8.2269 (17) Å	T = 296 K
β = 110.201 (9)°	Block, blue
V = 1178.4 (4) Å^3	0.40 × 0.35 × 0.30 mm
Z = 4

Data collection

Siemens SMART CCD diffractometer	2074 independent reflections
Radiation source: fine-focus sealed tube	1806 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ϕ and ω scans	θmax = 25.0°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.519, Tmax = 0.602	k = −24→24
6790 measured reflections	l = −9→8

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H-atom parameters constrained
S = 1.18	w = 1/[σ^2(Fo^2) + (0.0671P)^2 + 0.1209P] where P = (Fo^2 + 2Fc^2)/3
2074 reflections	(Δ/σ)max < 0.001
190 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.37 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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	0.33165 (5)	0.109980 (17)	0.96148 (4)	0.02725 (18)
O3	0.2907 (3)	0.05841 (10)	1.1417 (3)	0.0327 (5)
N2	0.4163 (4)	0.14875 (12)	0.7848 (3)	0.0265 (6)
O1	0.4318 (3)	0.18774 (11)	1.0899 (3)	0.0336 (5)
O5	0.3272 (4)	0.06644 (11)	0.5777 (3)	0.0368 (6)
N1	0.2837 (4)	0.03042 (12)	0.8315 (3)	0.0254 (6)
O4	0.2158 (4)	−0.04040 (11)	1.1935 (3)	0.0409 (6)
O2	0.5275 (4)	0.28511 (11)	1.0481 (3)	0.0410 (6)
C12	0.2463 (4)	0.00062 (15)	1.1003 (4)	0.0268 (7)
C1	0.4833 (5)	0.23022 (15)	1.0031 (4)	0.0297 (7)
O6	0.0171 (3)	0.14739 (11)	0.8390 (3)	0.0382 (6)
H6A	−0.0120	0.1623	0.7373	0.046*
H6B	−0.0521	0.1144	0.8010	0.046*
C2	0.4850 (5)	0.20891 (14)	0.8261 (4)	0.0284 (7)
C5	0.4587 (5)	0.15934 (17)	0.5117 (4)	0.0342 (8)
H5	0.4473	0.1419	0.4048	0.041*
C11	0.2346 (4)	−0.01770 (15)	0.9187 (4)	0.0258 (7)
C10	0.1814 (5)	−0.07640 (16)	0.8462 (4)	0.0348 (8)
H10	0.1481	−0.1089	0.9075	0.042*
C6	0.4036 (5)	0.12555 (15)	0.6311 (4)	0.0298 (7)
C8	0.2272 (5)	−0.03744 (16)	0.5894 (4)	0.0358 (8)
H8	0.2241	−0.0430	0.4763	0.043*
C7	0.2808 (5)	0.02011 (15)	0.6721 (4)	0.0280 (7)
C9	0.1787 (5)	−0.08608 (16)	0.6763 (4)	0.0374 (8)
H9	0.1441	−0.1255	0.6235	0.045*
C3	0.5440 (5)	0.24521 (16)	0.7162 (4)	0.0366 (8)
H3	0.5919	0.2861	0.7470	0.044*
C4	0.5311 (5)	0.21967 (17)	0.5561 (5)	0.0407 (9)
H4	0.5715	0.2435	0.4793	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0409 (3)	0.0226 (3)	0.0216 (3)	−0.00293 (15)	0.01511 (19)	−0.00212 (14)
O3	0.0481 (14)	0.0300 (13)	0.0229 (11)	−0.0044 (10)	0.0161 (10)	−0.0017 (9)
N2	0.0309 (14)	0.0253 (14)	0.0242 (13)	0.0005 (11)	0.0105 (10)	0.0002 (11)
O1	0.0470 (14)	0.0288 (12)	0.0267 (11)	−0.0051 (10)	0.0150 (10)	−0.0053 (9)
O5	0.0589 (16)	0.0326 (13)	0.0237 (11)	−0.0090 (11)	0.0203 (11)	−0.0052 (10)
N1	0.0327 (14)	0.0225 (13)	0.0220 (12)	−0.0009 (11)	0.0108 (10)	−0.0010 (10)
O4	0.0594 (16)	0.0381 (14)	0.0303 (12)	−0.0093 (12)	0.0219 (11)	0.0034 (11)
O2	0.0495 (15)	0.0263 (13)	0.0471 (15)	−0.0071 (10)	0.0166 (12)	−0.0104 (11)
C12	0.0283 (16)	0.0302 (18)	0.0215 (15)	0.0000 (13)	0.0082 (13)	0.0033 (13)
C1	0.0275 (16)	0.0285 (19)	0.0323 (16)	0.0031 (13)	0.0094 (13)	−0.0018 (14)
O6	0.0378 (13)	0.0339 (13)	0.0400 (13)	0.0015 (10)	0.0098 (11)	0.0019 (11)
C2	0.0286 (16)	0.0233 (16)	0.0310 (16)	−0.0001 (13)	0.0075 (13)	0.0014 (13)
C5	0.0361 (18)	0.040 (2)	0.0298 (17)	0.0017 (14)	0.0164 (14)	0.0037 (14)
C11	0.0289 (16)	0.0250 (16)	0.0234 (15)	0.0026 (12)	0.0087 (12)	0.0014 (12)
C10	0.048 (2)	0.0268 (18)	0.0324 (18)	−0.0054 (14)	0.0167 (15)	−0.0001 (14)
C6	0.0361 (18)	0.0305 (18)	0.0246 (16)	0.0025 (14)	0.0130 (13)	0.0022 (13)
C8	0.046 (2)	0.036 (2)	0.0277 (16)	−0.0008 (15)	0.0161 (15)	−0.0095 (15)
C7	0.0348 (17)	0.0279 (17)	0.0227 (15)	0.0012 (13)	0.0117 (13)	−0.0001 (13)
C9	0.050 (2)	0.0285 (18)	0.0346 (18)	−0.0074 (16)	0.0160 (16)	−0.0114 (15)
C3	0.0374 (19)	0.0310 (18)	0.042 (2)	−0.0050 (15)	0.0142 (15)	0.0034 (16)
C4	0.043 (2)	0.042 (2)	0.042 (2)	−0.0028 (16)	0.0217 (16)	0.0123 (17)

Geometric parameters (Å, º)

Cu1—O3	1.942 (2)	O6—H6A	0.8500
Cu1—N2	1.942 (3)	O6—H6B	0.8501
Cu1—O1	1.948 (2)	C2—C3	1.361 (5)
Cu1—N1	1.953 (2)	C5—C4	1.375 (5)
Cu1—O6	2.290 (2)	C5—C6	1.379 (4)
O3—C12	1.275 (4)	C5—H5	0.9300
N2—C6	1.328 (4)	C11—C10	1.368 (5)
N2—C2	1.361 (4)	C10—C9	1.406 (5)
O1—C1	1.278 (4)	C10—H10	0.9300
O5—C7	1.359 (4)	C8—C9	1.363 (5)
O5—C6	1.371 (4)	C8—C7	1.378 (5)
N1—C7	1.323 (4)	C8—H8	0.9300
N1—C11	1.358 (4)	C9—H9	0.9300
O4—C12	1.225 (4)	C3—C4	1.395 (5)
O2—C1	1.222 (4)	C3—H3	0.9300
C12—C11	1.517 (4)	C4—H4	0.9300
C1—C2	1.528 (4)
O3—Cu1—N2	167.91 (10)	N2—C2—C1	112.9 (3)
O3—Cu1—O1	100.51 (9)	C3—C2—C1	125.2 (3)
N2—Cu1—O1	84.13 (10)	C4—C5—C6	117.7 (3)
O3—Cu1—N1	83.87 (9)	C4—C5—H5	121.1
N2—Cu1—N1	89.62 (10)	C6—C5—H5	121.1
O1—Cu1—N1	168.68 (10)	N1—C11—C10	122.0 (3)
O3—Cu1—O6	97.86 (10)	N1—C11—C12	113.2 (3)
N2—Cu1—O6	92.86 (10)	C10—C11—C12	124.8 (3)
O1—Cu1—O6	94.45 (9)	C11—C10—C9	118.0 (3)
N1—Cu1—O6	95.29 (10)	C11—C10—H10	121.0
C12—O3—Cu1	114.87 (19)	C9—C10—H10	121.0
C6—N2—C2	118.7 (3)	N2—C6—O5	121.8 (3)
C6—N2—Cu1	128.4 (2)	N2—C6—C5	123.1 (3)
C2—N2—Cu1	112.8 (2)	O5—C6—C5	115.1 (3)
C1—O1—Cu1	114.29 (19)	C9—C8—C7	118.8 (3)
C7—O5—C6	128.3 (2)	C9—C8—H8	120.6
C7—N1—C11	118.9 (3)	C7—C8—H8	120.6
C7—N1—Cu1	128.5 (2)	N1—C7—O5	121.8 (3)
C11—N1—Cu1	112.4 (2)	N1—C7—C8	122.6 (3)
O4—C12—O3	126.1 (3)	O5—C7—C8	115.6 (3)
O4—C12—C11	118.5 (3)	C8—C9—C10	119.7 (3)
O3—C12—C11	115.4 (3)	C8—C9—H9	120.2
O2—C1—O1	126.1 (3)	C10—C9—H9	120.2
O2—C1—C2	118.6 (3)	C2—C3—C4	118.5 (3)
O1—C1—C2	115.3 (3)	C2—C3—H3	120.8
Cu1—O6—H6A	115.6	C4—C3—H3	120.8
Cu1—O6—H6B	104.6	C5—C4—C3	120.1 (3)
H6A—O6—H6B	91.5	C5—C4—H4	119.9
N2—C2—C3	121.9 (3)	C3—C4—H4	119.9

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···O4^i	0.93	2.31	3.229 (4)	171
C9—H9···O2^ii	0.93	2.42	3.331 (4)	165
C4—H4···O6^iii	0.93	2.54	3.303 (4)	140
O6—H6B···O4^iv	0.85	1.97	2.772 (3)	157
O6—H6A···O2^v	0.85	2.01	2.807 (3)	156

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