Diaqua­bis(5-carb­oxy-2-methyl-1H-imidazole-4-carboxyl­ato-κ²N³,O⁴)cobalt(II)

The Co atom in the title compound, [Co(C₆H₅N₂O₄)₂(H₂O)₂], is located on an inversion centre and exhibits a distorted octa­hedral geometry. It is trans coordinated by two N,O-bidentate 5-carb­oxy-2-methyl-1H-imidazole-4-carboxyl­ate monoanionic ligands with two water mol­ecules in the axial positions. Each ligand is stabilized by a strong, almost symmetrical, hydrogen bond. Inter­molecular N—H...O hydrogen bonds link the mol­ecules into layers, which are further linked into a three-dimensional supra­molecular framework through O—H...O hydrogen-bonding inter­actions involving the water mol­ecules.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.028
• wR factor = 0.084
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.48

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Co1         (2)       1.87
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 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
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Recently, our group (Nie et al., 2007) described the structure of diaquabis [2-methyl-1H-imidazole-4,5-dicarboxylato(1-)]cadmium (II) as a three-dimensional network of [Cd(H₂MIA)₂(H₂O)₂] molecules held together by hydrogen-bonding interactions. The present centrosymmetric Co complex is similiar to the Cd complex, but there are some differences in their structures.

The molecule of (I) is a discrete neutral monomer, in which the asymmetric unit contains one-half of the [Co(H₂MIA)₂(H₂O)₂] formula unit. The Co atom lies on a crystallographic inversion center and has a slightly distorted octahedral geometry. Two coordinated water molecules occupy the apical positions. The equatorial plane contains two bidentate 2-methyl-1H-imidazole-4,5-dicarboxylic acid monoanionic ligands which display a strong intramolecular O—H···O symmetrical hydrogen bond with a short O···O distance of 2.462 (2) Å (Fig. 1; Table 1). Similar strong intramolecular hydrogen bondings has been already reported with this ligand (Liu et al., 2004; Liu et al., 2006).

Owing to the location of the Co on an inversion center, the two chelate rings are coplanar, with a mean deviation 0.042 (2) Å, whereas in the Cd complex, the two chelate rings are shifted with a distance between the two planes of 0.5615 Å.. In the Cd complex, N—H···O hydrogen bonds link the molecules into chains which are further linked to a three-dimensional supramolecular framework via O—H···O hydrogen bonds whereas in the title complex, N—H···O hydrogen bonds (Table 1) link the molecules into a two-dimensional layers (Fig. 2). These layers are further linked through O—H···O (Table 1) involving the coordinated water O atoms and two carboxy O atoms to form a three-dimensional supramolecular framework. The Cd complex crystallizes in Monoclinic, space group P 2₁/c whereas the Co complex belongs to the orthorhombic, Pbca space group.

Related literature

For related literature, see: Nie et al. (2007); Liu et al. (2004); Liu et al. (2006).

S2. Experimental

Preparation of [Co(H₂MIA)₂(H₂O)₂]: A heavy-walled prex tube containing a mixture of Co(OAc)₂.6H₂O (0.0285 g, 0.1 mmol), 2-methyl -1H-imidazole-4,5-dicarboxylic acid (0.034 g, 0.2 mmol), 0.65 mol/L NaOH solutions (0.3 ml) and H₂O (2 ml) was frozen in liquid N₂, sealed under vacuum and placed inside an oven at 150 °C. The red single crystals (I) suitable for X-ray analysis were then obtained after heating of 3 d. Yield: 0.026 g, 60%. Analysis, calculated for C12H14CoN4O10 (433.20): C 33.27, H 3.26, N 12.93%; found: C 33.12, H 3.36, N 12.90%.

S3. Refinement

All H atoms attached to C atoms and N atom were fixed geometrically and treated as riding with C—H = 0.93 Å (aromatic) or 0.96 Å (methyl) and N—H = 0.86 Å with U_iso(H) = xU_eq(C or N) where x=1.2 for C(aromatic) or N and 1.5 for methyl group.. H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O—H= 0.85 (1)Å and H···H= 1.39 (2) Å) with U_iso(H) = 1.5U_eq(O).In the final stage of refinement they coordinates were fixed.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. Molecular view of the Co(II) complex (I) with the atom-labelling scheme. Ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. [Symmetry code: (i) 1 - x, 1 - y, 1 - z]
	Fig. 2. Partial packing view of (I), showing a two-dimensional sheet viewed down the a axis. H-bonds are shown as dashed lines.

Diaqua(5-carboxy-2-methyl-1H-imidazole-4-carboxylato-\k²N³,O⁴)cobalt(II)

Crystal data

[Co(C6H5N2O4)2(H2O)2]	F(000) = 884
Mr = 433.20	Dx = 1.805 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3494 reflections
a = 6.8261 (8) Å	θ = 2.9–28.1°
b = 13.9705 (16) Å	µ = 1.14 mm^−1
c = 16.7173 (19) Å	T = 291 K
V = 1594.2 (3) Å^3	Block, red
Z = 4	0.38 × 0.18 × 0.16 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1825 independent reflections
Radiation source: fine-focus sealed tube	1459 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
φ and ω scans	θmax = 27.5°, θmin = 2.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.673, Tmax = 0.839	k = −17→18
10909 measured reflections	l = −20→21

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.084	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0453P)^2 + 0.4264P] where P = (Fo^2 + 2Fc^2)/3
1825 reflections	(Δ/σ)max < 0.001
128 parameters	Δρmax = 0.33 e Å^−3
3 restraints	Δρmin = −0.33 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
Co1	0.5000	0.5000	0.5000	0.02327 (13)
O1	0.4610 (2)	0.37350 (9)	0.87496 (7)	0.0384 (3)
O2	0.5322 (2)	0.52489 (10)	0.84444 (8)	0.0353 (3)
O3	0.5701 (2)	0.62758 (8)	0.72576 (7)	0.0354 (3)
H3	0.545 (3)	0.5850 (17)	0.7866 (15)	0.053*
O4	0.5556 (2)	0.60690 (8)	0.59313 (7)	0.0321 (3)
O5	0.7904 (2)	0.46448 (11)	0.49466 (6)	0.0356 (3)
H1W	0.8536	0.4646	0.4530	0.053*
H2W	0.8482	0.4340	0.5309	0.053*
N1	0.47986 (19)	0.41778 (10)	0.60525 (8)	0.0234 (3)
N2	0.4548 (2)	0.32451 (10)	0.71031 (8)	0.0273 (3)
H2	0.4385	0.2738	0.7387	0.033*
C1	0.4181 (4)	0.24506 (13)	0.57651 (11)	0.0446 (5)
H1A	0.4148	0.2657	0.5218	0.067*
H1B	0.2958	0.2152	0.5900	0.067*
H1C	0.5228	0.2000	0.5837	0.067*
C2	0.4504 (3)	0.32885 (12)	0.62924 (10)	0.0269 (4)
C3	0.4899 (2)	0.41492 (12)	0.73939 (10)	0.0232 (3)
C4	0.5065 (2)	0.47207 (13)	0.67325 (10)	0.0228 (3)
C5	0.4943 (2)	0.43642 (13)	0.82581 (10)	0.0268 (4)
C6	0.5460 (2)	0.57575 (12)	0.66241 (10)	0.0248 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0353 (2)	0.0211 (2)	0.0134 (2)	−0.00068 (12)	−0.00038 (11)	0.00064 (11)
O1	0.0641 (9)	0.0341 (7)	0.0171 (6)	0.0043 (6)	0.0036 (6)	0.0033 (5)
O2	0.0582 (9)	0.0314 (7)	0.0163 (6)	0.0004 (6)	−0.0036 (5)	−0.0031 (5)
O3	0.0631 (9)	0.0227 (6)	0.0205 (6)	−0.0040 (6)	−0.0022 (6)	−0.0050 (5)
O4	0.0538 (8)	0.0232 (6)	0.0194 (6)	−0.0038 (6)	−0.0007 (5)	0.0001 (5)
O5	0.0367 (7)	0.0506 (8)	0.0195 (6)	0.0070 (7)	0.0023 (5)	0.0063 (5)
N1	0.0350 (7)	0.0204 (7)	0.0148 (7)	−0.0014 (5)	−0.0013 (5)	−0.0008 (5)
N2	0.0412 (8)	0.0223 (7)	0.0186 (7)	−0.0018 (6)	0.0003 (6)	0.0027 (5)
C1	0.0819 (15)	0.0254 (9)	0.0265 (10)	−0.0102 (10)	−0.0024 (10)	−0.0040 (7)
C2	0.0389 (9)	0.0228 (8)	0.0189 (8)	−0.0005 (7)	−0.0004 (7)	−0.0001 (6)
C3	0.0296 (8)	0.0220 (8)	0.0180 (8)	0.0015 (6)	−0.0002 (6)	−0.0005 (6)
C4	0.0304 (8)	0.0215 (8)	0.0166 (8)	0.0004 (6)	−0.0004 (6)	−0.0015 (6)
C5	0.0328 (9)	0.0292 (10)	0.0185 (9)	0.0053 (6)	−0.0004 (6)	−0.0004 (7)
C6	0.0344 (8)	0.0216 (8)	0.0186 (8)	0.0010 (6)	−0.0007 (6)	−0.0019 (6)

Geometric parameters (Å, º)

Co1—O5	2.0453 (14)	O5—H2W	0.8386
Co1—O5^i	2.0453 (14)	N1—C2	1.321 (2)
Co1—N1^i	2.1057 (14)	N1—C4	1.379 (2)
Co1—N1	2.1057 (14)	N2—C2	1.357 (2)
Co1—O4^i	2.1904 (12)	N2—C3	1.374 (2)
Co1—O4	2.1904 (12)	N2—H2	0.8600
O1—C5	1.225 (2)	C1—C2	1.482 (2)
O2—C5	1.301 (2)	C1—H1A	0.9600
O2—H3	1.28 (2)	C1—H1B	0.9600
O3—C6	1.2933 (19)	C1—H1C	0.9600
O3—H3	1.19 (2)	C3—C4	1.368 (2)
O4—C6	1.239 (2)	C3—C5	1.476 (2)
O5—H1W	0.8190	C4—C6	1.485 (2)
O5—Co1—O5^i	180.0	C2—N2—C3	108.42 (14)
O5—Co1—N1^i	91.87 (5)	C2—N2—H2	125.8
O5^i—Co1—N1^i	88.13 (5)	C3—N2—H2	125.8
O5—Co1—N1	88.13 (5)	C2—C1—H1A	109.5
O5^i—Co1—N1	91.87 (5)	C2—C1—H1B	109.5
N1^i—Co1—N1	180.0	H1A—C1—H1B	109.5
O5—Co1—O4^i	88.36 (5)	C2—C1—H1C	109.5
O5^i—Co1—O4^i	91.64 (5)	H1A—C1—H1C	109.5
N1^i—Co1—O4^i	77.84 (5)	H1B—C1—H1C	109.5
N1—Co1—O4^i	102.16 (5)	N1—C2—N2	110.00 (15)
O5—Co1—O4	91.64 (5)	N1—C2—C1	125.79 (15)
O5^i—Co1—O4	88.36 (5)	N2—C2—C1	124.21 (16)
N1^i—Co1—O4	102.16 (5)	C4—C3—N2	105.35 (14)
N1—Co1—O4	77.84 (5)	C4—C3—C5	132.11 (17)
O4^i—Co1—O4	180.000 (1)	N2—C3—C5	122.46 (16)
C5—O2—H3	117.1 (11)	C3—C4—N1	109.54 (15)
C6—O3—H3	113.7 (11)	C3—C4—C6	133.06 (15)
C6—O4—Co1	114.58 (10)	N1—C4—C6	117.40 (14)
Co1—O5—H1W	123.2	O1—C5—O2	123.94 (16)
Co1—O5—H2W	123.2	O1—C5—C3	120.47 (16)
H1W—O5—H2W	111.5	O2—C5—C3	115.58 (15)
C2—N1—C4	106.68 (14)	O4—C6—O3	124.21 (15)
C2—N1—Co1	140.96 (12)	O4—C6—C4	117.79 (14)
C4—N1—Co1	112.35 (11)	O3—C6—C4	118.00 (14)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	1.19 (2)	1.28 (2)	2.4619 (18)	168 (2)
O5—H1W···O2^ii	0.82	1.98	2.7920 (18)	171
O5—H2W···O1^iii	0.84	1.95	2.7789 (17)	172
N2—H2···O3^iv	0.86	2.13	2.9564 (18)	162

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