Diaqua­bis­(1H-imidazole-4-carboxyl­ato-κ² N ³,O)cobalt(II)

Abstract

In the title compound, [Co(C₄H₃N₂O₂)₂(H₂O)₂], the Co^II ion is located on a twofold rotation axis and shows a distorted octa­hedral coordination configuration, defined by two N,O-bidentate 1H-imidazole-4-carboxyl­ate ligands in the equatorial plane and two water mol­ecules in the axial positions. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional supra­molecular network. π–π stacking inter­actions between the imidazole rings [centroid–centroid distances = 3.4914 (15) and 3.6167 (15) Å] further stabilize the crystal structure.

Related literature  

For related structures, see: Cai et al. (2012 ▶); Gryz et al. (2007 ▶); Haggag (2005 ▶); Shuai et al. (2011 ▶); Starosta & Leciejewicz (2006 ▶); Yin et al. (2009 ▶); Zheng et al. (2011 ▶).

Experimental  

Crystal data  

• [Co(C₄H₃N₂O₂)₂(H₂O)₂]

• M _r = 317.13

• Orthorhombic,

• a = 7.1216 (18) Å

• b = 11.780 (3) Å

• c = 13.536 (3) Å

• V = 1135.6 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 1.54 mm⁻¹

• T = 298 K

• 0.35 × 0.33 × 0.30 mm

Data collection  

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.614, T _max = 0.655

• 6171 measured reflections

• 1238 independent reflections

• 1050 reflections with I > 2σ(I)

• R _int = 0.024

Refinement  

• R[F ² > 2σ(F ²)] = 0.027

• wR(F ²) = 0.073

• S = 1.08

• 1238 reflections

• 87 parameters

• H-atom parameters constrained

• Δρ_max = 0.29 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶) and PLATON (Spek, 2009 ▶); 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
O1W—H1WA⋯O2i	0.87	1.99	2.827 (2)	162
O1W—H1WB⋯O2ii	0.86	1.93	2.771 (2)	166
N2—H2⋯O2iii	0.86	1.92	2.771 (2)	173

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

There is currently much interest in adopting heterocyclic carboxylic acids as multidentate ligands to prepare new metal coordination polymers. The main reason is that they have versatile coordination behaviors and can form high-dimensional polymers via hydrogen-bonding interactions in the process of self-assembly. 1H-Imidazole-4-carboxylic acid (H₂imc), containing two N atoms of an imidazole group and one carboxylate group, is an excellent candidate for the construction of new coordination polymers. Up to this date, one-, two- and three-dimensional coordination polymers based on the H₂imc ligand have been documented (Cai et al., 2012; Haggag, 2005; Gryz et al., 2007; Shuai et al., 2011; Starosta & Leciejewicz, 2006; Yin et al., 2009; Zheng et al., 2011). For example, the mononuclear complexes [Cd(Himc)₂(H₂O)₂] and [Zn(Himc)₂(H₂O)₂] have been reported by Yin et al. (2009) and Shuai et al. (2011), repectively. In this work, we report a Co(II) coordination polymer, [Co(Himc)₂(H₂O)₂], which is isomorphous with the Cd(II) and Zn(II) analogs.

The asymmetric unit of the title compound contains a half of Co^II ion, lying on a twofold rotation axis, one Himc anion and one coordinated water molecule. As illustrated in Fig. 1, the Co^II ion is six-coordinated by two N and two O atoms from two cis-oriented N,O-bidentate Himc ligands in the equatorial plane, and two water molecules in the axial positions, forming a slightly distorted octahedral geometry. The Co—N bond length is 2.0786 (16) Å and the Co—O distances are 2.1088 (15) and 2.1793 (14) Å, which are comparable to those of the Cd^II and Zn^II analogs. In the crystal structure, a pairs of intermolecular O—H···O hydrogen bonds (Table 1) involving the coordinated water (O1W) and the carboxylate O atom (O2) link the molecules into a two-dimensional network in the ab plane (Fig. 2). In addition, there exist strong π–π stacking interactions between the imidazole rings in the layer, with a centroid–centroid distatance of 3.4914 (15) Å. These layers are further connected by N—H···O hydrogen bonds (Table 1) involving the imidazole N atom (N2) and the carboxylate O atom (O2), generating a three-dimensional supramolecular network. Another type of π–π stacking interactions with a centroid–centroid distatance of 3.6167 (15) Å also can be observed between the neighbouring layers (Fig. 3).

Experimental

A mixture of CoCl₂.6H₂O (0.20 mmol), H₂imc (0.20 mmol) and 6 ml EtOH/H₂O (v/v 1:1) was sealed into a 10 ml sample bottle reactor and heated at 373 K for 48 h under autogenous pressure, and then slowly cooled to room temperature at a rate of 2 K/h. Red block crystals of the title compound were isolated, washed with distilled water, and dried in air (yield: 45%).

Refinement

C- and N-bound H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 and N—H = 0.86 Å and with U_iso(H) = 1.2U_eq(C, N). H atoms of the water molecule were located from a difference Fourier map and refined as riding, with O—H bond lenghts restrained to 0.86 Å.

Figures

Fig. 1.

The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. [Symmetry code: (i) -x+3/2, -y+1/2, z.]

Fig. 2.

The crystal packing of the title compound, showing the two-dimensional network. Hydrogen bonds and π–π staking interactions are shown as dashed lines.

Fig. 3.

The crystal packing of the title compound, showing the three-dimensional supramolecular network. Hydrogen bonds and π–π staking interactions are shown as dashed lines.

Crystal data

[Co(C4H3N2O2)2(H2O)2]	F(000) = 644
Mr = 317.13	Dx = 1.855 Mg m−3
Orthorhombic, Pccn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2ac	Cell parameters from 2075 reflections
a = 7.1216 (18) Å	θ = 3.0–27.3°
b = 11.780 (3) Å	µ = 1.54 mm−1
c = 13.536 (3) Å	T = 298 K
V = 1135.6 (5) Å3	Block, red
Z = 4	0.35 × 0.33 × 0.30 mm

Data collection

Bruker APEXII CCD diffractometer	1238 independent reflections
Radiation source: fine-focus sealed tube	1050 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
φ and ω scans	θmax = 27.0°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −9→9
Tmin = 0.614, Tmax = 0.655	k = −12→15
6171 measured reflections	l = −17→16

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.073	H-atom parameters constrained
S = 1.08	w = 1/[σ2(Fo2) + (0.0317P)2 + 0.7299P] where P = (Fo2 + 2Fc2)/3
1238 reflections	(Δ/σ)max < 0.001
87 parameters	Δρmax = 0.29 e Å−3
0 restraints	Δρmin = −0.25 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
Co1	0.7500	0.2500	0.13193 (2)	0.02397 (14)
O1	0.95746 (19)	0.17187 (13)	0.22880 (10)	0.0305 (3)
O1W	0.8973 (2)	0.40251 (13)	0.15738 (11)	0.0351 (4)
O2	1.23719 (18)	0.08486 (12)	0.22678 (10)	0.0302 (3)
N1	0.9449 (2)	0.18857 (14)	0.03090 (11)	0.0270 (4)
C3	1.2150 (3)	0.09661 (18)	0.00537 (15)	0.0304 (4)
H3	1.3262	0.0569	0.0155	0.036*
C1	1.0961 (3)	0.12982 (16)	0.18488 (14)	0.0243 (4)
C2	1.0934 (3)	0.13421 (16)	0.07551 (14)	0.0235 (4)
C4	0.9791 (3)	0.18410 (18)	−0.06466 (14)	0.0314 (5)
H4	0.9018	0.2150	−0.1131	0.038*
N2	1.1403 (2)	0.12911 (15)	−0.08276 (12)	0.0327 (4)
H2	1.1882	0.1166	−0.1401	0.039*
H1WA	0.8364	0.4481	0.1962	0.039*
H1WB	1.0072	0.3950	0.1833	0.039*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Co1	0.0206 (2)	0.0304 (2)	0.0209 (2)	0.00483 (15)	0.000	0.000
O1	0.0258 (8)	0.0427 (8)	0.0230 (7)	0.0060 (6)	0.0011 (6)	−0.0005 (6)
O1W	0.0241 (8)	0.0367 (8)	0.0445 (9)	0.0039 (6)	−0.0032 (6)	−0.0095 (7)
O2	0.0225 (7)	0.0413 (8)	0.0267 (7)	0.0027 (6)	−0.0034 (6)	0.0047 (6)
N1	0.0252 (9)	0.0331 (9)	0.0226 (8)	0.0046 (7)	0.0017 (6)	0.0016 (7)
C3	0.0258 (10)	0.0356 (11)	0.0297 (10)	0.0038 (8)	0.0005 (8)	−0.0026 (9)
C1	0.0233 (10)	0.0246 (9)	0.0251 (9)	−0.0032 (7)	−0.0019 (8)	0.0010 (8)
C2	0.0218 (10)	0.0251 (9)	0.0237 (9)	0.0005 (7)	−0.0002 (7)	0.0007 (7)
C4	0.0303 (11)	0.0408 (12)	0.0230 (10)	0.0041 (9)	0.0004 (8)	0.0031 (9)
N2	0.0327 (10)	0.0424 (10)	0.0231 (8)	0.0023 (8)	0.0073 (7)	−0.0015 (7)

Geometric parameters (Å, º)

Co1—N1	2.0786 (16)	N1—C2	1.376 (2)
Co1—O1W	2.1088 (15)	C3—C2	1.359 (3)
Co1—O1	2.1793 (14)	C3—N2	1.361 (3)
O1—C1	1.254 (2)	C3—H3	0.9300
O1W—H1WA	0.87	C1—C2	1.482 (3)
O1W—H1WB	0.86	C4—N2	1.341 (3)
O2—C1	1.269 (2)	C4—H4	0.9300
N1—C4	1.317 (2)	N2—H2	0.8600
N1i—Co1—N1	97.72 (9)	C4—N1—C2	105.69 (16)
N1i—Co1—O1W	98.23 (6)	C4—N1—Co1	141.57 (14)
N1—Co1—O1W	94.12 (6)	C2—N1—Co1	112.73 (12)
N1i—Co1—O1Wi	94.12 (6)	C2—C3—N2	105.76 (18)
N1—Co1—O1Wi	98.23 (6)	C2—C3—H3	127.1
O1W—Co1—O1Wi	161.19 (9)	N2—C3—H3	127.1
N1i—Co1—O1	174.63 (6)	O1—C1—O2	125.17 (18)
N1—Co1—O1	78.23 (6)	O1—C1—C2	116.70 (16)
O1W—Co1—O1	85.65 (6)	O2—C1—C2	118.13 (17)
O1Wi—Co1—O1	83.06 (6)	C3—C2—N1	109.55 (17)
N1i—Co1—O1i	78.23 (6)	C3—C2—C1	132.70 (18)
N1—Co1—O1i	174.63 (6)	N1—C2—C1	117.72 (16)
O1W—Co1—O1i	83.06 (6)	N1—C4—N2	110.91 (18)
O1Wi—Co1—O1i	85.65 (6)	N1—C4—H4	124.5
O1—Co1—O1i	106.02 (7)	N2—C4—H4	124.5
C1—O1—Co1	114.54 (12)	C4—N2—C3	108.07 (17)
Co1—O1W—H1WA	112.2	C4—N2—H2	126.0
Co1—O1W—H1WB	115.5	C3—N2—H2	126.0
H1WA—O1W—H1WB	105.7
N1—Co1—O1—C1	1.74 (14)	N2—C3—C2—N1	0.4 (2)
O1W—Co1—O1—C1	−93.39 (14)	N2—C3—C2—C1	−177.63 (19)
O1Wi—Co1—O1—C1	101.68 (14)	C4—N1—C2—C3	−0.5 (2)
O1i—Co1—O1—C1	−174.89 (15)	Co1—N1—C2—C3	−179.88 (13)
N1i—Co1—N1—C4	4.6 (2)	C4—N1—C2—C1	177.83 (17)
O1W—Co1—N1—C4	−94.3 (2)	Co1—N1—C2—C1	−1.5 (2)
O1Wi—Co1—N1—C4	99.9 (2)	O1—C1—C2—C3	−179.0 (2)
O1—Co1—N1—C4	−179.0 (2)	O2—C1—C2—C3	1.4 (3)
N1i—Co1—N1—C2	−176.42 (16)	O1—C1—C2—N1	3.1 (2)
O1W—Co1—N1—C2	84.68 (14)	O2—C1—C2—N1	−176.53 (17)
O1Wi—Co1—N1—C2	−81.10 (14)	C2—N1—C4—N2	0.5 (2)
O1—Co1—N1—C2	0.00 (13)	Co1—N1—C4—N2	179.49 (16)
Co1—O1—C1—O2	176.63 (15)	N1—C4—N2—C3	−0.2 (2)
Co1—O1—C1—C2	−3.0 (2)	C2—C3—N2—C4	−0.1 (2)

Symmetry code: (i) −x+3/2, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O2ii	0.87	1.99	2.827 (2)	162
O1W—H1WB···O2iii	0.86	1.93	2.771 (2)	166
N2—H2···O2iv	0.86	1.92	2.771 (2)	173

Symmetry codes: (ii) −x+2, y+1/2, −z+1/2; (iii) −x+5/2, −y+1/2, z; (iv) −x+5/2, y, z−1/2.