metal-organic compounds
Aquabis(1H-benzimidazole-2-carboxylato-κ2O,N3)zinc(II)
aBasic College Science, Laboratory of Pharmaceutical Chemistry, China Pharmaceutical University, Nanjing, People's Republic of China
*Correspondence e-mail: lut163@163.com
In the title compound, [Zn(C8H5N2O2)2(H2O)], the ZnII ion is coordinated in each case by a carboxylate O atom and an imidazole N atom from two different benzimidazole-2-carboxylate (BIC) ligands and one water O atom in a trigonal-bipyramidal geometry. In the complex molecule, the two benzimidazole planes are twisted, making a dihedral angle of 55.93 (11)°. The three-dimensional framework is organized by intermolecular N—H⋯O hydrogen bonding and O—H⋯O interactions and π–π interactions between adjacent benzimidazole rings [centroid–centroid distance = 3.586 (3) Å].
Related literature
For the biological activity of zinc complexes, see: Yoshikawa et al. (2001); Adachi et al. (2004). For the biological activity of benzimidazole derivatives, see: Shingalapur et al. (2009). For zinc N-heterocyclic or their carboxylate complexes, see: He (2006); Li et al. (2007); Gao et al. (2005). For the structural index τ, see: Addison et al. (1984). For related structures, see: Liu et al. (2004); Lin (2006); Zhong et al. (2006).
Experimental
Crystal data
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Refinement
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Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: CrystalStructure (Rigaku, 2002).
Supporting information
https://doi.org/10.1107/S1600536810015631/kp2256sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810015631/kp2256Isup2.hkl
1H-benzo[d]imidazole-2-carboxylic acid(20 mg, 0.12 mmol) and zinc chloride dihydrate (10 mg, 0.06 mmol) were separately dissolved in 5 ml methanol. The solutions were mixed and stirred magnetically for 2 h. Colourless single crystals were isolated from the solution at room temperature over several days.
At first, all H atoms were located from the difference Fourier maps, and then were treated as riding [C—H = 0.93 Å ; Uiso(H) = 1.2 times Ueq; imidazole N—H = 0.86 Å and O—H = 0.85 Å; Uiso(H) = 1.5 times Ueq]. The weighting schemes were optimized .
Zinc complexes with ligands such as amino acids, picolinic acid, vitamins, and allixin (isolated from garlic) are found to have high in vitro insulinomimetric activity and in vivo anti-diabetic activity (Yoshikawa et al., 2001; Adachi et al., 2004). Although many zinc N-heterocyclic or their carboxylate complexes have been reported(He, 2006; Li et al., 2007; Gao et al., 2005), those related to the benzimidazole-2-carboxylic acid(BICA) are reported rearly. Benzimidazole analogues are known to exhibit a wide variety of pharmacological properties; benzimidazole is an important pharmacophore and privileged structure in medicinal chemistry encompassing a diverse range of biological activities (Shingalapur et al., 2009). In the viewpoint of constructing new functional complex, we prepared aqua(1H-benzo[d]imidazole-2-carboxylato-κ2O:N)-zinc(II) with the formula [Zn(C8H5N2O2)2(H2O)] (I) and report its structure.
In (I) Zn II coordination sphere is completed by carboxylato O atom and imidazole N atom from two different ligand molecules and one O atom from water (Fig. 1). The two BICA molecules are deprotonated to make the molecule neutral, then the BIC- ligand behaves as a chelating unit that binds through the imidazole N atom and carboxylato O atom, giving a five-membered chelate ring. The structural index τ (Addison et al. 1984) which represents the relative amount of trigonality of the five-coordination geometry as τ = 0 for a square pyramid and τ = 1 for a trigonal bipyramida in (I) is 0.791, therefore, the coordination geometry around ZnII seems to be classified as a trigonal bipyramid rather than a square pyramid; N3, O5, and N1 atoms form the equatorial trigonal plane indicated by the angle of O5-Zn-N1 and O5-Zn1-N3 being 116.39 (12) ° and 115.42 (12) °, respectively. The axial position occupy O2 and O4 atoms; O4-Zn-O2 is the only combination with bonding angle close to 180 degrees. Therefore, the five-coordination geometry around Zn is classified as a distorted trigonal bipyramid with ZnN2O3 core. Compared with the other analogous zinc complexes, the bond distance of ZnII and carboxylato O in (I) is in the normal range from 2.1445 (12) Å to 2.201 (3) Å (Table 1), while Zn—O5(water O atom) distance is significantly shorter than in the similar aqua zinc structures, such as 2.1565 (14) Å in [Zn(H2IDC)2(H2O)2] (where H2IDC is the 5-carboxy-1H-imidazole-4-carboxylate ligand (Liu et al., 2004), 2.020 (3) Å in {[Zn(HIDC)(H2O)].0.5H2O}n (HIDC is the imidazole-4,5-dicarboxylate ligand) (Lin, 2006) and 2.1491 (12) Å in [Zn(C5H3N2O4)2(H2O)2].C10H8N2(Zhong et al., 2006).
The benzimidazole moiety in each ligand is nearly coplanar with the mean deviation from plane by 0.0059 Å and 0.0042 Å for ring C1—C7/N1/N2 and C10—C16/N3/N4, respectively. Around ZnII two five-chelate rings are formed with slightly different conformations. The ring Zn1/N1/C7/C8/O2, adopts an π–π interactions between the adjacent benzimidazole planes along the axis a. The pairs of the two benzimidazole rings are oriented almost parallel and overlap face to face with the Cg···Cg distances of 3.586 (3) Å (where Cg is the center of gravity of the benzimidazole ring) for the centroid···centroid separations of rings N1 / N2 / C1— C7 and N1 / N2 / C1— C7(symmetry code: 1-x, y, 3/2-z). The three-dimensional framework is defined by intermolecular hydrogen bonds involving water molecules, the uncoordinated imidazole N atoms, and carboxylate O atoms(N—H···O and O—H···O, Table 2 and Fig. 2).
with the deviation of Zn atom from the mean plane by 0.0686 (16) Å whereas the related ring Zn1/N3/C10/C9/O4 seems to be planar with the corresponding distance 0.0056 (14) Å. The dihedral angle of two benzimidazole groups around ZnII is about 55.93 (11) ° leading to the intersection mode in the stack (Fig.2). In the ab plane, the whole zig-zag motif is bulit up, together with theFor the biological activity of zinc complexes, see: Yoshikawa et al. (2001); Adachi et al. (2004). For the biological activity of benzimidazole derivatives, see: Shingalapur et al. (2009). For zinc N-heterocyclic or their carboxylate complexes, see: He (2006); Li et al. (2007); Gao et al. (2005). For the structural index τ, see: Addison et al. (1984). For related structures, see: Liu et al. (2004); Lin (2006); Zhong et al. (2006).
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell
CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: CrystalStructure (Rigaku, 2002).[Zn(C8H5N2O2)2(H2O)] | F(000) = 1648 |
Mr = 405.67 | Dx = 1.581 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 25 reflections |
a = 25.9702 (15) Å | θ = 10–13° |
b = 10.0870 (6) Å | µ = 1.48 mm−1 |
c = 16.7885 (10) Å | T = 293 K |
β = 129.21 (3)° | Block, colourless |
V = 3407.8 (14) Å3 | 0.20 × 0.10 × 0.10 mm |
Z = 8 |
Enraf–Nonius CAD-4 diffractometer | 2368 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.039 |
Graphite monochromator | θmax = 25.3°, θmin = 2.0° |
ω/2θ scans | h = −31→31 |
Absorption correction: ψ scan (ABSCOR; Higashi, 1995) | k = 0→12 |
Tmin = 0.757, Tmax = 0.866 | l = −20→20 |
6178 measured reflections | 3 standard reflections every 120 min |
3097 independent reflections | intensity decay: 1% |
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)] = 0.039 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.101 | H-atom parameters constrained |
S = 0.99 | w = 1/[σ2(Fo2) + (0.056P)2] where P = (Fo2 + 2Fc2)/3 |
3097 reflections | (Δ/σ)max = 0.001 |
235 parameters | Δρmax = 0.56 e Å−3 |
0 restraints | Δρmin = −0.56 e Å−3 |
[Zn(C8H5N2O2)2(H2O)] | V = 3407.8 (14) Å3 |
Mr = 405.67 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 25.9702 (15) Å | µ = 1.48 mm−1 |
b = 10.0870 (6) Å | T = 293 K |
c = 16.7885 (10) Å | 0.20 × 0.10 × 0.10 mm |
β = 129.21 (3)° |
Enraf–Nonius CAD-4 diffractometer | 2368 reflections with I > 2σ(I) |
Absorption correction: ψ scan (ABSCOR; Higashi, 1995) | Rint = 0.039 |
Tmin = 0.757, Tmax = 0.866 | 3 standard reflections every 120 min |
6178 measured reflections | intensity decay: 1% |
3097 independent reflections |
R[F2 > 2σ(F2)] = 0.039 | 0 restraints |
wR(F2) = 0.101 | H-atom parameters constrained |
S = 0.99 | Δρmax = 0.56 e Å−3 |
3097 reflections | Δρmin = −0.56 e Å−3 |
235 parameters |
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 > 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. |
x | y | z | Uiso*/Ueq | ||
Zn1 | 0.569627 (17) | 0.05468 (4) | 0.69627 (3) | 0.02900 (14) | |
O1 | 0.50351 (16) | 0.3274 (3) | 0.4673 (2) | 0.0650 (9) | |
O2 | 0.54498 (12) | 0.1385 (2) | 0.55532 (17) | 0.0374 (6) | |
O3 | 0.67653 (12) | −0.1506 (2) | 0.97193 (17) | 0.0413 (6) | |
O4 | 0.60004 (11) | −0.0175 (2) | 0.84308 (17) | 0.0364 (6) | |
O5 | 0.48517 (12) | −0.0394 (3) | 0.61712 (19) | 0.0544 (8) | |
H5A | 0.4577 | −0.0325 | 0.5520 | 0.065* | |
H5B | 0.4758 | −0.0872 | 0.6481 | 0.065* | |
N1 | 0.56695 (13) | 0.2485 (3) | 0.7205 (2) | 0.0330 (6) | |
N2 | 0.54861 (16) | 0.4515 (3) | 0.6583 (2) | 0.0433 (8) | |
H2A | 0.5375 | 0.5146 | 0.6156 | 0.052* | |
N3 | 0.64903 (12) | −0.0562 (3) | 0.74399 (19) | 0.0299 (6) | |
N4 | 0.72922 (13) | −0.1867 (3) | 0.8647 (2) | 0.0392 (7) | |
H4A | 0.7536 | −0.2320 | 0.9206 | 0.047* | |
C1 | 0.6165 (2) | 0.4261 (5) | 0.9534 (3) | 0.0632 (12) | |
H1A | 0.6323 | 0.4153 | 1.0204 | 0.076* | |
C2 | 0.6052 (2) | 0.5536 (5) | 0.9134 (3) | 0.0622 (12) | |
H2B | 0.6135 | 0.6254 | 0.9547 | 0.075* | |
C3 | 0.5824 (2) | 0.5773 (4) | 0.8158 (3) | 0.0567 (11) | |
H3A | 0.5750 | 0.6628 | 0.7900 | 0.068* | |
C4 | 0.57069 (19) | 0.4657 (3) | 0.7569 (3) | 0.0422 (9) | |
C5 | 0.58192 (16) | 0.3372 (4) | 0.7962 (3) | 0.0353 (8) | |
C6 | 0.60498 (19) | 0.3157 (4) | 0.8957 (3) | 0.0466 (9) | |
H6A | 0.6123 | 0.2305 | 0.9222 | 0.056* | |
C7 | 0.54749 (17) | 0.3217 (3) | 0.6408 (3) | 0.0351 (8) | |
C8 | 0.52981 (18) | 0.2603 (4) | 0.5450 (3) | 0.0377 (8) | |
C9 | 0.64989 (16) | −0.0943 (3) | 0.8895 (2) | 0.0309 (7) | |
C10 | 0.67732 (15) | −0.1125 (3) | 0.8339 (2) | 0.0295 (7) | |
C11 | 0.68567 (15) | −0.0954 (4) | 0.7139 (2) | 0.0318 (8) | |
C12 | 0.67916 (17) | −0.0663 (4) | 0.6270 (3) | 0.0415 (9) | |
H12A | 0.6452 | −0.0120 | 0.5753 | 0.050* | |
C13 | 0.72500 (19) | −0.1208 (4) | 0.6205 (3) | 0.0514 (11) | |
H13A | 0.7224 | −0.1014 | 0.5640 | 0.062* | |
C14 | 0.7749 (2) | −0.2041 (5) | 0.6966 (3) | 0.0587 (12) | |
H14A | 0.8042 | −0.2410 | 0.6885 | 0.070* | |
C15 | 0.78262 (19) | −0.2338 (4) | 0.7829 (3) | 0.0547 (11) | |
H15A | 0.8167 | −0.2886 | 0.8341 | 0.066* | |
C16 | 0.73686 (17) | −0.1779 (4) | 0.7905 (3) | 0.0378 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn1 | 0.0261 (2) | 0.0311 (2) | 0.0279 (2) | 0.00695 (17) | 0.01612 (17) | 0.00661 (17) |
O1 | 0.110 (3) | 0.0434 (17) | 0.0441 (16) | 0.0153 (17) | 0.0498 (18) | 0.0146 (14) |
O2 | 0.0499 (14) | 0.0327 (14) | 0.0329 (13) | 0.0076 (11) | 0.0277 (12) | 0.0067 (11) |
O3 | 0.0463 (14) | 0.0491 (16) | 0.0300 (13) | 0.0162 (12) | 0.0248 (12) | 0.0143 (12) |
O4 | 0.0365 (13) | 0.0456 (15) | 0.0319 (12) | 0.0156 (11) | 0.0238 (11) | 0.0129 (11) |
O5 | 0.0410 (14) | 0.089 (2) | 0.0384 (15) | −0.0239 (15) | 0.0277 (13) | −0.0217 (14) |
N1 | 0.0356 (15) | 0.0309 (15) | 0.0288 (15) | 0.0036 (12) | 0.0187 (13) | 0.0037 (12) |
N2 | 0.0580 (19) | 0.0310 (17) | 0.0414 (17) | 0.0026 (15) | 0.0316 (16) | 0.0080 (14) |
N3 | 0.0272 (14) | 0.0362 (15) | 0.0250 (14) | 0.0105 (12) | 0.0159 (12) | 0.0095 (12) |
N4 | 0.0362 (16) | 0.0500 (19) | 0.0305 (15) | 0.0204 (14) | 0.0206 (14) | 0.0189 (14) |
C1 | 0.068 (3) | 0.075 (3) | 0.044 (2) | −0.011 (3) | 0.034 (2) | −0.014 (2) |
C2 | 0.074 (3) | 0.054 (3) | 0.056 (3) | −0.014 (2) | 0.041 (3) | −0.025 (2) |
C3 | 0.070 (3) | 0.038 (2) | 0.063 (3) | −0.007 (2) | 0.042 (3) | −0.011 (2) |
C4 | 0.047 (2) | 0.035 (2) | 0.045 (2) | −0.0039 (16) | 0.0293 (19) | −0.0041 (17) |
C5 | 0.0328 (18) | 0.039 (2) | 0.0334 (19) | 0.0000 (16) | 0.0204 (16) | −0.0015 (16) |
C6 | 0.052 (2) | 0.048 (2) | 0.034 (2) | 0.0009 (19) | 0.0247 (19) | 0.0001 (18) |
C7 | 0.041 (2) | 0.0280 (19) | 0.036 (2) | 0.0033 (15) | 0.0245 (17) | 0.0047 (16) |
C8 | 0.045 (2) | 0.037 (2) | 0.0331 (19) | 0.0056 (17) | 0.0257 (17) | 0.0087 (16) |
C9 | 0.0310 (18) | 0.0343 (18) | 0.0245 (17) | 0.0022 (15) | 0.0161 (15) | 0.0026 (15) |
C10 | 0.0247 (16) | 0.0313 (17) | 0.0285 (17) | 0.0064 (14) | 0.0149 (14) | 0.0045 (15) |
C11 | 0.0259 (16) | 0.0411 (19) | 0.0263 (17) | 0.0038 (14) | 0.0156 (15) | 0.0011 (15) |
C12 | 0.0363 (19) | 0.054 (2) | 0.0334 (19) | 0.0130 (18) | 0.0216 (17) | 0.0142 (18) |
C13 | 0.046 (2) | 0.074 (3) | 0.042 (2) | 0.014 (2) | 0.032 (2) | 0.013 (2) |
C14 | 0.046 (2) | 0.086 (3) | 0.059 (3) | 0.026 (2) | 0.040 (2) | 0.017 (2) |
C15 | 0.042 (2) | 0.076 (3) | 0.049 (2) | 0.031 (2) | 0.031 (2) | 0.024 (2) |
C16 | 0.0327 (18) | 0.047 (2) | 0.0341 (19) | 0.0130 (16) | 0.0212 (16) | 0.0104 (17) |
Zn1—O5 | 1.947 (3) | C1—C2 | 1.393 (6) |
Zn1—N1 | 2.007 (3) | C1—H1A | 0.9300 |
Zn1—N3 | 2.014 (2) | C2—C3 | 1.365 (6) |
Zn1—O4 | 2.184 (2) | C2—H2B | 0.9300 |
Zn1—O2 | 2.193 (2) | C3—C4 | 1.400 (5) |
O1—C8 | 1.224 (4) | C3—H3A | 0.9300 |
O2—C8 | 1.268 (4) | C4—C5 | 1.398 (5) |
O3—C9 | 1.227 (4) | C5—C6 | 1.390 (5) |
O4—C9 | 1.268 (4) | C6—H6A | 0.9300 |
O5—H5A | 0.8500 | C7—C8 | 1.500 (5) |
O5—H5B | 0.8500 | C9—C10 | 1.502 (4) |
N1—C7 | 1.318 (4) | C11—C12 | 1.389 (5) |
N1—C5 | 1.394 (4) | C11—C16 | 1.397 (5) |
N2—C7 | 1.338 (4) | C12—C13 | 1.377 (5) |
N2—C4 | 1.375 (5) | C12—H12A | 0.9300 |
N2—H2A | 0.8600 | C13—C14 | 1.387 (5) |
N3—C10 | 1.318 (4) | C13—H13A | 0.9300 |
N3—C11 | 1.387 (4) | C14—C15 | 1.366 (5) |
N4—C10 | 1.328 (4) | C14—H14A | 0.9300 |
N4—C16 | 1.383 (4) | C15—C16 | 1.391 (5) |
N4—H4A | 0.8600 | C15—H15A | 0.9300 |
C1—C6 | 1.379 (6) | ||
O5—Zn1—N1 | 116.39 (12) | C3—C4—C5 | 121.7 (4) |
O5—Zn1—N3 | 115.42 (12) | N1—C5—C6 | 131.0 (3) |
N1—Zn1—N3 | 128.19 (11) | N1—C5—C4 | 108.1 (3) |
O5—Zn1—O4 | 93.18 (11) | C6—C5—C4 | 120.9 (3) |
N1—Zn1—O4 | 97.49 (10) | C1—C6—C5 | 117.1 (4) |
N3—Zn1—O4 | 79.46 (9) | C1—C6—H6A | 121.5 |
O5—Zn1—O2 | 90.98 (11) | C5—C6—H6A | 121.5 |
N1—Zn1—O2 | 79.56 (10) | N1—C7—N2 | 112.6 (3) |
N3—Zn1—O2 | 99.82 (10) | N1—C7—C8 | 121.2 (3) |
O4—Zn1—O2 | 175.67 (9) | N2—C7—C8 | 126.1 (3) |
C8—O2—Zn1 | 112.0 (2) | O1—C8—O2 | 126.7 (3) |
C9—O4—Zn1 | 113.4 (2) | O1—C8—C7 | 120.0 (3) |
Zn1—O5—H5A | 120.4 | O2—C8—C7 | 113.3 (3) |
Zn1—O5—H5B | 119.6 | O3—C9—O4 | 127.2 (3) |
H5A—O5—H5B | 120.0 | O3—C9—C10 | 119.6 (3) |
C7—N1—C5 | 105.8 (3) | O4—C9—C10 | 113.2 (3) |
C7—N1—Zn1 | 112.4 (2) | N3—C10—N4 | 112.5 (3) |
C5—N1—Zn1 | 141.7 (2) | N3—C10—C9 | 121.3 (3) |
C7—N2—C4 | 107.5 (3) | N4—C10—C9 | 126.2 (3) |
C7—N2—H2A | 126.3 | C12—C11—N3 | 131.7 (3) |
C4—N2—H2A | 126.3 | C12—C11—C16 | 120.3 (3) |
C10—N3—C11 | 106.3 (3) | N3—C11—C16 | 107.9 (3) |
C10—N3—Zn1 | 112.6 (2) | C13—C12—C11 | 117.5 (3) |
C11—N3—Zn1 | 141.2 (2) | C13—C12—H12A | 121.3 |
C10—N4—C16 | 107.5 (3) | C11—C12—H12A | 121.3 |
C10—N4—H4A | 126.2 | C12—C13—C14 | 121.4 (4) |
C16—N4—H4A | 126.2 | C12—C13—H13A | 119.3 |
C6—C1—C2 | 121.4 (4) | C14—C13—H13A | 119.3 |
C6—C1—H1A | 119.3 | C15—C14—C13 | 122.3 (4) |
C2—C1—H1A | 119.3 | C15—C14—H14A | 118.9 |
C3—C2—C1 | 122.6 (4) | C13—C14—H14A | 118.9 |
C3—C2—H2B | 118.7 | C14—C15—C16 | 116.6 (3) |
C1—C2—H2B | 118.7 | C14—C15—H15A | 121.7 |
C2—C3—C4 | 116.3 (4) | C16—C15—H15A | 121.7 |
C2—C3—H3A | 121.9 | N4—C16—C15 | 132.3 (3) |
C4—C3—H3A | 121.9 | N4—C16—C11 | 105.8 (3) |
N2—C4—C3 | 132.3 (4) | C15—C16—C11 | 121.9 (3) |
N2—C4—C5 | 106.0 (3) | ||
O5—Zn1—O2—C8 | 105.9 (2) | Zn1—N1—C7—N2 | −177.1 (2) |
N1—Zn1—O2—C8 | −10.8 (2) | C5—N1—C7—C8 | 177.4 (3) |
N3—Zn1—O2—C8 | −138.1 (2) | Zn1—N1—C7—C8 | 0.2 (4) |
O5—Zn1—O4—C9 | 113.9 (2) | C4—N2—C7—N1 | 0.3 (4) |
N1—Zn1—O4—C9 | −128.9 (2) | C4—N2—C7—C8 | −176.9 (3) |
N3—Zn1—O4—C9 | −1.3 (2) | Zn1—O2—C8—O1 | −166.9 (3) |
O5—Zn1—N1—C7 | −80.8 (3) | Zn1—O2—C8—C7 | 13.2 (4) |
N3—Zn1—N1—C7 | 99.4 (2) | N1—C7—C8—O1 | 170.2 (3) |
O4—Zn1—N1—C7 | −178.1 (2) | N2—C7—C8—O1 | −12.9 (6) |
O2—Zn1—N1—C7 | 5.1 (2) | N1—C7—C8—O2 | −9.9 (5) |
O5—Zn1—N1—C5 | 103.6 (4) | N2—C7—C8—O2 | 167.0 (3) |
N3—Zn1—N1—C5 | −76.2 (4) | Zn1—O4—C9—O3 | −178.6 (3) |
O4—Zn1—N1—C5 | 6.3 (4) | Zn1—O4—C9—C10 | 2.2 (4) |
O2—Zn1—N1—C5 | −170.5 (4) | C11—N3—C10—N4 | −0.7 (4) |
O5—Zn1—N3—C10 | −88.5 (2) | Zn1—N3—C10—N4 | 179.3 (2) |
N1—Zn1—N3—C10 | 91.3 (3) | C11—N3—C10—C9 | −178.7 (3) |
O4—Zn1—N3—C10 | 0.0 (2) | Zn1—N3—C10—C9 | 1.3 (4) |
O2—Zn1—N3—C10 | 175.6 (2) | C16—N4—C10—N3 | 0.9 (4) |
O5—Zn1—N3—C11 | 91.5 (4) | C16—N4—C10—C9 | 178.9 (3) |
N1—Zn1—N3—C11 | −88.7 (4) | O3—C9—C10—N3 | 178.3 (3) |
O4—Zn1—N3—C11 | 180.0 (4) | O4—C9—C10—N3 | −2.5 (5) |
O2—Zn1—N3—C11 | −4.4 (4) | O3—C9—C10—N4 | 0.5 (5) |
C6—C1—C2—C3 | −0.2 (7) | O4—C9—C10—N4 | 179.8 (3) |
C1—C2—C3—C4 | 0.1 (7) | C10—N3—C11—C12 | −179.6 (4) |
C7—N2—C4—C3 | 179.0 (4) | Zn1—N3—C11—C12 | 0.4 (7) |
C7—N2—C4—C5 | −0.5 (4) | C10—N3—C11—C16 | 0.1 (4) |
C2—C3—C4—N2 | −179.5 (4) | Zn1—N3—C11—C16 | −179.8 (3) |
C2—C3—C4—C5 | −0.1 (6) | N3—C11—C12—C13 | 179.3 (4) |
C7—N1—C5—C6 | −179.6 (4) | C16—C11—C12—C13 | −0.4 (5) |
Zn1—N1—C5—C6 | −3.8 (6) | C11—C12—C13—C14 | 1.4 (6) |
C7—N1—C5—C4 | −0.4 (4) | C12—C13—C14—C15 | −1.8 (7) |
Zn1—N1—C5—C4 | 175.3 (3) | C13—C14—C15—C16 | 1.1 (7) |
N2—C4—C5—N1 | 0.6 (4) | C10—N4—C16—C15 | 179.6 (4) |
C3—C4—C5—N1 | −179.0 (3) | C10—N4—C16—C11 | −0.8 (4) |
N2—C4—C5—C6 | 179.9 (3) | C14—C15—C16—N4 | 179.4 (4) |
C3—C4—C5—C6 | 0.3 (6) | C14—C15—C16—C11 | −0.1 (6) |
C2—C1—C6—C5 | 0.4 (6) | C12—C11—C16—N4 | −179.9 (3) |
N1—C5—C6—C1 | 178.6 (4) | N3—C11—C16—N4 | 0.4 (4) |
C4—C5—C6—C1 | −0.5 (6) | C12—C11—C16—C15 | −0.2 (6) |
C5—N1—C7—N2 | 0.1 (4) | N3—C11—C16—C15 | −180.0 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O1i | 0.86 | 1.93 | 2.765 (4) | 162 |
N4—H4A···O3ii | 0.86 | 1.95 | 2.778 (4) | 161 |
O5—H5A···O2iii | 0.85 | 2.06 | 2.670 (4) | 128 |
O5—H5B···O4iv | 0.85 | 2.18 | 2.695 (5) | 119 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+3/2, −y−1/2, −z+2; (iii) −x+1, −y, −z+1; (iv) −x+1, y, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | [Zn(C8H5N2O2)2(H2O)] |
Mr | 405.67 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 25.9702 (15), 10.0870 (6), 16.7885 (10) |
β (°) | 129.21 (3) |
V (Å3) | 3407.8 (14) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.48 |
Crystal size (mm) | 0.20 × 0.10 × 0.10 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 |
Absorption correction | ψ scan (ABSCOR; Higashi, 1995) |
Tmin, Tmax | 0.757, 0.866 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6178, 3097, 2368 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.601 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.039, 0.101, 0.99 |
No. of reflections | 3097 |
No. of parameters | 235 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.56, −0.56 |
Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), CrystalStructure (Rigaku, 2002).
Zn1—O5 | 1.947 (3) | Zn1—O4 | 2.184 (2) |
Zn1—N1 | 2.007 (3) | Zn1—O2 | 2.193 (2) |
Zn1—N3 | 2.014 (2) | ||
O5—Zn1—N1 | 116.39 (12) | N3—Zn1—O4 | 79.46 (9) |
O5—Zn1—N3 | 115.42 (12) | O5—Zn1—O2 | 90.98 (11) |
N1—Zn1—N3 | 128.19 (11) | N1—Zn1—O2 | 79.56 (10) |
O5—Zn1—O4 | 93.18 (11) | N3—Zn1—O2 | 99.82 (10) |
N1—Zn1—O4 | 97.49 (10) | O4—Zn1—O2 | 175.67 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O1i | 0.86 | 1.93 | 2.765 (4) | 162 |
N4—H4A···O3ii | 0.86 | 1.95 | 2.778 (4) | 161 |
O5—H5A···O2iii | 0.85 | 2.06 | 2.670 (4) | 128 |
O5—H5B···O4iv | 0.85 | 2.18 | 2.695 (5) | 119 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+3/2, −y−1/2, −z+2; (iii) −x+1, −y, −z+1; (iv) −x+1, y, −z+3/2. |
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Zinc complexes with ligands such as amino acids, picolinic acid, vitamins, and allixin (isolated from garlic) are found to have high in vitro insulinomimetric activity and in vivo anti-diabetic activity (Yoshikawa et al., 2001; Adachi et al., 2004). Although many zinc N-heterocyclic or their carboxylate complexes have been reported(He, 2006; Li et al., 2007; Gao et al., 2005), those related to the benzimidazole-2-carboxylic acid(BICA) are reported rearly. Benzimidazole analogues are known to exhibit a wide variety of pharmacological properties; benzimidazole is an important pharmacophore and privileged structure in medicinal chemistry encompassing a diverse range of biological activities (Shingalapur et al., 2009). In the viewpoint of constructing new functional complex, we prepared aqua(1H-benzo[d]imidazole-2-carboxylato-κ2O:N)-zinc(II) with the formula [Zn(C8H5N2O2)2(H2O)] (I) and report its structure.
In (I) Zn II coordination sphere is completed by carboxylato O atom and imidazole N atom from two different ligand molecules and one O atom from water (Fig. 1). The two BICA molecules are deprotonated to make the molecule neutral, then the BIC- ligand behaves as a chelating unit that binds through the imidazole N atom and carboxylato O atom, giving a five-membered chelate ring. The structural index τ (Addison et al. 1984) which represents the relative amount of trigonality of the five-coordination geometry as τ = 0 for a square pyramid and τ = 1 for a trigonal bipyramida in (I) is 0.791, therefore, the coordination geometry around ZnII seems to be classified as a trigonal bipyramid rather than a square pyramid; N3, O5, and N1 atoms form the equatorial trigonal plane indicated by the angle of O5-Zn-N1 and O5-Zn1-N3 being 116.39 (12) ° and 115.42 (12) °, respectively. The axial position occupy O2 and O4 atoms; O4-Zn-O2 is the only combination with bonding angle close to 180 degrees. Therefore, the five-coordination geometry around Zn is classified as a distorted trigonal bipyramid with ZnN2O3 core. Compared with the other analogous zinc complexes, the bond distance of ZnII and carboxylato O in (I) is in the normal range from 2.1445 (12) Å to 2.201 (3) Å (Table 1), while Zn—O5(water O atom) distance is significantly shorter than in the similar aqua zinc structures, such as 2.1565 (14) Å in [Zn(H2IDC)2(H2O)2] (where H2IDC is the 5-carboxy-1H-imidazole-4-carboxylate ligand (Liu et al., 2004), 2.020 (3) Å in {[Zn(HIDC)(H2O)].0.5H2O}n (HIDC is the imidazole-4,5-dicarboxylate ligand) (Lin, 2006) and 2.1491 (12) Å in [Zn(C5H3N2O4)2(H2O)2].C10H8N2(Zhong et al., 2006).
The benzimidazole moiety in each ligand is nearly coplanar with the mean deviation from plane by 0.0059 Å and 0.0042 Å for ring C1—C7/N1/N2 and C10—C16/N3/N4, respectively. Around ZnII two five-chelate rings are formed with slightly different conformations. The ring Zn1/N1/C7/C8/O2, adopts an envelope conformation with the deviation of Zn atom from the mean plane by 0.0686 (16) Å whereas the related ring Zn1/N3/C10/C9/O4 seems to be planar with the corresponding distance 0.0056 (14) Å. The dihedral angle of two benzimidazole groups around ZnII is about 55.93 (11) ° leading to the intersection mode in the stack (Fig.2). In the ab plane, the whole zig-zag motif is bulit up, together with the π–π interactions between the adjacent benzimidazole planes along the axis a. The pairs of the two benzimidazole rings are oriented almost parallel and overlap face to face with the Cg···Cg distances of 3.586 (3) Å (where Cg is the center of gravity of the benzimidazole ring) for the centroid···centroid separations of rings N1 / N2 / C1— C7 and N1 / N2 / C1— C7(symmetry code: 1-x, y, 3/2-z). The three-dimensional framework is defined by intermolecular hydrogen bonds involving water molecules, the uncoordinated imidazole N atoms, and carboxylate O atoms(N—H···O and O—H···O, Table 2 and Fig. 2).