metal-organic compounds
Guanidinium hexaaquazinc(II) bis[tris(3-carboxypyridine-2-carboxylato)zincate]
aDepartment of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran, bDepartment of Chemistry, Faculty of Science, Khorramabad Branch, Islamic Azad University, Khorramabad, Iran, and cYoung researchers Club, Science and Research Branch, Islamic Azad University, Tehran, Iran
*Correspondence e-mail: tabatabaee45m@yahoo.com
In the title molecular salt, (CH6N3)1.30[Zn(H2O)6]0.35[Zn(C7H4NO4)3]2, the ZnII atom (site symmetry 3) in the anion is coordinated by three N,O-bidentate 3-carboxypyridine-2-carboxylate monoanions to generate a fac-ZnN3O3 octahedral coordination geometry. The guanidinium cation (the C atom has 3) and the octahedral hexaaquazinc(II) dication (the Zn2+ cation has -3) are occupationally disordered in a 1.30:0.35 ratio. In the crystal, the components are linked by O—H⋯O and N—H⋯O hydrogen bonds to generate infinite (001) sheets. Weak aromatic π–π stacking [centroid–centroid distance = 3.797 (8) Å] is also observed in the crystal.
Related literature
For related structures, see: Tabatabaee, Abbasi et al. (2011); Tabatabaee, Razavimahmoudabadi et al. (2011).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 1998); cell SAINT-Plus (Bruker, 1998); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S160053681202987X/hb6768sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681202987X/hb6768Isup2.hkl
An aqueous solution of pyridine-2,3-dicarboxylic acid (0.10 g, 0.67 mmol)) and Zn(NO3)2.6H2O (0.09 g, 0.3 mmol) was added to an aqueous solution of guanidine hydrochloride (0.08 g, 0.84 mmol) and NaOH (0.04 g, 1 mmol). The reaction mixture was stirred at 25°C for 3 h. Colorless prisms of the title compound were obtained after few days.
The hydrogen atoms of NH groups (water molecules) were found in difference Fourier synthesis. The H(C) atom positions were calculated. All hydrogen atoms were refined in isotropic approximation in riding model with the Uiso(H) parameters equal to 1.2 Ueq(Ci), for methyl groups equal to 1.5 Ueq(Cii), where U(Ci) and U(Cii) are respectively the equivalent thermal parameters of the carbon atoms to which corresponding H atoms are bonded.
Unlike pyridine-2,6-dicarboxylic acid, which is an O,N,O-tridentate ligand (e.g. Tabatabaee, Abbasi et al., 2011), pyridine-2,3-dicarboxylic acid often acts as a bidentate chelating ligand through nitrogen and one oxygen atom of the 2-position carboxylic group, while the 3-position carboxylate oxygen atom can act as a bridging atom between metal ions to form a coordination polymer. Recently, we have reported the synthesis and characterization of two one-dimensional coordination polymers of Cd2+ and Co2+ with pyridine-2,3-dicarboxylic acid (2,3-H2pydc) (Tabatabaee, Razavimahmoudabadi et al., 2011) and in this study we wish to report the
of a mononuclear Zn(II) complex with (2,3-H2pydc) in the presence of guanidine hydrochloride.The title compound consists of [Zn(2,3-Hpydc)3]- anions, (GH)+ and [Zn(H2O)6]2+ cations (Fig. 1). Two variant of [Zn(2,3-pydcH)3]- anions exist in 1 and to balance the charges, one protonated guanidinium cation and [Zn(H2O)6]2+ are present in 1.30: 0.35 ratio. Zn(II) ion in the title compound is six-coordinated by three (2,3-pydcH)2– anions in O,N-bidentate fashion and the geometry of the resulting ZnN3O3 coordination can be described as distorted octahedral. The bond angles around Zn(II) ion involving trans pairs of donor atoms are 165.33 (7) and for the cis pairs of donor atoms are in the range of 77.27 (7)– 98.26 (8)°. The bond distances Zn–N and Zn–O in are in accordance with those in related structures (Tabatabaee, Razavimahmoudabadi et al., 2011).
There is some hydrogen bonding interactions such as O—H···O, N—H···O between cations and anions. As was shown in figure 2, Hydrogen bonding interactions contribute to the formation of a two dimensional network cavity structure. There is also π-π stacking interactions between the aromatic rings defined by atoms N1/C2 /C6/C5/C4/C3 [symmetry code: 1-X,1-Y,1-Z; centroid-centroid distance 3.797 (8) Å; the angle between the planes 0°; the perpendicular distance between the planes 3.588 Å; the slippage 1.24 Å]. Ion pairing, hydrogen bonding, π–π stacking and van der Waals interactions are also effective for packing of the (Fig 3).
For related structures, see: Tabatabaee, Abbasi et al. (2011); Tabatabaee, Razavimahmoudabadi et al. (2011).
Data collection: SMART (Bruker, 1998); cell
SAINT-Plus (Bruker, 1998); data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).(CH6N3)1.30[Zn(H2O)6]0.35[Zn(C7H4NO4)3]2 | Dx = 1.799 Mg m−3 |
Mr = 1266.24 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, P3 | Cell parameters from 524 reflections |
Hall symbol: -P 3 | θ = 3–30° |
a = 14.5775 (16) Å | µ = 1.31 mm−1 |
c = 6.3506 (16) Å | T = 120 K |
V = 1168.7 (3) Å3 | Prism, colorless |
Z = 1 | 0.25 × 0.25 × 0.20 mm |
F(000) = 644 |
Bruker SMART 1000 CCD diffractometer | 2079 independent reflections |
Radiation source: fine-focus sealed tube | 1443 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.044 |
φ and ω scans | θmax = 29.0°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Bruker, 1998) | h = −11→13 |
Tmin = 0.731, Tmax = 0.773 | k = −15→19 |
4304 measured reflections | l = −5→8 |
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)] = 0.045 | Hydrogen site location: mixed |
wR(F2) = 0.106 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0393P)2 + 0.497P] where P = (Fo2 + 2Fc2)/3 |
2079 reflections | (Δ/σ)max < 0.001 |
129 parameters | Δρmax = 0.88 e Å−3 |
0 restraints | Δρmin = −0.69 e Å−3 |
(CH6N3)1.30[Zn(H2O)6]0.35[Zn(C7H4NO4)3]2 | Z = 1 |
Mr = 1266.24 | Mo Kα radiation |
Trigonal, P3 | µ = 1.31 mm−1 |
a = 14.5775 (16) Å | T = 120 K |
c = 6.3506 (16) Å | 0.25 × 0.25 × 0.20 mm |
V = 1168.7 (3) Å3 |
Bruker SMART 1000 CCD diffractometer | 2079 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1998) | 1443 reflections with I > 2σ(I) |
Tmin = 0.731, Tmax = 0.773 | Rint = 0.044 |
4304 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.106 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.00 | Δρmax = 0.88 e Å−3 |
2079 reflections | Δρmin = −0.69 e Å−3 |
129 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Zn1 | 0.6667 | 0.3333 | 0.70631 (8) | 0.02632 (17) | |
N1 | 0.65271 (16) | 0.45142 (17) | 0.5247 (3) | 0.0244 (5) | |
O2 | 0.80453 (15) | 0.64188 (14) | 0.9041 (3) | 0.0330 (4) | |
O3 | 0.7557 (2) | 0.80730 (16) | 0.6260 (4) | 0.0559 (7) | |
O4 | 0.63483 (15) | 0.69485 (15) | 0.8490 (3) | 0.0367 (5) | |
H4O | 0.6365 | 0.7465 | 0.9133 | 0.044* | |
O1 | 0.74921 (14) | 0.46921 (14) | 0.8890 (3) | 0.0308 (4) | |
C1 | 0.7503 (2) | 0.5512 (2) | 0.8267 (4) | 0.0247 (5) | |
C2 | 0.68666 (19) | 0.5418 (2) | 0.6313 (4) | 0.0235 (5) | |
C3 | 0.6077 (2) | 0.4408 (2) | 0.3371 (4) | 0.0278 (6) | |
H3A | 0.5820 | 0.3758 | 0.2631 | 0.033* | |
C4 | 0.5971 (2) | 0.5207 (2) | 0.2472 (4) | 0.0321 (6) | |
H4A | 0.5686 | 0.5128 | 0.1095 | 0.039* | |
C5 | 0.6284 (2) | 0.6119 (2) | 0.3589 (4) | 0.0329 (6) | |
H5A | 0.6206 | 0.6676 | 0.3002 | 0.039* | |
C6 | 0.6715 (2) | 0.6227 (2) | 0.5585 (4) | 0.0249 (5) | |
C7 | 0.6941 (2) | 0.7188 (2) | 0.6845 (4) | 0.0296 (6) | |
N1S | 0.9175 (4) | 1.0138 (4) | 0.7528 (8) | 0.0448 (11) | 0.65 |
C1S | 1.0000 | 1.0000 | 0.7526 (11) | 0.0393 (18) | 0.65 |
H1SA | 0.9332 | 1.0779 | 0.7247 | 0.047* | |
H1SB | 0.8556 | 0.9641 | 0.7169 | 0.047* | |
Zn2 | 1.0000 | 1.0000 | 1.0000 | 0.0402 (6)* | 0.35 |
O1S | 0.8856 (7) | 1.0091 (8) | 0.8232 (14) | 0.057 (3)* | 0.35 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn1 | 0.0236 (2) | 0.0236 (2) | 0.0317 (3) | 0.01181 (11) | 0.000 | 0.000 |
N1 | 0.0240 (11) | 0.0250 (12) | 0.0270 (10) | 0.0144 (10) | −0.0022 (8) | −0.0029 (8) |
O2 | 0.0314 (10) | 0.0266 (10) | 0.0415 (10) | 0.0148 (9) | −0.0141 (8) | −0.0112 (8) |
O3 | 0.0712 (17) | 0.0240 (12) | 0.0586 (14) | 0.0133 (12) | 0.0215 (12) | 0.0021 (10) |
O4 | 0.0365 (12) | 0.0287 (11) | 0.0448 (11) | 0.0161 (9) | 0.0097 (9) | −0.0063 (9) |
O1 | 0.0356 (11) | 0.0242 (10) | 0.0330 (10) | 0.0152 (9) | −0.0097 (8) | −0.0006 (7) |
C1 | 0.0204 (13) | 0.0282 (14) | 0.0262 (12) | 0.0125 (11) | 0.0000 (9) | −0.0028 (10) |
C2 | 0.0192 (13) | 0.0235 (13) | 0.0262 (11) | 0.0095 (11) | 0.0008 (10) | −0.0019 (10) |
C3 | 0.0267 (14) | 0.0295 (14) | 0.0289 (13) | 0.0153 (12) | −0.0049 (10) | −0.0076 (10) |
C4 | 0.0330 (15) | 0.0404 (17) | 0.0274 (13) | 0.0216 (14) | −0.0070 (11) | −0.0027 (11) |
C5 | 0.0371 (16) | 0.0323 (16) | 0.0376 (14) | 0.0236 (14) | −0.0031 (12) | 0.0033 (12) |
C6 | 0.0229 (13) | 0.0235 (13) | 0.0300 (12) | 0.0128 (11) | 0.0023 (10) | 0.0004 (10) |
C7 | 0.0301 (15) | 0.0278 (15) | 0.0345 (14) | 0.0172 (13) | −0.0023 (11) | −0.0009 (11) |
N1S | 0.039 (3) | 0.036 (3) | 0.055 (3) | 0.015 (2) | −0.010 (2) | −0.001 (2) |
C1S | 0.038 (3) | 0.038 (3) | 0.042 (4) | 0.0189 (14) | 0.000 | 0.000 |
Zn1—O1i | 2.0818 (18) | C4—H4A | 0.9500 |
Zn1—O1 | 2.0818 (18) | C5—C6 | 1.388 (4) |
Zn1—O1ii | 2.0818 (18) | C5—H5A | 0.9500 |
Zn1—N1i | 2.164 (2) | C6—C7 | 1.500 (4) |
Zn1—N1ii | 2.164 (2) | N1S—C1S | 1.314 (5) |
Zn1—N1 | 2.164 (2) | N1S—H1SA | 0.8635 |
N1—C3 | 1.332 (3) | N1S—H1SB | 0.8592 |
N1—C2 | 1.337 (3) | C1S—N1Siii | 1.314 (5) |
O2—C1 | 1.252 (3) | C1S—N1Siv | 1.314 (5) |
O3—C7 | 1.204 (3) | Zn2—O1Sv | 2.069 (10) |
O4—C7 | 1.288 (3) | Zn2—O1Siii | 2.069 (10) |
O4—H4O | 0.8453 | Zn2—O1Svi | 2.069 (10) |
O1—C1 | 1.252 (3) | Zn2—O1S | 2.069 (10) |
C1—C2 | 1.514 (3) | Zn2—O1Svii | 2.069 (10) |
C2—C6 | 1.383 (3) | Zn2—O1Siv | 2.069 (10) |
C3—C4 | 1.374 (4) | O1S—H1SA | 1.0872 |
C3—H3A | 0.9500 | O1S—H1SB | 0.8897 |
C4—C5 | 1.369 (4) | ||
O1i—Zn1—O1 | 91.96 (7) | C4—C5—H5A | 120.2 |
O1i—Zn1—O1ii | 91.96 (7) | C6—C5—H5A | 120.2 |
O1—Zn1—O1ii | 91.96 (7) | C2—C6—C5 | 117.7 (2) |
O1i—Zn1—N1i | 77.27 (7) | C2—C6—C7 | 124.3 (2) |
O1—Zn1—N1i | 98.26 (8) | C5—C6—C7 | 117.9 (2) |
O1ii—Zn1—N1i | 165.33 (7) | O3—C7—O4 | 125.5 (3) |
O1i—Zn1—N1ii | 98.26 (8) | O3—C7—C6 | 122.3 (2) |
O1—Zn1—N1ii | 165.33 (7) | O4—C7—C6 | 112.1 (2) |
O1ii—Zn1—N1ii | 77.27 (7) | C1S—N1S—H1SA | 113.5 |
N1i—Zn1—N1ii | 94.25 (7) | C1S—N1S—H1SB | 121.8 |
O1i—Zn1—N1 | 165.33 (8) | H1SA—N1S—H1SB | 117.1 |
O1—Zn1—N1 | 77.27 (7) | N1Siii—C1S—N1Siv | 120.000 (7) |
O1ii—Zn1—N1 | 98.26 (8) | N1Siii—C1S—N1S | 120.000 (4) |
N1i—Zn1—N1 | 94.25 (7) | N1Siv—C1S—N1S | 120.000 (11) |
N1ii—Zn1—N1 | 94.25 (7) | O1Sv—Zn2—O1Siii | 86.7 (3) |
C3—N1—C2 | 119.1 (2) | O1Sv—Zn2—O1Svi | 93.3 (3) |
C3—N1—Zn1 | 128.38 (18) | O1Siii—Zn2—O1Svi | 86.7 (3) |
C2—N1—Zn1 | 112.24 (15) | O1Sv—Zn2—O1S | 180.000 (2) |
C7—O4—H4O | 115.7 | O1Siii—Zn2—O1S | 93.3 (3) |
C1—O1—Zn1 | 117.25 (15) | O1Svi—Zn2—O1S | 86.7 (3) |
O1—C1—O2 | 125.7 (2) | O1Sv—Zn2—O1Svii | 93.3 (3) |
O1—C1—C2 | 117.3 (2) | O1Siii—Zn2—O1Svii | 180.0 (6) |
O2—C1—C2 | 116.9 (2) | O1Svi—Zn2—O1Svii | 93.3 (3) |
N1—C2—C6 | 122.2 (2) | O1S—Zn2—O1Svii | 86.7 (3) |
N1—C2—C1 | 114.3 (2) | O1Sv—Zn2—O1Siv | 86.7 (3) |
C6—C2—C1 | 123.3 (2) | O1Siii—Zn2—O1Siv | 93.3 (3) |
N1—C3—C4 | 122.0 (2) | O1Svi—Zn2—O1Siv | 180.0 (3) |
N1—C3—H3A | 119.0 | O1S—Zn2—O1Siv | 93.3 (3) |
C4—C3—H3A | 119.0 | O1Svii—Zn2—O1Siv | 86.7 (3) |
C5—C4—C3 | 119.0 (2) | Zn2—O1S—H1SA | 102.1 |
C5—C4—H4A | 120.5 | Zn2—O1S—H1SB | 118.7 |
C3—C4—H4A | 120.5 | H1SA—O1S—H1SB | 95.5 |
C4—C5—C6 | 119.7 (2) | ||
O1i—Zn1—N1—C3 | 133.0 (3) | Zn1—N1—C2—C1 | 14.2 (3) |
O1—Zn1—N1—C3 | 176.6 (2) | O1—C1—C2—N1 | −12.2 (3) |
O1ii—Zn1—N1—C3 | −93.3 (2) | O2—C1—C2—N1 | 163.7 (2) |
N1i—Zn1—N1—C3 | 79.05 (17) | O1—C1—C2—C6 | 172.7 (2) |
N1ii—Zn1—N1—C3 | −15.5 (2) | O2—C1—C2—C6 | −11.4 (4) |
O1i—Zn1—N1—C2 | −53.4 (4) | C2—N1—C3—C4 | 1.5 (4) |
O1—Zn1—N1—C2 | −9.84 (16) | Zn1—N1—C3—C4 | 174.73 (19) |
O1ii—Zn1—N1—C2 | 80.30 (17) | N1—C3—C4—C5 | −3.8 (4) |
N1i—Zn1—N1—C2 | −107.4 (2) | C3—C4—C5—C6 | 1.0 (4) |
N1ii—Zn1—N1—C2 | 158.04 (18) | N1—C2—C6—C5 | −6.1 (4) |
O1i—Zn1—O1—C1 | 173.28 (19) | C1—C2—C6—C5 | 168.6 (2) |
O1ii—Zn1—O1—C1 | −94.7 (2) | N1—C2—C6—C7 | 171.1 (2) |
N1i—Zn1—O1—C1 | 95.86 (19) | C1—C2—C6—C7 | −14.2 (4) |
N1ii—Zn1—O1—C1 | −52.4 (4) | C4—C5—C6—C2 | 3.7 (4) |
N1—Zn1—O1—C1 | 3.33 (18) | C4—C5—C6—C7 | −173.7 (3) |
Zn1—O1—C1—O2 | −172.2 (2) | C2—C6—C7—O3 | 121.4 (3) |
Zn1—O1—C1—C2 | 3.2 (3) | C5—C6—C7—O3 | −61.4 (4) |
C3—N1—C2—C6 | 3.6 (4) | C2—C6—C7—O4 | −63.4 (3) |
Zn1—N1—C2—C6 | −170.68 (19) | C5—C6—C7—O4 | 113.8 (3) |
C3—N1—C2—C1 | −171.6 (2) |
Symmetry codes: (i) −x+y+1, −x+1, z; (ii) −y+1, x−y, z; (iii) −x+y+1, −x+2, z; (iv) −y+2, x−y+1, z; (v) −x+2, −y+2, −z+2; (vi) y, −x+y+1, −z+2; (vii) x−y+1, x, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1S—H1SA···O3iii | 0.86 | 2.25 | 3.032 (6) | 150 |
N1S—H1SB···O3 | 0.86 | 2.09 | 2.859 (6) | 149 |
O4—H4O···O1vi | 0.85 | 2.59 | 3.101 (3) | 120 |
O4—H4O···O2vi | 0.85 | 1.73 | 2.563 (3) | 167 |
Symmetry codes: (iii) −x+y+1, −x+2, z; (vi) y, −x+y+1, −z+2. |
Experimental details
Crystal data | |
Chemical formula | (CH6N3)1.30[Zn(H2O)6]0.35[Zn(C7H4NO4)3]2 |
Mr | 1266.24 |
Crystal system, space group | Trigonal, P3 |
Temperature (K) | 120 |
a, c (Å) | 14.5775 (16), 6.3506 (16) |
V (Å3) | 1168.7 (3) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 1.31 |
Crystal size (mm) | 0.25 × 0.25 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 1998) |
Tmin, Tmax | 0.731, 0.773 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4304, 2079, 1443 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.681 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.106, 1.00 |
No. of reflections | 2079 |
No. of parameters | 129 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.88, −0.69 |
Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 1998), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1S—H1SA···O3i | 0.86 | 2.25 | 3.032 (6) | 150 |
N1S—H1SB···O3 | 0.86 | 2.09 | 2.859 (6) | 149 |
O4—H4O···O1ii | 0.85 | 2.59 | 3.101 (3) | 120 |
O4—H4O···O2ii | 0.85 | 1.73 | 2.563 (3) | 167 |
Symmetry codes: (i) −x+y+1, −x+2, z; (ii) y, −x+y+1, −z+2. |
Acknowledgements
The authors express their deepest appreciation to the late Professor Dr. H. Aghabozorg who inspired, advised and assisted during this study.
References
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Tabatabaee, M., Razavimahmoudabadi, V., Kukovec, B.-M., Ghassemzadeh, M. & Neumüller, B. (2011). J. Inorg. Organomet. Polym. 21, 450–457. Web of Science CSD CrossRef CAS Google Scholar
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Unlike pyridine-2,6-dicarboxylic acid, which is an O,N,O-tridentate ligand (e.g. Tabatabaee, Abbasi et al., 2011), pyridine-2,3-dicarboxylic acid often acts as a bidentate chelating ligand through nitrogen and one oxygen atom of the 2-position carboxylic group, while the 3-position carboxylate oxygen atom can act as a bridging atom between metal ions to form a coordination polymer. Recently, we have reported the synthesis and characterization of two one-dimensional coordination polymers of Cd2+ and Co2+ with pyridine-2,3-dicarboxylic acid (2,3-H2pydc) (Tabatabaee, Razavimahmoudabadi et al., 2011) and in this study we wish to report the crystal structure of a mononuclear Zn(II) complex with (2,3-H2pydc) in the presence of guanidine hydrochloride.
The title compound consists of [Zn(2,3-Hpydc)3]- anions, (GH)+ and [Zn(H2O)6]2+ cations (Fig. 1). Two variant of [Zn(2,3-pydcH)3]- anions exist in 1 and to balance the charges, one protonated guanidinium cation and [Zn(H2O)6]2+ are present in 1.30: 0.35 ratio. Zn(II) ion in the title compound is six-coordinated by three (2,3-pydcH)2– anions in O,N-bidentate fashion and the geometry of the resulting ZnN3O3 coordination can be described as distorted octahedral. The bond angles around Zn(II) ion involving trans pairs of donor atoms are 165.33 (7) and for the cis pairs of donor atoms are in the range of 77.27 (7)– 98.26 (8)°. The bond distances Zn–N and Zn–O in are in accordance with those in related structures (Tabatabaee, Razavimahmoudabadi et al., 2011).
There is some hydrogen bonding interactions such as O—H···O, N—H···O between cations and anions. As was shown in figure 2, Hydrogen bonding interactions contribute to the formation of a two dimensional network cavity structure. There is also π-π stacking interactions between the aromatic rings defined by atoms N1/C2 /C6/C5/C4/C3 [symmetry code: 1-X,1-Y,1-Z; centroid-centroid distance 3.797 (8) Å; the angle between the planes 0°; the perpendicular distance between the planes 3.588 Å; the slippage 1.24 Å]. Ion pairing, hydrogen bonding, π–π stacking and van der Waals interactions are also effective for packing of the crystal structure (Fig 3).