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The crystal structure of the title compound, [Zn-(C7H5O2)2(C5H6N2)2], is built of monomeric [Zn(2-apy)2(OBz)2] mol­ecules (apy is amino­pyridine and OBz is benzoate). The Zn atom lies on a twofold symmetry axis and adopts a slightly distorted tetrahedral coordination. The Zn...O distances to the non-coordinated O atoms are long at 2.872 (3) Å. Each non-ligating carbonyl O atom of the benzoate anion accepts one intramolecular and one intermolecular hydrogen bond from the amino group. The mol­ecules form a chain along the c axis through intermolecular N—H...O hydrogen bonds between the amino and carboxyl groups.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100003462/na1461sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100003462/na1461Isup2.hkl
Contains datablock I

CCDC reference: 147603

Comment top

Zinc is a relatively abundant element in biological organisms and plays an essential role in a large number of enzymatic reactions (Liljas et al., 1972). Zinc(II), being a d10 ion, gives a UV-visible spectrum which does not provide information on its structure. The structure of the zinc binding site could be elucidated by X-ray crystallography. The number of reports on monomeric zinc complexes containing carboxylate and basic ligands are quite limited. In this paper, we report the crystal structure of the title compound, bis(2-aminopyridine-N)bis(benzoato-O)zinc, (I), which has been determined in an attempt to understand the structural behaviour of nitrogen-containing ligands when coordinating to zinc carboxylates.

The Zn atom in the central ZnO2N2 system is in a slightly deformed tetrahedral coordination formed by two benzoate anions and two 2-aminopyridine molecules. The bond lengths in the coordination polyhedron are normal. The Zn—N bond distance of 2.052 (4) Å is in accord with similar distances reported previously, e.g. 2.039 (8) Å in [ZnCl2(C17H19N3)2] (Parvez & Rusiewicz, 1995) and 2.056 (4) Å in [Zn(C5H7NO2)2] (Ng et al., 1995), and the Zn—O distance of 1.930 (3) Å is a little shorter than similar reported distances, e.g. 1.959 (3) Å in [Zn(C3H5O2)2(CH4N2S)2] (Smolander et al., 1994) and 1.963 (2) Å in [Zn(C7H5O2)2(CH4N2S)2] (Cernak et al. 1995). Two additional Zn···O interactions to the non-coordinated O atoms of the carboxylate groups are long [2.872 (3) Å].

The deformation of the coordination polyhedron, which is centred on a twofold axis, mainly involves the two angles bisected by that axis, i.e. O1—Zn—O1i, widened to 127.9 (2)°, and N2—Zn—N2i, narrowed to 100.6 (2)° [symmetry code: (i) 1 − x, y, 1/2 − z]. This appears to be due to steric effects as shown by the two non-bonded contacts C12···N2i = 3.422 (6) and O2···O1i = 3.393 (7) Å. Some influence is also excerted by the intramolecular N1—H···O1 hydrogen bond on the N2···O1 [3.128 (5) Å] contact. This is different from the corresponding value in similar complexes containing the ZnO2N2 unit, which exhibit one short and one long additional interaction, e.g. 2.645 (2), 3.034 (2) Å and 118.5 (1)° in Zn(CH3COO)2(im)2 (im is imidazole), and 2.692 (2), 3.151 (2) Å and 116.3 (1)° in Zn(CH3CH2COO)2(im)2 (Horrocks et al., 1982).

As expected, the C—O bond lengths [1.274 (5) Å] of the coordinated O atoms are somewhat longer than those of the non-ligating O atoms [1.213 (6) Å]. The latter suggests more double-bond character for the C—O bond (Davey & Stephens, 1971). The average C—C distance [1.375 (7) Å] in the phenyl ring agrees well with the value [1.380 (16) Å] reported by Allen et al. (1987). The 2-aminopyridine ligand is planar and coordinates so that the zinc ion lie nears the plane. Thus, the carboxylate and its mode of coordination appear to be entirely normal. The molecules form a chain along the c axis through intermolecular N—H···O hydrogen bonds between the amino and carboxyl groups. The distance between the ring centroids involve symmetry related ligands, i.e. Cgpyr···Cgar(1 − x, 1 − y, −z) is 3.821 (1) Å.

Experimental top

The title compound was prepared by dissolving zinc dibenzoate (0.03 mmol) in EtOH (80 ml) followed by the addition of 2-aminopyridine (0.06 mmol). The solution was heated to boiling until all the solid dissolved and was then filtered. The filtrate allowed to stand at room temperature for two weeks. over which time colorless prismatic crystals formed on slow evaporation of the solvent.

Refinement top

The maximum and minimum residual electron densities were located at 0.90 and 0.82 Å, respectively, from Zn1 atom.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).

Figures top
[Figure 1] Fig. 1. The molecular structure of title compound showing 30% probability displacement ellipsoids and the atom-numbering scheme.
Bis(2-aminopyridine-N)zinc dibenzoate top
Crystal data top
[Zn(C7H5O2)2(C5H6N2)2]F(000) = 1024
Mr = 495.83Dx = 1.47 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 20.3597 (7) ÅCell parameters from 6408 reflections
b = 9.9400 (3) Åθ = 2.2–28.4°
c = 12.0064 (4) ŵ = 1.13 mm1
β = 112.336 (1)°T = 293 K
V = 2247.49 (13) Å3Slab, colourless
Z = 40.44 × 0.22 × 0.12 mm
Data collection top
Siemens SMART CCD area-detector
diffractometer
2785 independent reflections
Radiation source: fine-focus sealed tube2151 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.072
Detector resolution: 8.33 pixels mm-1θmax = 28.6°, θmin = 2.2°
ω scansh = 2527
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
k = 1311
Tmin = 0.636, Tmax = 0.876l = 1613
7990 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.061Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.111H-atom parameters constrained
S = 1.11 w = 1/[σ2(Fo2) + (0.1089P)2 + 3.736P]
where P = (Fo2 + 2Fc2)/3
2785 reflections(Δ/σ)max < 0.001
150 parametersΔρmax = 1.24 e Å3
0 restraintsΔρmin = 0.86 e Å3
Crystal data top
[Zn(C7H5O2)2(C5H6N2)2]V = 2247.49 (13) Å3
Mr = 495.83Z = 4
Monoclinic, C2/cMo Kα radiation
a = 20.3597 (7) ŵ = 1.13 mm1
b = 9.9400 (3) ÅT = 293 K
c = 12.0064 (4) Å0.44 × 0.22 × 0.12 mm
β = 112.336 (1)°
Data collection top
Siemens SMART CCD area-detector
diffractometer
2785 independent reflections
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
2151 reflections with I > 2σ(I)
Tmin = 0.636, Tmax = 0.876Rint = 0.072
7990 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0610 restraints
wR(F2) = 0.111H-atom parameters constrained
S = 1.11Δρmax = 1.24 e Å3
2785 reflectionsΔρmin = 0.86 e Å3
150 parameters
Special details top

Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 30 s covered 0.3° in ω. The crystal-to-detector distance was 4 cm and the detector swing angle was −35°. Coverage of the unique set is over 97% complete. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the duplicate reflections, and was found to be negligible.

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 (Å2) top
xyzUiso*/Ueq
Zn10.50000.33837 (6)0.25000.0338 (3)
O10.57702 (17)0.4235 (3)0.2205 (3)0.0466 (8)
O20.5861 (3)0.5662 (5)0.3639 (5)0.0825 (15)
N10.5123 (3)0.3026 (5)0.0102 (4)0.0614 (13)
H1A0.53300.35920.04650.074*
H1B0.51950.30610.07630.074*
N20.4589 (2)0.2065 (4)0.1088 (3)0.0385 (8)
C10.6032 (2)0.5284 (5)0.2826 (4)0.0418 (10)
C20.6593 (2)0.6006 (4)0.2546 (4)0.0385 (9)
C30.7037 (3)0.6896 (6)0.3380 (6)0.0615 (15)
H3A0.69860.70360.41090.074*
C40.7553 (4)0.7570 (6)0.3133 (8)0.082 (2)
H4A0.78580.81510.37030.098*
C50.7622 (3)0.7394 (6)0.2048 (8)0.078 (2)
H5A0.79670.78700.18800.093*
C60.7189 (3)0.6527 (5)0.1221 (7)0.0659 (17)
H6A0.72410.64010.04910.079*
C70.6668 (3)0.5829 (5)0.1462 (5)0.0448 (10)
H7A0.63690.52410.08910.054*
C80.4688 (2)0.2089 (5)0.0043 (4)0.0413 (9)
C90.4328 (3)0.1201 (6)0.0886 (5)0.0562 (13)
H9A0.43950.12400.16090.067*
C100.3883 (3)0.0291 (6)0.0734 (6)0.0657 (16)
H10A0.36440.03090.13490.079*
C110.3782 (3)0.0247 (6)0.0346 (7)0.0701 (17)
H11A0.34780.03800.04710.084*
C120.4138 (3)0.1141 (6)0.1207 (5)0.0559 (13)
H12A0.40670.11180.19270.067*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.0376 (4)0.0347 (4)0.0359 (4)0.0000.0215 (3)0.000
O10.0492 (18)0.0458 (17)0.054 (2)0.0115 (14)0.0301 (16)0.0065 (15)
O20.099 (3)0.096 (3)0.079 (3)0.021 (3)0.064 (3)0.030 (3)
N10.080 (3)0.073 (3)0.049 (3)0.031 (3)0.045 (3)0.017 (2)
N20.046 (2)0.0341 (17)0.039 (2)0.0039 (15)0.0209 (17)0.0010 (14)
C10.045 (2)0.046 (2)0.042 (2)0.0040 (19)0.024 (2)0.0067 (19)
C20.039 (2)0.031 (2)0.045 (2)0.0035 (16)0.0158 (19)0.0004 (17)
C30.064 (3)0.052 (3)0.059 (3)0.017 (3)0.014 (3)0.009 (2)
C40.063 (4)0.060 (4)0.101 (6)0.029 (3)0.006 (4)0.003 (4)
C50.052 (3)0.059 (4)0.123 (6)0.014 (3)0.033 (4)0.023 (4)
C60.067 (4)0.057 (3)0.092 (5)0.002 (3)0.051 (4)0.018 (3)
C70.048 (2)0.040 (2)0.055 (3)0.0006 (19)0.028 (2)0.0013 (19)
C80.045 (2)0.042 (2)0.039 (2)0.0040 (19)0.018 (2)0.0007 (18)
C90.066 (3)0.058 (3)0.043 (3)0.008 (3)0.019 (3)0.010 (2)
C100.068 (4)0.056 (3)0.063 (4)0.005 (3)0.013 (3)0.022 (3)
C110.070 (4)0.055 (3)0.086 (5)0.027 (3)0.030 (3)0.011 (3)
C120.066 (3)0.053 (3)0.058 (3)0.013 (3)0.034 (3)0.000 (2)
Geometric parameters (Å, º) top
Zn1—O11.930 (3)C4—C51.373 (11)
Zn1—O1i1.930 (3)C4—H4A0.9300
Zn1—N22.052 (4)C5—C61.357 (11)
Zn1—N2i2.052 (4)C5—H5A0.9300
O1—C11.274 (5)C6—C71.386 (7)
O2—C11.213 (6)C6—H6A0.9300
N1—C81.342 (6)C7—H7A0.9300
N1—H1A0.8600C8—C91.393 (7)
N1—H1B0.8600C9—C101.340 (8)
N2—C81.345 (6)C9—H9A0.9300
N2—C121.344 (6)C10—C111.389 (9)
C1—C21.493 (6)C10—H10A0.9300
C2—C71.378 (7)C11—C121.347 (8)
C2—C31.383 (7)C11—H11A0.9300
C3—C41.370 (9)C12—H12A0.9300
C3—H3A0.9300
O1—Zn1—O1i127.9 (2)C6—C5—C4120.2 (5)
O1—Zn1—N2103.5 (1)C6—C5—H5A119.9
O1i—Zn1—N2109.1 (2)C4—C5—H5A119.9
O1—Zn1—N2i109.1 (2)C5—C6—C7120.1 (7)
O1i—Zn1—N2i103.5 (1)C5—C6—H6A119.9
N2—Zn1—N2i100.6 (2)C7—C6—H6A119.9
C1—O1—Zn1116.0 (3)C2—C7—C6120.0 (5)
C8—N1—H1A120.0C2—C7—H7A120.0
C8—N1—H1B120.0C6—C7—H7A120.0
H1A—N1—H1B120.0N1—C8—N2118.3 (4)
C8—N2—C12117.5 (4)N1—C8—C9120.5 (5)
C8—N2—Zn1126.9 (3)N2—C8—C9121.1 (5)
C12—N2—Zn1115.4 (3)C10—C9—C8119.8 (5)
O2—C1—O1122.7 (4)C10—C9—H9A120.1
O2—C1—C2120.7 (4)C8—C9—H9A120.1
O1—C1—C2116.5 (4)C9—C10—C11119.7 (5)
C7—C2—C3119.3 (5)C9—C10—H10A120.1
C7—C2—C1121.3 (4)C11—C10—H10A120.1
C3—C2—C1119.3 (5)C12—C11—C10117.9 (5)
C4—C3—C2119.9 (7)C12—C11—H11A121.0
C4—C3—H3A120.0C10—C11—H11A121.0
C2—C3—H3A120.0N2—C12—C11124.0 (5)
C3—C4—C5120.4 (6)N2—C12—H12A118.0
C3—C4—H4A119.8C11—C12—H12A118.0
C5—C4—H4A119.8
O1i—Zn1—O1—C139.3 (3)C2—C3—C4—C51.6 (10)
N2—Zn1—O1—C1167.1 (3)C3—C4—C5—C61.4 (11)
N2i—Zn1—O1—C186.4 (4)C4—C5—C6—C70.8 (10)
O1—Zn1—N2—C817.9 (4)C3—C2—C7—C60.7 (7)
O1i—Zn1—N2—C8120.9 (4)C1—C2—C7—C6179.2 (5)
N2i—Zn1—N2—C8130.7 (4)C5—C6—C7—C20.5 (8)
O1—Zn1—N2—C12166.7 (4)C12—N2—C8—N1178.4 (5)
O1i—Zn1—N2—C1254.5 (4)Zn1—N2—C8—N13.1 (6)
N2i—Zn1—N2—C1253.9 (4)C12—N2—C8—C91.0 (7)
Zn1—O1—C1—O27.0 (7)Zn1—N2—C8—C9174.4 (4)
Zn1—O1—C1—C2175.9 (3)N1—C8—C9—C10178.5 (5)
O2—C1—C2—C7162.9 (5)N2—C8—C9—C101.1 (8)
O1—C1—C2—C719.9 (7)C8—C9—C10—C110.4 (9)
O2—C1—C2—C315.6 (8)C9—C10—C11—C120.4 (10)
O1—C1—C2—C3161.6 (5)C8—N2—C12—C110.1 (9)
C7—C2—C3—C41.2 (9)Zn1—N2—C12—C11175.8 (5)
C1—C2—C3—C4179.7 (5)C10—C11—C12—N20.6 (10)
Symmetry code: (i) x+1, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O10.862.042.842 (6)155
N1—H1B···O2ii0.862.172.823 (8)133
Symmetry code: (ii) x, y+1, z1/2.

Experimental details

Crystal data
Chemical formula[Zn(C7H5O2)2(C5H6N2)2]
Mr495.83
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)20.3597 (7), 9.9400 (3), 12.0064 (4)
β (°) 112.336 (1)
V3)2247.49 (13)
Z4
Radiation typeMo Kα
µ (mm1)1.13
Crystal size (mm)0.44 × 0.22 × 0.12
Data collection
DiffractometerSiemens SMART CCD area-detector
diffractometer
Absorption correctionEmpirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.636, 0.876
No. of measured, independent and
observed [I > 2σ(I)] reflections
7990, 2785, 2151
Rint0.072
(sin θ/λ)max1)0.673
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.061, 0.111, 1.11
No. of reflections2785
No. of parameters150
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.24, 0.86

Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT, SHELXTL (Sheldrick, 1997), SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).

Selected geometric parameters (Å, º) top
Zn1—O11.930 (3)N1—C81.342 (6)
Zn1—N22.052 (4)N2—C81.345 (6)
O1—C11.274 (5)N2—C121.344 (6)
O2—C11.213 (6)
O1—Zn1—O1i127.9 (2)C1—O1—Zn1116.0 (3)
O1—Zn1—N2103.5 (1)C8—N2—Zn1126.9 (3)
O1i—Zn1—N2109.1 (2)C12—N2—Zn1115.4 (3)
Symmetry code: (i) x+1, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O10.862.042.842 (6)155
N1—H1B···O2ii0.862.172.823 (8)133
Symmetry code: (ii) x, y+1, z1/2.
 

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