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Acta Cryst. (2007). E63, m3008    [ doi:10.1107/S1600536807056589 ]

Bis([mu]-4-formyl-2-methoxyphenolato)bis[aquachloridozinc(II)] dihydrate

H.-M. Guo, H.-D. Xian and G.-L. Zhao

Abstract top

In the centrosymmetric dinuclear molecule of the title compound, [Zn2(C8H7O3)2Cl2(H2O)2], the Zn ions are bridged by two phenolate O atoms, with a Zn...Zn distance of 3.1216 (6) Å, forming a Zn2O2 four-membered ring. Each Zn coordination is completed by a further bidentate 4-hydroxy-3-methoxybenzaldehyde ion, one chloride ion and one water molecule. The water molecules are involved in hydrogen bonds, which stabilize the crystal structure.

Comment top

In recent years, phenolic compounds have attracted the interest of researchers because they show promise of being powerful antioxidants that can protect the human body from free radicals (Rice-Evans et al., 1996). Their complexes are becoming increasingly important as biochemical, analytical and antimicrobial reagents (Tumer et al., 1999). We report here the zinc dinuclear vanillin complex bis[aqua-chloro-(4-hydroxy-3-methoxybenzaldehyde)-zinc(II)] dihydrate (I).

The structural features of the I dimer shown in Fig. 1. The complex is centrosymmetric with an inversion center in the middle of the Zn2O2 core. Similar binuclear zinc(II) phenol O-bridged complexes with a planar Zn2O2 core have been reported by Olmstead et al., (1991) and Kunert et al., (2000). Each Zn atom employs one oxygen donor - O1, from the vanillin ligands to form the Zn2O2 unit, while the second oxygen atom, O2, from this bridging vanillin ligand is terminally coordinated to the Zn atom. This complex contains a central four-membered Zn—O—Zn—O ring can be described as parallelogram. The atom O1 as a bridge atom coordinate with two Zn atoms. The Zn—O bond lengths of the terminal bonds (Zn1—O2 = 2.2907 (17) Å) are significantly larger than the bridging Zn—O—Zn moiety (Zn1—O1 = 1.9851 (17) Å, Zn1—O1A = 2.0349 (16) Å) but still less than the Zn—O bond length (2.444 Å) reported by Ding et al., (2005). The coordinated water molecules and chloride ion are located trans with respect to the Zn2O2 plane. The bridging vanillin ligands are coplanar. There are two water molecules in the lattice. The O1w H atoms make intermolecular hydrogen bonds to the O2w atoms [(symmetry code: −1 + x, y, z) with d(O···O) = 2.671 (3)Å and angle O–H···O = 175.(3)°] and uncoordinated O3 atoms [(symmetry code: x − 1, y, z − 1) with d(O···O) = 2.666 (3)Å and angle O–H···O = 170.(4)°]. The O2w H atoms also make intermolecular hydrogen bonds to the Cl atoms [(symmetry code: 1/2 + x, 0.5 − y, 1/2 + z) with d(O···O) = 3.259 (3)Å and angle O–H···O = 178.(4)°]. The vanillin O atoms, the water O atoms and chloride ion contribute to the formation of a hydrogen-bonded three-dimensional network.

Related literature top

For related crystal structures, see: Ding et al. (2005); Kunert et al. (2000); Olmstead et al. (1991). For common applications of these complexes, see: Rice-Evans et al. (1996); Tumer et al. (1999).

Experimental top

ZnCl2(1 mmol, 136 mg), 2-methoxy-4-[(4-nitrophenylimino)methyl]phenol (2 mmol, 545 mg) were dissolved in ethanol (25 ml) solution and the mixture was stirred for 2 h at room temperature. The yellow solution was kept aside, and the orange crystal was abtained after several weeks.

Refinement top

The H atoms bonded to C atoms were positioned geometrically and refined using a riding model: aromatic C–H = 0.93Å and aliphatic C–H = 0.96 Å, Uiso(H) = 1.2Ueq(C) for aromatic and Uiso(H) = 1.5Ueq(C) for aliphatic. The H atoms bonded to O atoms were located in a difference Fourier maps and refined with O–H distance restraints of 0.85 (2) and Uiso(H) = 1.5Ueq(O).

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2002); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The molecular structure of I, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as a spheres of arbitrary radius.
Bis(µ-4-formyl-2-methoxyphenolato)bis[aquachloridozinc(II)] dihydrate top
Crystal data top
[Zn2(C8H7O3)2Cl2(H2O)2]F000 = 584
Mr = 576.02Dx = 1.750 Mg m−3
Monoclinic, P21/nMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 3431 reflections
a = 7.0896 (6) Åθ = 2.5–27.5º
b = 15.9772 (10) ŵ = 2.49 mm−1
c = 10.1193 (7) ÅT = 296 (2) K
β = 107.559 (4)ºPlate, orange
V = 1092.83 (14) Å30.26 × 0.17 × 0.07 mm
Z = 2
Data collection top
Bruker P4
diffractometer		2500 independent reflections
Radiation source: Fine-focus sealed tube2046 reflections with I > 2σ(I)
Monochromator: GraphiteRint = 0.028
T = 296(2) Kθmax = 27.5º
ω–scansθmin = 2.5º
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −9→8
Tmin = 0.517, Tmax = 0.840k = −20→20
9933 measured reflectionsl = −13→12
Refinement top
Refinement on F2Secondary atom site location: Difmap
Least-squares matrix: FullHydrogen site location: Geom
R[F2 > 2σ(F2)] = 0.030H atoms treated by a mixture of
independent and constrained refinement
wR(F2) = 0.088  w = 1/[σ2(Fo2) + (0.0464P)2 + 0.539P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
2500 reflectionsΔρmax = 0.57 e Å−3
148 parametersΔρmin = −0.48 e Å−3
6 restraintsExtinction correction: None
Primary atom site location: Direct
Crystal data top
[Zn2(C8H7O3)2Cl2(H2O)2]V = 1092.83 (14) Å3
Mr = 576.02Z = 2
Monoclinic, P21/nMo Kα
a = 7.0896 (6) ŵ = 2.49 mm−1
b = 15.9772 (10) ÅT = 296 (2) K
c = 10.1193 (7) Å0.26 × 0.17 × 0.07 mm
β = 107.559 (4)º
Data collection top
Bruker P4
diffractometer		2500 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		2046 reflections with I > 2σ(I)
Tmin = 0.517, Tmax = 0.840Rint = 0.028
9933 measured reflectionsStandard reflections: none
Refinement top
R[F2 > 2σ(F2)] = 0.0306 restraints
wR(F2) = 0.088H atoms treated by a mixture of
independent and constrained refinement
S = 1.06Δρmax = 0.57 e Å−3
2500 reflectionsΔρmin = −0.48 e Å−3
148 parameters
Special details top

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 > 2σ(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
Zn1−0.05704 (4)0.407241 (18)0.51776 (3)0.03079 (12)
Cl10.06529 (12)0.29032 (5)0.45511 (8)0.0496 (2)
C10.1385 (3)0.50285 (15)0.7681 (2)0.0275 (5)
C20.2207 (4)0.57134 (16)0.8483 (3)0.0330 (5)
H2A0.23060.62220.80630.040*
C30.2887 (4)0.56405 (17)0.9918 (3)0.0338 (6)
H3A0.34320.61031.04550.041*
C40.2758 (4)0.48843 (16)1.0555 (2)0.0316 (5)
C50.1889 (4)0.41882 (16)0.9764 (2)0.0309 (5)
H5A0.17900.36811.01880.037*
C60.1187 (4)0.42698 (15)0.8348 (2)0.0289 (5)
C70.0128 (5)0.28292 (17)0.7989 (3)0.0460 (7)
H7A0.05870.28480.89830.055*
H7B0.09340.24480.76610.055*
H7C−0.12210.26430.76870.055*
C80.3641 (4)0.48144 (19)1.2047 (3)0.0390 (6)
H8A0.41480.52991.25340.047*
O10.0780 (3)0.50395 (10)0.63014 (17)0.0345 (4)
O1W−0.3382 (3)0.39772 (14)0.5103 (2)0.0426 (5)
H1WA−0.434 (4)0.406 (2)0.441 (3)0.064*
H1WB−0.377 (5)0.3628 (19)0.555 (3)0.064*
O20.0256 (3)0.36493 (11)0.74433 (18)0.0406 (5)
O2W0.5141 (4)0.2849 (3)0.6469 (3)0.1013 (13)
H2WA0.393 (3)0.294 (4)0.616 (5)0.152*
H2WB0.525 (8)0.265 (4)0.725 (3)0.152*
O30.3765 (3)0.41693 (14)1.2706 (2)0.0489 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.03931 (19)0.02613 (18)0.02405 (17)−0.00240 (12)0.00521 (12)0.00208 (11)
Cl10.0609 (5)0.0417 (4)0.0420 (4)0.0132 (3)0.0091 (3)−0.0052 (3)
C10.0291 (11)0.0315 (12)0.0207 (11)0.0014 (10)0.0059 (9)0.0043 (9)
C20.0396 (14)0.0289 (12)0.0303 (13)−0.0015 (11)0.0101 (11)0.0014 (10)
C30.0373 (14)0.0339 (13)0.0276 (12)0.0030 (11)0.0060 (11)−0.0051 (10)
C40.0304 (12)0.0401 (14)0.0229 (11)0.0059 (11)0.0062 (10)0.0001 (10)
C50.0330 (13)0.0341 (13)0.0243 (12)0.0017 (10)0.0067 (10)0.0070 (10)
C60.0309 (12)0.0311 (12)0.0219 (11)0.0000 (10)0.0037 (9)0.0019 (9)
C70.0607 (19)0.0308 (14)0.0410 (15)−0.0087 (13)0.0069 (14)0.0087 (12)
C80.0405 (15)0.0511 (16)0.0232 (12)0.0051 (13)0.0062 (11)−0.0026 (12)
O10.0518 (11)0.0286 (9)0.0195 (8)−0.0056 (8)0.0053 (7)0.0034 (7)
O1W0.0363 (11)0.0565 (13)0.0303 (10)−0.0027 (9)0.0031 (8)0.0117 (9)
O20.0574 (12)0.0298 (9)0.0249 (9)−0.0113 (9)−0.0020 (8)0.0053 (7)
O2W0.0647 (17)0.154 (3)0.0694 (18)−0.045 (2)−0.0035 (14)0.058 (2)
O30.0529 (13)0.0624 (14)0.0254 (10)0.0024 (10)0.0027 (9)0.0092 (9)
Geometric parameters (Å, °) top
Zn1—O1W1.978 (2)C5—C61.374 (3)
Zn1—O11.9851 (17)C5—H5A0.9300
Zn1—O1i2.0350 (16)C6—O21.375 (3)
Zn1—Cl12.2307 (8)C7—O21.435 (3)
Zn1—O22.2905 (17)C7—H7A0.9600
Zn1—Zn1i3.1216 (6)C7—H7B0.9600
C1—O11.331 (3)C7—H7C0.9600
C1—C21.382 (3)C8—O31.217 (3)
C1—C61.415 (3)C8—H8A0.9300
C2—C31.390 (4)O1—Zn1i2.0350 (16)
C2—H2A0.9300O1W—H1WA0.827 (17)
C3—C41.385 (4)O1W—H1WB0.819 (17)
C3—H3A0.9300O2W—H2WA0.833 (19)
C4—C51.400 (4)O2W—H2WB0.83 (4)
C4—C81.454 (3)
O1W—Zn1—O1112.85 (9)C5—C4—C8120.7 (2)
O1W—Zn1—O1i100.15 (8)C6—C5—C4118.7 (2)
O1—Zn1—O1i78.12 (7)C6—C5—H5A120.7
O1W—Zn1—Cl1113.49 (7)C4—C5—H5A120.7
O1—Zn1—Cl1130.77 (6)C5—C6—O2125.2 (2)
O1i—Zn1—Cl1108.86 (5)C5—C6—C1121.4 (2)
O1W—Zn1—O288.06 (8)O2—C6—C1113.4 (2)
O1—Zn1—O273.91 (6)O2—C7—H7A109.5
O1i—Zn1—O2151.87 (7)O2—C7—H7B109.5
Cl1—Zn1—O291.91 (6)H7A—C7—H7B109.5
O1W—Zn1—Zn1i111.21 (6)O2—C7—H7C109.5
O1—Zn1—Zn1i39.64 (5)H7A—C7—H7C109.5
O1i—Zn1—Zn1i38.48 (5)H7B—C7—H7C109.5
Cl1—Zn1—Zn1i128.75 (3)O3—C8—C4124.9 (3)
O2—Zn1—Zn1i113.49 (5)O3—C8—H8A117.6
O1—C1—C2123.4 (2)C4—C8—H8A117.6
O1—C1—C6117.7 (2)C1—O1—Zn1122.51 (15)
C2—C1—C6118.9 (2)C1—O1—Zn1i135.20 (15)
C1—C2—C3119.9 (2)Zn1—O1—Zn1i101.88 (7)
C1—C2—H2A120.1Zn1—O1W—H1WA126 (2)
C3—C2—H2A120.1Zn1—O1W—H1WB122 (2)
C4—C3—C2120.6 (2)H1WA—O1W—H1WB105 (2)
C4—C3—H3A119.7C6—O2—C7118.4 (2)
C2—C3—H3A119.7C6—O2—Zn1112.32 (14)
C3—C4—C5120.4 (2)C7—O2—Zn1128.87 (16)
C3—C4—C8118.8 (2)H2WA—O2W—H2WB103 (3)
O1—C1—C2—C3−177.0 (2)Cl1—Zn1—O1—C1−81.56 (19)
C6—C1—C2—C32.2 (4)O2—Zn1—O1—C1−3.26 (18)
C1—C2—C3—C40.4 (4)Zn1i—Zn1—O1—C1173.7 (2)
C2—C3—C4—C5−1.9 (4)O1W—Zn1—O1—Zn1i−96.13 (9)
C2—C3—C4—C8174.7 (2)O1i—Zn1—O1—Zn1i0.0
C3—C4—C5—C60.6 (4)Cl1—Zn1—O1—Zn1i104.76 (8)
C8—C4—C5—C6−175.9 (2)O2—Zn1—O1—Zn1i−176.94 (10)
C4—C5—C6—O2−178.3 (2)C5—C6—O2—C7−5.1 (4)
C4—C5—C6—C12.1 (4)C1—C6—O2—C7174.5 (2)
O1—C1—C6—C5175.7 (2)C5—C6—O2—Zn1−178.4 (2)
C2—C1—C6—C5−3.6 (4)C1—C6—O2—Zn11.2 (3)
O1—C1—C6—O2−3.9 (3)O1W—Zn1—O2—C6−113.56 (18)
C2—C1—C6—O2176.8 (2)O1—Zn1—O2—C60.91 (16)
C3—C4—C8—O3−173.8 (3)O1i—Zn1—O2—C6−5.5 (3)
C5—C4—C8—O32.8 (4)Cl1—Zn1—O2—C6133.00 (17)
C2—C1—O1—Zn1−175.52 (19)Zn1i—Zn1—O2—C6−1.22 (18)
C6—C1—O1—Zn15.2 (3)O1W—Zn1—O2—C774.0 (2)
C2—C1—O1—Zn1i−4.3 (4)O1—Zn1—O2—C7−171.5 (3)
C6—C1—O1—Zn1i176.41 (17)O1i—Zn1—O2—C7−177.9 (2)
O1W—Zn1—O1—C177.54 (19)Cl1—Zn1—O2—C7−39.4 (2)
O1i—Zn1—O1—C1173.7 (2)Zn1i—Zn1—O2—C7−173.6 (2)
Symmetry codes: (i) −x, −y+1, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WA···O3ii0.827 (17)1.847 (18)2.666 (3)171 (4)
O1W—H1WB···O2Wiii0.819 (17)1.854 (18)2.671 (3)175 (3)
O2W—H2WA···Cl10.833 (19)2.40 (3)3.190 (3)158 (6)
O2W—H2WB···Cl1iv0.83 (4)2.43 (4)3.258 (3)178 (6)
Symmetry codes: (ii) x−1, y, z−1; (iii) x−1, y, z; (iv) x+1/2, −y+1/2, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WA···O3i0.827 (17)1.847 (18)2.666 (3)171 (4)
O1W—H1WB···O2Wii0.819 (17)1.854 (18)2.671 (3)175 (3)
O2W—H2WA···Cl10.833 (19)2.40 (3)3.190 (3)158 (6)
O2W—H2WB···Cl1iii0.83 (4)2.43 (4)3.258 (3)178 (6)
Symmetry codes: (i) x−1, y, z−1; (ii) x−1, y, z; (iii) x+1/2, −y+1/2, z+1/2.
references
References top

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Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.

Tumer, M. T., Celik, C., Koksal, H. & Serin, S. (1999). Transition Met. Chem. 24, 525–532.