Aqua­bis(5-methyl­pyrazine-2-carboxyl­ato)zinc(II) trihydrate

Cui, Y.-M.; Li, J.; Zhang, X.; Zeng, Q.-F.

doi:10.1107/S1600536809031778

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 9| September 2009| Pages m1083-m1084

doi:10.1107/S1600536809031778

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Aquabis(5-methylpyrazine-2-carboxylato)zinc(II) trihydrate

Yong-Ming Cui,^a Jin Li,^a Xian Zhang ^a and Qing-Fu Zeng ^a ^*

^aEngineering Research Center for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan 430073, People's Republic of China
^*Correspondence e-mail: qfzeng@wuse.edu.cn

(Received 9 August 2009; accepted 12 August 2009; online 19 August 2009)

In the title compound, [Zn(C₆H₅N₂O₂)₂(H₂O)]·3H₂O, the Zn^II centre is five-coordinated by two O,N-bidentate Schiff base ligands and one O atom from a water molecule in a slightly distorted square-pyramidal geometry. In the crystal, the complex and uncoordinated water molecules are linked by O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, forming a three-dimensional network.

Related literature

For background to the molecular architecture and biological activity of benzoic acid–metal complexes, see: Cheng et al. (2006 ); Yang et al. (2004 ). For reference structural data, see: Allen et al. (1987 ).

Experimental

Crystal data

[Zn(C₆H₅N₂O₂)₂(H₂O)]·3H₂O
M_r = 411.67
Triclinic, $[P \overline 1]$
a = 8.134 (4) Å
b = 10.492 (5) Å
c = 10.982 (5) Å
α = 66.61 (2)°
β = 81.85 (2)°
γ = 78.33 (2)°
V = 840.3 (7) Å³
Z = 2
Mo Kα radiation
μ = 1.51 mm⁻¹
T = 296 K
0.32 × 0.28 × 0.23 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.644, T_max = 0.723
4392 measured reflections
2923 independent reflections
2539 reflections with I > 2σ(I)
R_int = 0.018
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.109
S = 1.05
2923 reflections
260 parameters
12 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.68 e Å⁻³

Table 1
Selected bond lengths (Å)

Zn1—N1	1.989 (2)
Zn1—N3	1.985 (2)
Zn1—O2	1.951 (2)
Zn1—O4	1.957 (2)
Zn1—O5	2.245 (3)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C9—H9⋯O1ⁱ	0.93	2.35	3.204 (4)	153
C3—H3⋯O3ⁱⁱ	0.93	2.36	3.255 (4)	162
O8—H8B⋯N4ⁱⁱ	0.832 (10)	2.30 (2)	3.044 (4)	150 (3)
O6—H6E⋯O7	0.841 (10)	2.092 (11)	2.932 (4)	177 (4)
O6—H6D⋯O8	0.839 (10)	1.924 (14)	2.755 (4)	171 (4)
O8—H8A⋯O1	0.835 (10)	1.953 (13)	2.781 (4)	171 (4)
O7—H7B⋯O3ⁱⁱⁱ	0.836 (10)	1.996 (18)	2.797 (3)	160 (4)
O7—H7A⋯N2^iv	0.839 (10)	2.185 (18)	2.977 (4)	157 (3)
O5—H5B⋯O6^v	0.835 (10)	1.924 (11)	2.754 (4)	172 (3)
O5—H5A⋯O7^vi	0.830 (10)	2.034 (11)	2.861 (4)	175 (4)
Symmetry codes: (i) x, y-1, z; (ii) x, y+1, z; (iii) -x+1, -y+1, -z+1; (iv) -x+1, -y+2, -z+1; (v) -x+1, -y+1, -z+2; (vi) x+1, y, z.

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ); cell refinement: CAD-4 Software; 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: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809031778/hb5038sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809031778/hb5038Isup2.hkl

checkCIF report

Comment top

There has been much research interest in benzoic acid metal complexes due to their molecular architectures and biological activities (Cheng et al., 2006; Yang et al., 2004). In this work, we report here the crystal structure of the title compound, (I). In (I), all bond lengths are within normal ranges (Allen et al., 1987) (Fig. 1). The Zn^II atom is five-coordinated by two O and two N atoms from the two Schiff base ligands and one O from the water molecule, forming a slightly distorted square pyramid coordination (Table 1). The mononuclear complex interacts with the solvent water molecules to form a three-dimensional network (Table 2).

Related literature top

For background to the molecular architecture and biological activity of benzoic acid–metal complexes, see: Cheng et al. (2006); Yang et al. (2004). For reference structural data, see: Allen et al. (1987);

Experimental top

A mixture of 5-methylpyrazine-2-carboxylic acid (276 mg, 2 mmol) and Zn(NO₃)₂.6H₂O (1 mmol, 271 mg) in methanol (10 ml) was stirred for 3 h. After keeping the filtrate in air for 7 d, colourless blocks of (I) were formed.

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); 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: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of (I) showing 30% probability displacement ellipsoids.

Aquabis(5-methylpyrazine-2-carboxylato)zinc(II) trihydrate top

Crystal data top

[Zn(C₆H₅N₂O₂)₂(H₂O)]·3H₂O	Z = 2
M_r = 411.67	F(000) = 424
Triclinic, P1	D_x = 1.627 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.134 (4) Å	Cell parameters from 25 reflections
b = 10.492 (5) Å	θ = 9–12°
c = 10.982 (5) Å	µ = 1.51 mm⁻¹
α = 66.61 (2)°	T = 296 K
β = 81.85 (2)°	Block, colourless
γ = 78.33 (2)°	0.32 × 0.28 × 0.23 mm
V = 840.3 (7) Å³

Data collection top

Enraf–Nonius CAD-4 diffractometer	2539 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.018
Graphite monochromator	θ_max = 25.0°, θ_min = 2.0°
ω/2θ scans	h = −9→9
Absorption correction: ψ scan (North et al., 1968)	k = −12→12
T_min = 0.644, T_max = 0.723	l = −13→13
4392 measured reflections	3 standard reflections every 200 reflections
2923 independent reflections	intensity decay: 1%

Refinement top

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0629P)² + 0.6023P] where P = (F_o² + 2F_c²)/3
2923 reflections	(Δ/σ)_max = 0.016
260 parameters	Δρ_max = 0.43 e Å⁻³
12 restraints	Δρ_min = −0.68 e Å⁻³

Crystal data top

[Zn(C₆H₅N₂O₂)₂(H₂O)]·3H₂O	γ = 78.33 (2)°
M_r = 411.67	V = 840.3 (7) Å³
Triclinic, P1	Z = 2
a = 8.134 (4) Å	Mo Kα radiation
b = 10.492 (5) Å	µ = 1.51 mm⁻¹
c = 10.982 (5) Å	T = 296 K
α = 66.61 (2)°	0.32 × 0.28 × 0.23 mm
β = 81.85 (2)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	2539 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.018
T_min = 0.644, T_max = 0.723	3 standard reflections every 200 reflections
4392 measured reflections	intensity decay: 1%
2923 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	12 restraints
wR(F²) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.43 e Å⁻³
2923 reflections	Δρ_min = −0.68 e Å⁻³
260 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 > 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

	x	y	z	U_iso*/U_eq
C1	0.6126 (4)	0.8388 (3)	0.6598 (3)	0.0398 (8)
C2	0.7345 (4)	0.8625 (3)	0.5379 (3)	0.0328 (7)
C3	0.7920 (4)	0.9875 (3)	0.4653 (3)	0.0402 (8)
H3	0.7551	1.0635	0.4912	0.048*
C4	0.9502 (4)	0.8932 (3)	0.3229 (3)	0.0371 (7)
C5	0.8939 (4)	0.7652 (3)	0.3960 (3)	0.0358 (7)
H5	0.9310	0.6891	0.3703	0.043*
C6	1.0683 (5)	0.9107 (4)	0.2018 (4)	0.0555 (10)
H6A	1.0163	0.9832	0.1257	0.083*
H6B	1.0947	0.8237	0.1881	0.083*
H6C	1.1699	0.9363	0.2139	0.083*
C7	0.6723 (4)	0.3717 (3)	0.5483 (3)	0.0350 (7)
C8	0.5573 (4)	0.3445 (3)	0.6745 (3)	0.0315 (7)
C9	0.4702 (4)	0.2334 (3)	0.7297 (3)	0.0387 (7)
H9	0.4846	0.1673	0.6908	0.046*
C10	0.3477 (4)	0.3130 (4)	0.8926 (3)	0.0381 (7)
C11	0.4392 (4)	0.4242 (3)	0.8389 (3)	0.0362 (7)
H11	0.4281	0.4886	0.8793	0.043*
C12	0.2293 (5)	0.2978 (4)	1.0126 (4)	0.0533 (10)
H12A	0.1158	0.3146	0.9883	0.080*
H12B	0.2421	0.3647	1.0487	0.080*
H12C	0.2539	0.2042	1.0781	0.080*
H5A	0.964 (4)	0.540 (3)	0.750 (3)	0.040 (10)*
H7A	0.070 (5)	0.7757 (14)	0.720 (4)	0.056 (12)*
H8A	0.406 (6)	0.908 (4)	0.855 (3)	0.090 (18)*
H5B	0.875 (4)	0.438 (3)	0.8366 (14)	0.048 (11)*
H7B	0.175 (4)	0.675 (4)	0.683 (3)	0.076 (15)*
H8B	0.329 (5)	0.985 (2)	0.929 (3)	0.049 (12)*
H6D	0.259 (6)	0.734 (3)	0.977 (4)	0.088 (18)*
H6E	0.183 (5)	0.674 (4)	0.915 (2)	0.065 (14)*
N1	0.7865 (3)	0.7518 (3)	0.5033 (2)	0.0317 (6)
N2	0.9005 (4)	1.0029 (3)	0.3579 (3)	0.0417 (7)
N3	0.5426 (3)	0.4391 (3)	0.7298 (2)	0.0318 (6)
N4	0.3644 (4)	0.2175 (3)	0.8390 (3)	0.0405 (7)
O1	0.5584 (4)	0.9371 (3)	0.6954 (3)	0.0624 (8)
O2	0.5775 (3)	0.7154 (2)	0.7156 (2)	0.0423 (6)
O3	0.6850 (4)	0.2940 (2)	0.4880 (2)	0.0514 (7)
O4	0.7438 (3)	0.4786 (2)	0.5142 (2)	0.0394 (5)
O5	0.9020 (3)	0.4833 (3)	0.7568 (2)	0.0449 (6)
O6	0.2178 (4)	0.6625 (3)	0.9876 (3)	0.0635 (8)
O7	0.0982 (4)	0.6891 (3)	0.7377 (3)	0.0494 (6)
O8	0.3459 (4)	0.9068 (3)	0.9238 (3)	0.0654 (8)
Zn1	0.68363 (5)	0.58672 (4)	0.62838 (4)	0.03747 (16)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0472 (19)	0.0338 (17)	0.0442 (18)	−0.0088 (14)	0.0072 (15)	−0.0233 (15)
C2	0.0402 (17)	0.0294 (15)	0.0330 (15)	−0.0068 (13)	−0.0022 (13)	−0.0157 (13)
C3	0.051 (2)	0.0308 (16)	0.0444 (18)	−0.0087 (14)	0.0016 (15)	−0.0211 (15)
C4	0.0361 (17)	0.0369 (17)	0.0363 (16)	−0.0046 (13)	−0.0006 (13)	−0.0131 (14)
C5	0.0402 (18)	0.0325 (16)	0.0380 (17)	−0.0037 (13)	−0.0005 (14)	−0.0187 (14)
C6	0.059 (2)	0.048 (2)	0.050 (2)	−0.0061 (18)	0.0150 (18)	−0.0161 (18)
C7	0.0468 (18)	0.0249 (15)	0.0339 (16)	−0.0017 (13)	−0.0005 (14)	−0.0146 (13)
C8	0.0359 (16)	0.0247 (14)	0.0368 (16)	−0.0031 (12)	−0.0015 (13)	−0.0158 (13)
C9	0.0465 (19)	0.0318 (16)	0.0431 (18)	−0.0077 (14)	−0.0030 (15)	−0.0190 (15)
C10	0.0327 (17)	0.0417 (18)	0.0410 (17)	−0.0068 (13)	0.0010 (13)	−0.0178 (15)
C11	0.0392 (17)	0.0352 (16)	0.0406 (17)	−0.0054 (13)	0.0015 (14)	−0.0226 (14)
C12	0.053 (2)	0.062 (2)	0.050 (2)	−0.0182 (18)	0.0151 (17)	−0.0278 (19)
N1	0.0369 (14)	0.0270 (12)	0.0339 (13)	−0.0041 (10)	−0.0003 (11)	−0.0158 (11)
N2	0.0494 (17)	0.0327 (14)	0.0427 (15)	−0.0095 (12)	0.0032 (13)	−0.0147 (12)
N3	0.0352 (14)	0.0287 (13)	0.0349 (13)	−0.0047 (10)	0.0007 (11)	−0.0169 (11)
N4	0.0444 (16)	0.0356 (14)	0.0450 (16)	−0.0121 (12)	0.0025 (13)	−0.0181 (13)
O1	0.092 (2)	0.0378 (13)	0.0634 (17)	−0.0178 (13)	0.0312 (15)	−0.0344 (13)
O2	0.0563 (14)	0.0331 (12)	0.0444 (13)	−0.0164 (10)	0.0166 (11)	−0.0243 (10)
O3	0.0831 (19)	0.0376 (13)	0.0436 (13)	−0.0201 (12)	0.0148 (13)	−0.0273 (11)
O4	0.0550 (14)	0.0322 (12)	0.0372 (12)	−0.0144 (10)	0.0103 (10)	−0.0205 (10)
O5	0.0494 (15)	0.0442 (14)	0.0403 (14)	−0.0148 (11)	0.0000 (11)	−0.0127 (12)
O6	0.079 (2)	0.071 (2)	0.0412 (15)	−0.0360 (17)	0.0014 (14)	−0.0121 (14)
O7	0.0609 (17)	0.0442 (15)	0.0444 (14)	−0.0189 (12)	0.0128 (12)	−0.0185 (12)
O8	0.080 (2)	0.0525 (18)	0.0684 (19)	−0.0268 (15)	0.0282 (16)	−0.0311 (15)
Zn1	0.0488 (3)	0.0304 (2)	0.0392 (2)	−0.01200 (16)	0.00646 (16)	−0.01988 (17)

Geometric parameters (Å, º) top

C1—O1	1.224 (4)	C10—N4	1.327 (4)
C1—O2	1.266 (4)	C10—C11	1.394 (5)
C1—C2	1.516 (4)	C10—C12	1.492 (5)
C2—N1	1.334 (4)	C11—N3	1.336 (4)
C2—C3	1.373 (4)	C11—H11	0.9300
C3—N2	1.345 (4)	C12—H12A	0.9600
C3—H3	0.9300	C12—H12B	0.9600
C4—N2	1.325 (4)	C12—H12C	0.9600
C4—C5	1.395 (5)	Zn1—N1	1.989 (2)
C4—C6	1.497 (5)	Zn1—N3	1.985 (2)
C5—N1	1.341 (4)	Zn1—O2	1.951 (2)
C5—H5	0.9300	Zn1—O4	1.957 (2)
C6—H6A	0.9600	Zn1—O5	2.245 (3)
C6—H6B	0.9600	O5—H5A	0.830 (10)
C6—H6C	0.9600	O5—H5B	0.835 (10)
C7—O3	1.221 (4)	O6—H6D	0.839 (10)
C7—O4	1.267 (4)	O6—H6E	0.841 (10)
C7—C8	1.518 (4)	O7—H7A	0.839 (10)
C8—N3	1.334 (4)	O7—H7B	0.836 (10)
C8—C9	1.370 (4)	O8—H8A	0.835 (10)
C9—N4	1.347 (4)	O8—H8B	0.832 (10)
C9—H9	0.9300

O1—C1—O2	126.4 (3)	N3—C11—H11	119.7
O1—C1—C2	118.7 (3)	C10—C11—H11	119.7
O2—C1—C2	115.0 (3)	C10—C12—H12A	109.5
N1—C2—C3	120.3 (3)	C10—C12—H12B	109.5
N1—C2—C1	115.6 (3)	H12A—C12—H12B	109.5
C3—C2—C1	124.1 (3)	C10—C12—H12C	109.5
N2—C3—C2	121.7 (3)	H12A—C12—H12C	109.5
N2—C3—H3	119.2	H12B—C12—H12C	109.5
C2—C3—H3	119.2	C2—N1—C5	118.9 (3)
N2—C4—C5	121.2 (3)	C2—N1—Zn1	110.7 (2)
N2—C4—C6	118.0 (3)	C5—N1—Zn1	130.3 (2)
C5—C4—C6	120.8 (3)	C4—N2—C3	117.8 (3)
N1—C5—C4	120.0 (3)	C8—N3—C11	118.4 (3)
N1—C5—H5	120.0	C8—N3—Zn1	111.5 (2)
C4—C5—H5	120.0	C11—N3—Zn1	130.1 (2)
C4—C6—H6A	109.5	C10—N4—C9	117.6 (3)
C4—C6—H6B	109.5	C1—O2—Zn1	115.0 (2)
H6A—C6—H6B	109.5	C7—O4—Zn1	115.3 (2)
C4—C6—H6C	109.5	Zn1—O5—H5A	112 (2)
H6A—C6—H6C	109.5	Zn1—O5—H5B	114 (2)
H6B—C6—H6C	109.5	H5A—O5—H5B	110.6 (17)
O3—C7—O4	126.2 (3)	H6D—O6—H6E	108.5 (17)
O3—C7—C8	119.0 (3)	H7A—O7—H7B	109.8 (17)
O4—C7—C8	114.8 (3)	H8A—O8—H8B	110.3 (18)
N3—C8—C9	120.6 (3)	O2—Zn1—O4	166.16 (10)
N3—C8—C7	115.2 (3)	O2—Zn1—N3	95.36 (10)
C9—C8—C7	124.2 (3)	O4—Zn1—N3	83.22 (9)
N4—C9—C8	121.7 (3)	O2—Zn1—N1	83.64 (9)
N4—C9—H9	119.2	O4—Zn1—N1	95.00 (10)
C8—C9—H9	119.2	N3—Zn1—N1	168.45 (10)
N4—C10—C11	121.0 (3)	O2—Zn1—O5	97.35 (10)
N4—C10—C12	118.2 (3)	O4—Zn1—O5	96.49 (10)
C11—C10—C12	120.8 (3)	N3—Zn1—O5	94.98 (10)
N3—C11—C10	120.6 (3)	N1—Zn1—O5	96.55 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9···O1ⁱ	0.93	2.35	3.204 (4)	153
C3—H3···O3ⁱⁱ	0.93	2.36	3.255 (4)	162
O8—H8B···N4ⁱⁱ	0.83 (1)	2.30 (2)	3.044 (4)	150 (3)
O6—H6E···O7	0.84 (1)	2.09 (1)	2.932 (4)	177 (4)
O6—H6D···O8	0.84 (1)	1.92 (1)	2.755 (4)	171 (4)
O8—H8A···O1	0.84 (1)	1.95 (1)	2.781 (4)	171 (4)
O7—H7B···O3ⁱⁱⁱ	0.84 (1)	2.00 (2)	2.797 (3)	160 (4)
O7—H7A···N2^iv	0.84 (1)	2.19 (2)	2.977 (4)	157 (3)
O5—H5B···O6^v	0.84 (1)	1.92 (1)	2.754 (4)	172 (3)
O5—H5A···O7^vi	0.83 (1)	2.03 (1)	2.861 (4)	175 (4)

Symmetry codes: (i) x, y−1, z; (ii) x, y+1, z; (iii) −x+1, −y+1, −z+1; (iv) −x+1, −y+2, −z+1; (v) −x+1, −y+1, −z+2; (vi) x+1, y, z.

Experimental details

Crystal data
Chemical formula	[Zn(C₆H₅N₂O₂)₂(H₂O)]·3H₂O
M_r	411.67
Crystal system, space group	Triclinic, P1
Temperature (K)	296
a, b, c (Å)	8.134 (4), 10.492 (5), 10.982 (5)
α, β, γ (°)	66.61 (2), 81.85 (2), 78.33 (2)
V (Å³)	840.3 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	1.51
Crystal size (mm)	0.32 × 0.28 × 0.23

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.644, 0.723
No. of measured, independent and observed [I > 2σ(I)] reflections	4392, 2923, 2539
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.109, 1.05
No. of reflections	2923
No. of parameters	260
No. of restraints	12
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.68

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Zn1—N1	1.989 (2)	Zn1—O4	1.957 (2)
Zn1—N3	1.985 (2)	Zn1—O5	2.245 (3)
Zn1—O2	1.951 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9···O1ⁱ	0.93	2.35	3.204 (4)	153
C3—H3···O3ⁱⁱ	0.93	2.36	3.255 (4)	162
O8—H8B···N4ⁱⁱ	0.832 (10)	2.30 (2)	3.044 (4)	150 (3)
O6—H6E···O7	0.841 (10)	2.092 (11)	2.932 (4)	177 (4)
O6—H6D···O8	0.839 (10)	1.924 (14)	2.755 (4)	171 (4)
O8—H8A···O1	0.835 (10)	1.953 (13)	2.781 (4)	171 (4)
O7—H7B···O3ⁱⁱⁱ	0.836 (10)	1.996 (18)	2.797 (3)	160 (4)
O7—H7A···N2^iv	0.839 (10)	2.185 (18)	2.977 (4)	157 (3)
O5—H5B···O6^v	0.835 (10)	1.924 (11)	2.754 (4)	172 (3)
O5—H5A···O7^vi	0.830 (10)	2.034 (11)	2.861 (4)	175 (4)

Symmetry codes: (i) x, y−1, z; (ii) x, y+1, z; (iii) −x+1, −y+1, −z+1; (iv) −x+1, −y+2, −z+1; (v) −x+1, −y+1, −z+2; (vi) x+1, y, z.

Acknowledgements

The project was supported by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry, Educational Commission of Hubei Province (D20091703) and the Natural Science Foundation of Hubei Province (2008CDB038).

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19. CrossRef Web of Science Google Scholar
Cheng, K., Zhu, H.-L. & Li, Y.-G. (2006). Z. Anorg. Allg. Chem. 632, 2326–2330. Web of Science CSD CrossRef Google Scholar
Enraf–Nonius (1989). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Google Scholar
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359. CrossRef IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yang, H.-L., You, Z.-L. & Zhu, H.-L. (2004). Acta Cryst. E60, m1213–m1214. Web of Science CSD CrossRef IUCr Journals Google Scholar