Aqua­{4,4′-dimeth­oxy-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­idyne)]diphenolato-κ⁴O,O′,N,N′}zinc(II)

In the title compound, [Zn(C₂₂H₁₈N₂O₄)(H₂O)], the Zn^II center, on a crystallographic mirror plane, is in a five-coordinate N₂O₃ environment that is approximately square pyramidal, with the N₂O₂ tetra­dentate Schiff base ligand as the basal plane and the water mol­ecule in the apical position. Inter­molecular O—H...O and weak C—H...O inter­actions link the mol­ecules into chains along [010]. These chains are further inter­connected in a zigzag manner into a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.027
• wR factor = 0.082
• Data-to-parameter ratio = 23.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.62 Ratio
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          1

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           32.50
           From the CIF: _reflns_number_total               3359
           Count of symmetry unique reflns         1786
           Completeness (_total/calc)            188.07%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1573
           Fraction of Friedel pairs measured     0.881
           Are heavy atom types Z>Si present        yes
PLAT794_ALERT_5_G Check Predicted Bond Valency for Zn1         (2)       2.08
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

It is well known that zinc complexes with Schiff-bases are active in biological systems and show very good activity against the leukemic cell (Tarafder et al., 2002). Recently, we reported the crystal structure of {2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato- κ⁴O,N,N',O'}(pyridine-κN)zinc(II) (Eltayeb et al., 2007). Herein, we report the crystal structure of (I).

In (I), the Zn1 and O1W atoms lie on a mirror plane and the asymmetric unit therefore contains only half of the molecule. The tetradentate Schiff-base ligand is almost planar with a maximum deviation from the C1–C10/O1–O2/N1 plane of 0.053 (3) Å for atom N1. The methoxy group is slightly twisted from the C1–C10/O1–O2/N1 mean plane as indicated by the torsion angle C11/O2/C4/C5 of -9.6 (2)°. The ligand is coordinated to Zn1 as a tetradentate ligand via through two N and two O donor atoms, resulting in a square-pyramidal Zn^II center whose fifth (axial) position is occupied by a water molecule (Fig. 1). The four atoms N1, O1, N1ⁱ and O1ⁱ [i = -x, y, z] form the basal plane, and the Zn^II is displaced 0.044 (7) Å out of this mean basal plane towards the axial water molecule. Bond lengths and angles observed in the structure are normal (Allen et al., 1987).

In the crystal of (I) in Fig. 2, the water molecule is involved in an intermolecular O—H···O hydrogen bond [O1W—H1W···O1; symmetry code x, -1 + y, +z] and the ligand is involved in weak C—H···O intermolecular interaction [C7—H7A···O2; symmetry code 1/2 - x, -y, -1/2 + z] (Table 2). The molcecules are linked into chains along the b axis. These chains are further interconnected in a zig-zag manner into a three-dimensional network.

Related literature

For related literature on values of bond lengths and angles, see: Allen et al. (1987). For related structures, see, for example: Humphrey et al. (1999); Eltayeb, Teoh, Ng et al. (2007); Eltayeb, Teoh, Fun et al. (2007). For related literature, see: Tarafder et al. (2002).

S2. Experimental

The title compound (I) was synthesized by adding 5-methoxy-2-hydroxybenzaldehyde (0.610 g, 4 mmol) to a solution of o-phenylenediamine (0.216 g, 2 mmol) in ethanol 95% (20 ml). The mixture was refluxed with stirring for half an hour. Zinc chloride (0.272 g, 2 mmol) in ethanol (10 ml) was then added, followed by triethylamine (0.5 ml,3.6 mmol). The mixture was stirred at room temperature for two h. An orange-red precipitate was obtained; this was washed by about 5 ml e thanol, dried, and then washed by copious amount of diethyl ether. This precipitate was then dissolved in 25 ml of pyridine. Red single crystals were formed after two months.

S3. Refinement

The water hydrogen atoms were located in a difference map and were restrained with an O1W—H distance of 0.82 Å. All other H atoms were positioned geometrically and allowed to ride on their parent atoms with C—H distances in the range 0.93–0.96 Å. The U_iso values were constrained to be 1.5U_eq of the carrier atom for methyl H atoms and 1.2U_eq for the remaining H atoms. A rotating group model was used for the methyl groups; 1573 Friedel pairs were used to determine the absolute structure.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures

	Fig. 1. The asymmetric unit of (I), showing 50% probability displacement ellipsoids and the atomic numbering.
	Fig. 2. The crystal packing of (I), viewed along the b axis. Hydrogen bonds are shown as dash lines.

Aqua{4,4'-dimethoxy-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato- κ⁴O,O',N,N'}zinc(II)

Crystal data

[Zn(C22H18N2O4)(H2O)]	F(000) = 472
Mr = 457.79	Dx = 1.668 Mg m^−3
Orthorhombic, Pmn21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac -2	Cell parameters from 3359 reflections
a = 23.3617 (7) Å	θ = 1.7–32.5°
b = 4.9121 (1) Å	µ = 1.39 mm^−1
c = 7.9431 (2) Å	T = 100 K
V = 911.51 (4) Å^3	Plate, red
Z = 2	0.38 × 0.23 × 0.10 mm

Data collection

Bruker SMART APEX2 CCD area-detector diffractometer	3359 independent reflections
Radiation source: fine-focus sealed tube	3179 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 8.33 pixels mm^-1	θmax = 32.5°, θmin = 1.7°
ω scans	h = −35→35
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −7→7
Tmin = 0.623, Tmax = 0.874	l = −12→12
29716 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.027	H-atom parameters constrained
wR(F^2) = 0.082	w = 1/[σ^2(Fo^2) + (0.0476P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
3359 reflections	Δρmax = 0.49 e Å^−3
141 parameters	Δρmin = −0.70 e Å^−3
2 restraints	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.012 (10)

Special details

Experimental. The low-temparture data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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 (Ų)

	x	y	z	Uiso*/Ueq
Zn1	0.0000	0.05705 (5)	0.10449 (4)	0.01253 (7)
O1	0.06065 (5)	0.3095 (3)	0.17986 (17)	0.0153 (2)
O2	0.29634 (5)	0.2460 (3)	0.13415 (15)	0.0170 (3)
O1W	0.0000	−0.2503 (4)	0.2826 (2)	0.0169 (3)
H1W1	0.0270	−0.3532	0.2651	0.058 (11)*
C1	0.11623 (7)	0.2828 (4)	0.1586 (2)	0.0133 (3)
C2	0.15306 (8)	0.4597 (3)	0.2488 (2)	0.0146 (3)
H2A	0.1369	0.5913	0.3184	0.017*
C3	0.21158 (8)	0.4445 (3)	0.2376 (2)	0.0148 (3)
H3A	0.2343	0.5649	0.2985	0.018*
C4	0.23727 (7)	0.2473 (4)	0.1342 (2)	0.0143 (3)
C5	0.20328 (7)	0.0725 (3)	0.0424 (2)	0.0133 (3)
H5A	0.2203	−0.0567	−0.0270	0.016*
C6	0.14266 (7)	0.0866 (3)	0.0522 (2)	0.0128 (3)
C7	0.11221 (7)	−0.1066 (4)	−0.0513 (2)	0.0136 (3)
H7A	0.1340	−0.2240	−0.1170	0.016*
C8	0.03036 (6)	−0.3179 (3)	−0.1707 (2)	0.0127 (3)
C9	0.05973 (7)	−0.4942 (4)	−0.2795 (2)	0.0152 (3)
H9A	0.0995	−0.4962	−0.2795	0.018*
N1	0.05703 (6)	−0.1304 (3)	−0.06032 (18)	0.0128 (3)
C10	0.02998 (6)	−0.6654 (3)	−0.3870 (3)	0.0156 (3)
H10A	0.0499	−0.7806	−0.4593	0.019*
C11	0.32314 (8)	0.0220 (4)	0.0525 (3)	0.0185 (3)
H11A	0.3638	0.0333	0.0678	0.028*
H11B	0.3144	0.0266	−0.0655	0.028*
H11C	0.3093	−0.1451	0.1002	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.01071 (11)	0.01086 (11)	0.01601 (12)	0.000	0.000	−0.00136 (12)
O1	0.0101 (5)	0.0129 (5)	0.0231 (6)	−0.0003 (4)	−0.0004 (4)	−0.0032 (5)
O2	0.0102 (5)	0.0185 (6)	0.0223 (8)	−0.0005 (4)	−0.0013 (4)	−0.0038 (5)
O1W	0.0191 (8)	0.0129 (8)	0.0188 (8)	0.000	0.000	0.0001 (7)
C1	0.0123 (7)	0.0122 (7)	0.0154 (7)	0.0004 (5)	−0.0006 (5)	0.0012 (5)
C2	0.0133 (7)	0.0113 (7)	0.0191 (8)	0.0007 (5)	−0.0001 (6)	−0.0014 (6)
C3	0.0134 (7)	0.0130 (8)	0.0179 (8)	−0.0021 (5)	−0.0013 (6)	−0.0006 (6)
C4	0.0116 (6)	0.0137 (7)	0.0176 (10)	0.0004 (5)	−0.0010 (5)	0.0009 (5)
C5	0.0102 (6)	0.0136 (7)	0.0161 (7)	0.0003 (5)	0.0010 (5)	−0.0003 (6)
C6	0.0110 (7)	0.0129 (7)	0.0144 (6)	−0.0008 (5)	−0.0011 (5)	0.0005 (5)
C7	0.0122 (7)	0.0147 (7)	0.0140 (7)	−0.0005 (5)	0.0010 (6)	−0.0007 (5)
C8	0.0122 (7)	0.0118 (7)	0.0141 (7)	−0.0010 (5)	−0.0001 (5)	0.0001 (6)
C9	0.0118 (7)	0.0176 (7)	0.0161 (8)	0.0010 (6)	0.0004 (6)	−0.0017 (6)
N1	0.0122 (6)	0.0116 (6)	0.0147 (6)	−0.0009 (5)	−0.0006 (5)	−0.0014 (5)
C10	0.0148 (6)	0.0149 (6)	0.0170 (7)	0.0013 (5)	0.0014 (8)	−0.0040 (8)
C11	0.0133 (7)	0.0178 (8)	0.0244 (9)	0.0005 (6)	0.0002 (6)	−0.0018 (6)

Geometric parameters (Å, º)

Zn1—O1	1.9758 (12)	C5—C6	1.420 (2)
Zn1—O1^i	1.9758 (12)	C5—H5A	0.9300
Zn1—O1W	2.069 (2)	C6—C7	1.443 (2)
Zn1—N1	2.0825 (14)	C7—N1	1.296 (2)
Zn1—N1^i	2.0826 (14)	C7—H7A	0.9300
O1—C1	1.316 (2)	C8—C9	1.403 (2)
O2—C4	1.3800 (19)	C8—N1	1.416 (2)
O2—C11	1.422 (2)	C8—C8^i	1.419 (3)
O1W—H1W1	0.8200	C9—C10	1.385 (3)
C1—C2	1.417 (2)	C9—H9A	0.9300
C1—C6	1.423 (2)	C10—C10^i	1.401 (3)
C2—C3	1.372 (2)	C10—H10A	0.9300
C2—H2A	0.9300	C11—H11A	0.9600
C3—C4	1.404 (2)	C11—H11B	0.9600
C3—H3A	0.9300	C11—H11C	0.9600
C4—C5	1.379 (2)
O1—Zn1—O1^i	91.64 (7)	C4—C5—H5A	119.5
O1—Zn1—O1W	104.52 (6)	C6—C5—H5A	119.5
O1^i—Zn1—O1W	104.52 (6)	C5—C6—C1	119.90 (15)
O1—Zn1—N1	90.52 (6)	C5—C6—C7	115.35 (15)
O1^i—Zn1—N1	157.94 (6)	C1—C6—C7	124.75 (16)
O1W—Zn1—N1	96.16 (6)	N1—C7—C6	125.52 (16)
O1—Zn1—N1^i	157.94 (6)	N1—C7—H7A	117.2
O1^i—Zn1—N1^i	90.52 (6)	C6—C7—H7A	117.2
O1W—Zn1—N1^i	96.16 (6)	C9—C8—N1	124.60 (14)
N1—Zn1—N1^i	79.56 (8)	C9—C8—C8^i	119.28 (10)
C1—O1—Zn1	127.32 (11)	N1—C8—C8^i	116.10 (8)
C4—O2—C11	116.36 (14)	C10—C9—C8	120.61 (15)
Zn1—O1W—H1W1	109.5	C10—C9—H9A	119.7
O1—C1—C2	118.24 (16)	C8—C9—H9A	119.7
O1—C1—C6	124.88 (16)	C7—N1—C8	122.04 (15)
C2—C1—C6	116.87 (15)	C7—N1—Zn1	124.16 (12)
C3—C2—C1	122.59 (16)	C8—N1—Zn1	113.29 (10)
C3—C2—H2A	118.7	C9—C10—C10^i	120.11 (10)
C1—C2—H2A	118.7	C9—C10—H10A	119.9
C2—C3—C4	120.10 (16)	C10^i—C10—H10A	119.9
C2—C3—H3A	119.9	O2—C11—H11A	109.5
C4—C3—H3A	119.9	O2—C11—H11B	109.5
C5—C4—O2	124.95 (15)	H11A—C11—H11B	109.5
C5—C4—C3	119.53 (15)	O2—C11—H11C	109.5
O2—C4—C3	115.52 (15)	H11A—C11—H11C	109.5
C4—C5—C6	120.99 (16)	H11B—C11—H11C	109.5
O1^i—Zn1—O1—C1	−174.80 (12)	C2—C1—C6—C7	−178.82 (16)
O1W—Zn1—O1—C1	79.74 (15)	C5—C6—C7—N1	179.40 (17)
N1—Zn1—O1—C1	−16.75 (15)	C1—C6—C7—N1	−0.8 (3)
N1^i—Zn1—O1—C1	−79.4 (2)	N1—C8—C9—C10	−178.03 (17)
Zn1—O1—C1—C2	−168.48 (12)	C8^i—C8—C9—C10	0.5 (2)
Zn1—O1—C1—C6	10.9 (3)	C6—C7—N1—C8	177.22 (16)
O1—C1—C2—C3	178.75 (17)	C6—C7—N1—Zn1	−11.6 (3)
C6—C1—C2—C3	−0.7 (3)	C9—C8—N1—C7	0.1 (3)
C1—C2—C3—C4	−0.3 (3)	C8^i—C8—N1—C7	−178.52 (13)
C11—O2—C4—C5	−9.7 (2)	C9—C8—N1—Zn1	−172.00 (14)
C11—O2—C4—C3	170.21 (16)	C8^i—C8—N1—Zn1	9.43 (12)
C2—C3—C4—C5	1.0 (3)	O1—Zn1—N1—C7	16.93 (15)
C2—C3—C4—O2	−178.87 (16)	O1^i—Zn1—N1—C7	112.60 (18)
O2—C4—C5—C6	179.13 (15)	O1W—Zn1—N1—C7	−87.74 (15)
C3—C4—C5—C6	−0.7 (3)	N1^i—Zn1—N1—C7	177.11 (12)
C4—C5—C6—C1	−0.3 (3)	O1—Zn1—N1—C8	−171.21 (12)
C4—C5—C6—C7	179.54 (16)	O1^i—Zn1—N1—C8	−75.55 (19)
O1—C1—C6—C5	−178.45 (16)	O1W—Zn1—N1—C8	84.12 (11)
C2—C1—C6—C5	1.0 (2)	N1^i—Zn1—N1—C8	−11.03 (14)
O1—C1—C6—C7	1.8 (3)	C8—C9—C10—C10^i	−0.5 (2)

Symmetry code: (i) −x, y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O1^ii	0.82	1.96	2.711 (2)	153
C7—H7A···O2^iii	0.94	2.56	3.358 (2)	144

Symmetry codes: (ii) x, y−1, z; (iii) −x+1/2, −y, z−1/2.