Aqua­bis­(4-chloro-2-hy­droxy­benzoato-κO)(1,10-phenanthroline-κ2 N,N′)zinc(II)

Jing-Jing Nie; Xun Xu; Duan-Jun Xu

doi:10.1107/S1600536811020435

. 2011 Jun 4;67(Pt 7):m855–m856. doi: 10.1107/S1600536811020435

Aquabis(4-chloro-2-hydroxybenzoato-κO)(1,10-phenanthroline-κ² N,N′)zinc(II)

Jing-Jing Nie ^a, Xun Xu ^b, Duan-Jun Xu ^a,^*

PMCID: PMC3151932 PMID: 21836855

Abstract

In the title compound, [Zn(C₇H₄ClO₃)₂(C₁₂H₈N₂)(H₂O)], the Zn^II cation is coordinated by two 4-chloro-2-salicylate anions, one 1,10-phenanthroline ligand and one water molecule in a square-pyramidal coordination geometry; the Zn cation lies 0.4591 (11) Å from the basal plane. The benzene rings of the anions are involved in π–π stacking. The centroid–centroid distance between parallel benzene rings of adjacent molecules is 3.9017 (17) Å, and the centroid–centroid distance between benzene and pyridine rings of adjacent molecules is 3.584 (2) Å. Intramolecular O—H⋯O hydrogen bonding is present.

Related literature

For general background on π–π stacking, see: Deisenhofer & Michel (1989 ▶). For π–π stacking in dihydroxybenzoate complexes, see: Yang et al. (2006 ▶); Zhang et al. (2008 ▶). For π–π stacking found in chlorobenzoate complexes, see: Maroszová et al. (2006 ▶); Malamatari et al. (1995 ▶); Wen & Ying (2007 ▶); Wen et al. (2007 ▶). For centroid-to-centroid distances between benzene rings in salicylate complexes, see: Allen (2002 ▶).

Experimental

Crystal data

[Zn(C₇H₄ClO₃)₂(C₁₂H₈N₂)(H₂O)]
M _r = 606.69
Triclinic,
a = 8.2611 (12) Å
b = 11.0124 (16) Å
c = 14.654 (2) Å
α = 100.534 (7)°
β = 94.360 (8)°
γ = 111.315 (5)°
V = 1206.1 (3) Å³
Z = 2
Mo Kα radiation
μ = 1.29 mm⁻¹
T = 294 K
0.28 × 0.20 × 0.12 mm

Data collection

Rigaku R-AXIS RAPID IP diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.86, T _max = 0.92
13131 measured reflections
4275 independent reflections
3695 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.101
S = 1.05
4274 reflections
343 parameters
H-atom parameters constrained
Δρ_max = 0.64 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002 ▶); program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811020435/ng5174sup1.cif

e-67-0m855-sup1.cif^{(20.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811020435/ng5174Isup2.hkl

e-67-0m855-Isup2.hkl^{(205.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Zn—O1	2.0155 (18)
Zn—O4	2.0325 (19)
Zn—O7	2.109 (2)
Zn—N1	2.130 (2)
Zn—N2	2.126 (2)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3A⋯O2	0.95	1.66	2.559 (3)	155
O6—H6A⋯O5	0.95	1.72	2.595 (3)	151
O7—H7A⋯O2	0.86	1.93	2.707 (3)	150
O7—H7B⋯O5	0.96	1.75	2.674 (3)	163

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Acknowledgments

This work was supported by the Natural Science Foundation of China (grant No. 20443003).

supplementary crystallographic information

Comment

As π-π stacking between aromatic rings plays an important role in the electron transfer process in some biological system (Deisenhofer & Michel, 1989), the π-π stacking has attracted our much attention in past years. In order to understand the nature of π-π stacking between aromatic rings, we have determined crystal structures of metal complexes with aromatic ligands to investigate the factors controlling aromatic stacking.

Our previous studies on dihydroxybenzoate complexes has revealed that hydroxy-substitution of the aromatic ring may be an effective factor for π-π stacking (Yang et al., 2006; Zhang et al., 2008). As a continued investigation, the title chlorine-substituted salicylate complex has been prepared in the laboratory and its crystal structure is presented here to show the effect of chlorine-substitution on π-π stacking between benzene rings of chlorine-substituted salicylates.

The molecular structure of the title compound is shown in Fig. 1. The Zn(II) cation is coordinated by one phenanthroline (phen) ligand, two chloro-salicylate (chls) anions and one water molecule in a distorted square-pyramidal coordination geometry (Table 1). The Zn atom is 0.4591 (12) Å deviated from the basal plane towards the apical O1 atom. Uncoordinated carboxyl oxygen atoms, O2 and O5, are simultaneously hydrogen bonded to the coordinated water molecule and hydroxyl group of the same chls anion (Table 2).

It is notable π-π stacking between benzene rings of chls anions in the crystal structure. A partially overlapped arrangement is observed between parallel chls anions of neighboring complexes (Fig. 2). The face-to-face separation between C14-benzene ring C14ⁱ-benzene ring is 3.449 (3) Å, and the centroid-to-centroid distance is 3.9003 (17) Å [symmetry code: (i) 1 - x, 1 - y, 2 - z]. These facts clearly indicate the existence of aromatic stacking between benzene rings of chls anions.

A partially overlapped arrangement is also observed between nearly parallel chls anion and phen ligands of neighboring complexes (Fig. 3). The centroid-to-centroid separation between C26-benzene and N1ⁱⁱ-phen is 3.5841 (18) Å [symmetry code: (ii) 2 - x, 1 - y, 1 - z], and that between C26-benznen and N2ⁱⁱⁱ-phen is 3.584 (2) Å [symmetry code: (iii) 1 - x, 1 - y, 1 - z]. These findings also suggest that the chls is involved in π-π stacking in the crystal structure; similar to that found in reported metal complexes with chls ligands (Maroszová et al., 2006; Malamatari et al., 1995; Wen & Ying, 2007; Wen et al., 2007).

As π-π stacking interaction does not occur between benzene ring in salicylate complexes (Allen, 2002), but occurs in the chloro-salicylate complex. This reveals the effect of chloro-substitution on aromatic π-π stacking.

Experimental

An ethanol solution (10 ml) of 1,10-phenanthroline (0.200 g, 1 mmol) was slowly added to an aqueous solution (5 ml) containing Zn(NO₃)₂.6H₂O (0.300 g, 1 mmol), 4-chloro-salicylic acid (0.170 g, 1 mmol) and Na₂CO₃ (0.053 g, 0.5 mmol) with continuous stirring. The above reaction mixture was refluxed for 4 h. After cooling to room temperature the solution was filtered. Single crystals were obtained from the filtrate by slow vaporization of solvent after 3 d.