An octa­nuclear zinc(II) complex with 6,6′-dihydr­oxy-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­idyne)]diphenol

Naser Eltaher Eltayeb; Siang Guan Teoh; Suchada Chantrapromma; Hoong-Kun Fun; Rohana Adnan

doi:10.1107/S1600536808017340

. 2008 Jun 13;64(Pt 7):m912–m913. doi: 10.1107/S1600536808017340

An octanuclear zinc(II) complex with 6,6′-dihydroxy-2,2′-[1,2-phenylenebis(nitrilomethylidyne)]diphenol

Naser Eltaher Eltayeb ^a,^‡, Siang Guan Teoh ^a, Suchada Chantrapromma ^b,^§, Hoong-Kun Fun ^c,^*, Rohana Adnan ^a

PMCID: PMC2961853 PMID: 21202773

Abstract

The asymmetric unit of the title compound, tetraaquatetrakis{μ₃-6,6′-dioxido-2,2′-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}octazinc(II) dimethyl sulfoxide tetrasolvate dihydrate, [Zn₈(C₂₀H₁₂N₂O₄)₄(H₂O)₄]·4C₂H₆OS·2H₂O, contains one quarter of a Zn^II octanuclear complex with Inline graphic symmetry, one dimethyl sulfoxide molecule and one half of a water molecule which lies on a twofold rotation axis. The Zn^II atoms of the octanuclear complex have two different five-coordinate environments, viz. ZnN₂O₃ and ZnO₅. All eight Zn^II centers adopt a distorted square-pyramidal coordination; four Zn^II ions have the N₂O₂ tetradentate Schiff base ligand bound in a basal plane and the coordinated water molecule occupying the apical site, while the remaing four Zn^II ions are bound by five O atoms from three Schiff base ligands. In the crystal structure, Zn^II complex molecules, coordinated and uncoordinated water molecules and dimethyl sulfoxide molecules are linked via O—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π interactions, forming a three-dimensional framework.

Related literature

For related literatures on Schiff base Zn^II coordination complexes, see: Basak et al. 2007 ▶; Collinson & Fenton (1996 ▶); Pal et al. (2005 ▶); Tarafder et al. (2002 ▶). For related structures, see: Eltayeb et al. (2007a ▶,b ▶,c ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

[Zn₈(C₂₀H₁₂N₂O₄)₄(H₂O)₄]·4C₂H₆OS·2H₂O
M _r = 2321.03
Tetragonal,
a = 18.1324 (3) Å
c = 13.3813 (3) Å
V = 4399.56 (14) Å³
Z = 2
Mo Kα radiation
μ = 2.32 mm⁻¹
T = 100.0 (1) K
0.57 × 0.13 × 0.10 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.352, T _max = 0.796
26700 measured reflections
5851 independent reflections
3700 reflections with I > 2σ(I)
R _int = 0.085

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.138
S = 1.02
5851 reflections
314 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.67 e Å⁻³
Δρ_min = −1.34 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808017340/ci2611sup1.cif

e-64-0m912-sup1.cif^{(27KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808017340/ci2611Isup2.hkl

e-64-0m912-Isup2.hkl^{(286.5KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W1⋯O4ⁱ	0.84 (4)	1.72 (4)	2.535 (4)	164 (5)
O2W—H1W2⋯O5	0.85 (8)	2.28 (9)	3.032 (4)	147 (4)
O1W—H2W1⋯O5	0.83 (4)	1.95 (4)	2.772 (5)	174 (4)
C3—H3A⋯O3ⁱⁱ	0.93	2.57	3.271 (5)	132
C21—H21C⋯O4ⁱⁱⁱ	0.96	2.52	3.454 (7)	165
C21—H21B⋯Cg1^iv	0.96	2.81	3.475 (6)	127

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg1 is the centroid of the C1–C6 ring.

Acknowledgments

The authors thank the Malaysian Government, the Ministry of Science, Technology and Innovation, Malaysia (MOSTI) and Universiti Sains Malaysia for the E-Science Fund research grant (PKIMIA/613308) and facilities. The International University of Africa (Sudan) is acknowledged for providing study leave to NEE. SC thanks Prince of Songkla University for generous support. The authors also thank Universiti Sains Malaysia for the Research University Golden Goose Grant No. 1001/PFIZIK/811012.

supplementary crystallographic information

Comment

There has been considerable interest in the synthesis of metal Schiff base complexes due to their coordination chemistry and applications (Basak et al., 2007; Eltayeb et al., 2007a,b,c; Pal et al., 2005; Tarafder et al., 2002). Zinc complexes with Schiff bases are important in biological systems and coordination chemistry (Collinson & Fenton, 1996; Tarafder et al., 2002). Previously, we have reported crystal structures of Zn^II complexes with Schiff base ligands (Eltayeb et al., 2007a,b,c). As a continuation of our research on Schiff base complexes, we report here the crystal structure of the title octanuclear Zn^II complex.

The asymmetric unit of the title compound (Fig. 1) contains one quarter of the Zn₈(C₈₀H₅₆N₈O₂₀) complex, one dimethyl sulfoxide (C₂H₆OS) and one-half of a water molecule with its O atom lying on a twofold rotation axis. The other three quarters of the octanuclear complex molecule are generated by the fourfold axis. The Zn^II atoms of the octanuclear complex has two different five-coordination environments viz. ZnN₂O₃ and ZnO₅ (Fig. 2). All eight Zn^II centers adopt a distorted square-pyramidal coordination in which four Zn^II ions (outer) (Zn1 and its three symmetry equivalents Zn1A, Zn1B and Zn1C) coordinate with the N₂O₂ tetradentate Schiff base ligand bounded in a basal plane and the coordinated water molecule occupying the apical site. The other four Zn^II ions (inner) (Zn2 and its three symmetry equivalents Zn2A, Zn2B and Zn2C) are coordinated with five O atoms from three Schiff base ligands (see Fig. 2). The Zn^II ions in each unit are connected by one µ-O (Zn1—O2—Zn2) atom (Fig. 1). The Zn—µ-O bond lengths are Zn1—O2 = 2.032 (3) and Zn2—O2 = 2.191 (3) Å. In the octanuclear cluster, the µ-O1 atoms are also in bridging positions, between the Zn^II ions (inner cavity) (Zn2—O1—Zn2B) with the Zn—µ-O distances of Zn2—O1 = 2.000 (3) Å and Zn2B—O1 = 1.981 (3) Å. The connections of the four inner Zn^II ions by bridging µ-O1 and its equivalents result in the formation of an eight membered ring (Zn2—O1—Zn2B—O1B—Zn2C—O1C—Zn2A—O1A), with the Zn···Zn contacts being 3.4878 (5) Å. The Schiff base ligand in the present complex is in an umbrella conformation with the dihedral angle between the two outer rings (C1—C6 and C15—C20) being 48.1 (2) °. In the octanuclear complex (Fig. 2), the four Schiff bases have their concave sides alternating up and down. The coordination geometry of the five-coordinate atoms Zn1 and Zn2 (and their equivalents) can be viewed as that of a slightly distorted square antiprism. Bond lengths and angles observed in the structure are in normal ranges (Allen et al., 1987) and comparable with the related structures (Eltayeb et al., 2007a,b,c).

In the crystal packing (Fig. 3), the Zn^II complex molecules, coordinated and free water molecules and dimethyl sulfoxide molecules are linked via O—H···O and C—H···O hydrogen bonds and C—H···π interactions involving the C1—C6 (centroid Cg1) ring (Table 1) forming a three-dimensional framework.

Experimental

The title compound was synthesized by adding 2,3-dihydroxybenzaldehyde (0.552 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 30 min. Zinc chloride (0.544 g, 4 mmol) in ethanol (10 ml) was then added, followed by triethylamine (1.0 ml, 7.2 mmol). The mixture was stirred at room temperature for 3 h. The yellow precipitate obtained was washed with about 5 ml e thanol, dried, and then washed with copious amounts of diethylether. Orange single crystals of the title compound suitable for X-ray diffraction were formed after recrystallization in the dimethyl sulfoxide/ethanol (3:5 v/v) at room temperature after several days.