{4,4′-Dimeth­oxy-2,2′-[1,1′-(ethane-1,2-diyldinitrilo)diethyl­idyne]diphenolato}nickel(II) hemihydrate

Hoong-Kun Fun; Reza Kia

doi:10.1107/S1600536808023362

. 2008 Jul 31;64(Pt 8):m1081–m1082. doi: 10.1107/S1600536808023362

{4,4′-Dimethoxy-2,2′-[1,1′-(ethane-1,2-diyldinitrilo)diethylidyne]diphenolato}nickel(II) hemihydrate

Hoong-Kun Fun ^a,^*, Reza Kia ^a,^‡

PMCID: PMC2961936 PMID: 21203060

Abstract

In the title complex, [Ni(C₂₀H₂₂N₂O₄)]·0.5H₂O, the Ni^II ion is in a slightly distorted square-planar geometry involving an N₂O₂ atom set of the tetradentate Schiff base ligand. The asymmetric unit contains one molecule of the complex and half a water solvent molecule. The solvent water molecule lies on a crystallographic twofold rotation axis. An intermolecular O—H⋯O hydrogen bond forms an R ₂ ¹(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex. In the crystal structure, molecules are linked by π–π stacking interactions, with centroid–centroid distances in the range 3.5310 (11)–3.7905 (12) Å, forming extended chains along the b axis. In addition, there are Ni⋯Ni and Ni⋯N interactions [3.4404 (4)–4.1588 (4) and 3.383 (2)–3.756 (2) Å, respectively] which are shorter than the sum of the van der Waals radii of the relevant atoms. Further stabilization of the crystal structure is attained by weak intermolecular C—H⋯O and C—H⋯π interactions.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For related structures see, for example: Clark et al. (1968 ▶, 1969 ▶, 1970 ▶); Hodgson (1975 ▶). For applications and bioactivities see, for example: Elmali et al. (2000 ▶); Blower (1998 ▶); Granovski et al. (1993 ▶); Li & Chang (1991 ▶); Shahrokhian et al. (2000 ▶); Fun & Kia (2008 ▶).

Experimental

Crystal data

[Ni(C₂₀H₂₂N₂O₄)]·0.5H₂O
M _r = 422.11
Monoclinic,
a = 29.1721 (7) Å
b = 7.3032 (2) Å
c = 17.2833 (4) Å
β = 101.323 (1)°
V = 3610.53 (16) Å³
Z = 8
Mo Kα radiation
μ = 1.11 mm⁻¹
T = 100.0 (1) K
0.33 × 0.18 × 0.15 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.712, T _max = 0.853
21087 measured reflections
5319 independent reflections
4166 reflections with I > 2˘I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.051
wR(F ²) = 0.138
S = 1.04
5319 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 1.43 e Å⁻³
Δρ_min = −0.90 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/S1600536808023362/lh2663sup1.cif

e-64-m1081-sup1.cif^{(23.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808023362/lh2663Isup2.hkl

e-64-m1081-Isup2.hkl^{(260.6KB, hkl)}

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

Table 1. Selected geometric parameters (Å, °).

Ni1—O2	1.8201 (16)
Ni1—O1	1.8315 (15)
Ni1—N1	1.8575 (19)
Ni1—N2	1.8617 (19)

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Ni1⋯Ni1ⁱ	3.4404 (4)
Ni1⋯Ni1ⁱⁱ	4.1588 (4)
Ni1⋯N1ⁱ	3.383 (2)
Ni1⋯N2ⁱ	3.756 (2)
Ni1⋯N2ⁱⁱ	3.728 (2)
Cg1⋯Cg3ⁱⁱⁱ	3.7905 (12)
Cg3⋯Cg4^iv	3.5310 (11)
Cg4⋯Cg4ⁱⁱⁱ	3.6152 (11)

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O2—Ni1—O1	81.89 (7)
O2—Ni1—N1	175.30 (8)
O1—Ni1—N1	94.47 (8)
O2—Ni1—N2	93.96 (8)
O1—Ni1—N2	175.13 (8)
N1—Ni1—N2	89.81 (8)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg1, Cg3, and Cg4 are the centroids of the C11–C16, Ni1-O1-C1-C6-C7-N1 and Ni1-O2-C16-C11-C10-N2 rings, respectively.

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W1⋯O1	0.84	2.41	3.1173 (19)	143
O1W—H1W1⋯O2	0.84	2.21	2.9077 (16)	141
C8—H8A⋯O2ⁱ	0.97	2.47	3.319 (3)	146
C9—H9A⋯O1Wⁱⁱ	0.97	2.52	3.407 (3)	152
C18—H18B⋯Cg1^iv	0.96	2.71	3.385 (2)	127
C19—H19C⋯Cg2^iv	0.96	2.81	3.652 (3)	146

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Symmetry codes: (i) Inline graphic ; (ii) ; (iv) . Cg1 and Cg2 are centroids of the C11–C16 and C1–C6 benzene rings, respectively.

Acknowledgments

HKF and RK thank the Malaysian Government and Universiti sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Schiff base complexes are some of the most important stereochemical models in transition metal coordination chemistry, with their ease of preparation and structural variations (Granovski et al., 1993). Transition metal complexes of Schiff base ligands are always of interest since they exhibit a marked tendency to oligomerize, thus leading to novel structural types, and also display a wide variety of magnetic properties. Many of the reported structural investigations of these complexes are discussed in some details in a review (Hodgson, 1975). Metal derivatives of Schiff bases have been studied extensively, and Cu(II) and Ni(II) complexes play a major role in both synthetic and structural research (Elmali et al., 2000; Blower, 1993; Fun & Kia, 2008; Granovski et al., 1993; Li & Chang, 1991; Shahrokhian et al., 2000). Tetradentate Schiff base metal complexes may form trans or cis planar or tetrahedral structures (Elmali et al., 2000).

In the title compound (I, Fig. 1), the Ni^II ion shows a sligthly distorted square-planar geometry which is coordinated by two imine N atoms and two phenol O atoms of the tetradentate Schiff base ligand. An intermolecular O—H···O hydrogen bond forms a four-membered ring, producing a R¹₂(4) ring motif (Bernstein et al., 1995). The bond lengths are within the normal ranges (Allen et al., 1987). The asymmetric unit of the compound contains one molecule of the complex, and one-half of the water solvent. The latter shows bifurcated hydrogen bond which is connected to the phenolato oxygen atoms of the complex. Atoms C8 and C9 are significantly out of the plane, as indicated by the torsion angle N1–C8–C9–N2, which is -23.6 (3)°. The dihedral angle betwen two benzene rings is 5.13 (11)°. In the crystal structure, (Fig. 2), the molecules are form 1-D extended chains along the b axis with Ni···Ni and Ni···N separations (Table 2) of 3.4404 (4) – 4.1588 (4), and 3.383 (2) – 3.756 (2) Å, and short intermolecular distances between the centroids of the six-membered rings [3.5310 (11) – 3.7905 (12) Å], respectively. The Ni···Ni dimeric separations are significantly shorter than the sum of the van der Waals radii of two Ni atoms (4.60 Å). The crystal packing is stabilized by intermolecular O—H···O (x 2), and C—H···O (x 2) hydrogen bonds, and weak intermolecular C—H···π interactions.

Experimental

A chloroform solution (40 ml) of the ligand (1 mmol, 354 mg) was added to a methanol solution (20 ml) of NiCl₂.6H₂O (1.05 mmol, 237 mg). The mixture was refluxed for 30 min and then filtered. After keeping the filtrate in air for 4 d, red block-shaped crystals were formed at the bottom of the vessel on slow evaporation of the solvent.