6,6′-Diethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]diphenol

Hoong-Kun Fun; Hadi Kargar; Reza Kia; Arezoo Jamshidvand

doi:10.1107/S1600536809007557

. 2009 Mar 6;65(Pt 4):o707–o708. doi: 10.1107/S1600536809007557

6,6′-Diethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]diphenol

Hoong-Kun Fun ^a,^*, Hadi Kargar ^b,^‡, Reza Kia ^a, Arezoo Jamshidvand ^b

PMCID: PMC2969095 PMID: 21582445

Abstract

In the crystal structure, the title Schiff base compound, C₂₃H₃₀N₂O₄, exhibits crystallographic twofold rotation symmetry. The imino group is coplanar with the aromatic ring with an N—C—C—C torsion angle of -179.72 (9)°. An intramolecular O—H⋯N hydrogen bond forms a six-membered ring, producing an S(6) ring motif. The dihedral angle between symmetry related benzene rings is 28.05 (5)°. The ethoxy group makes a C—O—C—C torsion angle of −7.20 (16)° with the benzene ring. The crystal structure is stabilized by intermolecular 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 information on Schiff base ligands, complexes and their applications, see, for example: Calligaris & Randaccio, (1987 ▶); Casellato & Vigato, (1977 ▶); Pal et al. (2005 ▶); Reglinski et al. 2004 ▶; Hou et al. (2001 ▶); Ren et al. (2002 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₃H₃₀N₂O₄
M _r = 398.49
Monoclinic,
a = 5.6523 (1) Å
b = 12.9591 (2) Å
c = 28.3771 (3) Å
β = 91.282 (1)°
V = 2078.07 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.43 × 0.22 × 0.04 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.880, T _max = 0.997
21349 measured reflections
3560 independent reflections
2743 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.128
S = 1.07
3560 reflections
134 parameters
H-atom parameters constrained
Δρ_max = 0.42 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; 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, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809007557/at2735sup1.cif

e-65-0o707-sup1.cif^{(17.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809007557/at2735Isup2.hkl

e-65-0o707-Isup2.hkl^{(174.7KB, 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
O1—H1⋯N1	0.82	1.85	2.5772 (12)	147
C11—H11A⋯Cg1ⁱ	0.96	2.87	3.6007 (12)	133

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Symmetry code: (i) Inline graphic . Cg1 is the centroid of the C1–C6 benzene ring.

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 the award of a post-doctoral research fellowship. HK and AJ thank PNU for financial support. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.

supplementary crystallographic information

Comment

The condensation of primary amines with carbonyl compounds yields Schiff base (Casellato & Vigato, 1977) that are still now regarded as one of the most potential group of chelators for facile preparations of metallo-organic hybrid materials. In the past two decades, the synthesis, structure and properties of Schiff base complexes have stimulated much interest for their noteworthy contributions in single molecule-based magnetism, materials science, catalysis of many reactions like carbonylation, hydroformylation, reduction, oxidation, epoxidation and hydrolysis, etc (Pal et al., 2005; Reglinski et al., 2004; Hou et al., 2001; Ren et al., 2002). This is due to the fact that Schiff bases offer opportunities for inducing substrate chirality, tuning the metal-centered electronic factor and enhancing the solubility and stability of either homogeneous or heterogeneous catalysts. Only a relatively small number of free Schiff base ligands have been characterized (Calligaris & Randaccio, 1987). As an extension of our work on the structural characterization of Schiff base compounds, the title compound, is reported here.

The molecule of the title compound, (Fig. 1), has a crystallographic twofold rotation symmetry. The atom C9 lies across a crystallographic twofold rotation symmetry. An intramolecular O—H···N hydrogen bond forms a six-membered ring, producing a S(6) ring motif (Bernstein et al. 1995). The dihedral angle between the symmetry related benzene rings is 28.05 (5)°. The ethoxy group makes a torsion angle (C11—O2—C2—C3) of -7.20 (16)° with the benzene ring. The N atom is in close proximity to the H atom of the methylene group of the diamine segment, with H8B—N1 distance of 2.70 Å. The crystal structure is stabilized by intermolecular C—H···π interactions [Cg1 is the centroid of the C1–C6 benzene ring] (Table 1).

Experimental

The synthetic method has been described earlier (Reglinski et al., 2004), except that 3-ethoxysalicylaldehyde was used. Single crystals suitable for X-ray diffraction were obtained by evaporation of an methanol solution at room temperature.