N,N′-Bis(5-bromo-2-hydroxy­benzyl­idene)-2,2-dimethylpropane-1,3-diamine

Hoong-Kun Fun; Reza Kia; Hadi Kargar

doi:10.1107/S160053680802816X

. 2008 Sep 6;64(Pt 10):o1895–o1896. doi: 10.1107/S160053680802816X

N,N′-Bis(5-bromo-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine

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

PMCID: PMC2959295 PMID: 21201107

Abstract

The crystal structure of the title Schiff base compound, C₁₉H₂₀Br₂N₂O₂, contains two crystallographically independent molecules (A and B) in the asymmetric unit, with similar conformations. Intramolecular O—H⋯N (× 4) and C—H⋯N (× 5) hydrogen bonds form six- and five-membered rings, producing S(6) and S(5) ring motifs, respectively. One of the N atoms in molecule A acts as a trifurcated acceptor, the rest of the N atoms being bifurcated acceptors. The dihedral angles between the benzene rings in molecules A and B are 47.83 (17) and 61.11 (17)°, respectively. The molecular conformation is stabilized by intramolecular O—H⋯N and C—H⋯N hydrogen bonds. The short distances between the centroids of the benzene rings [3.7799 (19)–3.890 (2) Å] indicate the existence of π–π interactions. In addition, the crystal structure is further stabilized by an intermolecular C—H⋯O hydrogen bond, C—H⋯π interactions, and short intermolecular Br⋯Br and Br⋯O contacts [3.4786 (5) and 3.149 (3) Å, respectively].

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 and complexes and their applications, see, for example: Fun, Kargar & Kia (2008 ▶); Fun, Kia & Kargar (2008 ▶); Fun, Mirkhani et al. (2008a ▶,b ▶); Calligaris & Randaccio (1987 ▶); Casellato & Vigato (1977 ▶); Pal et al. (2005 ▶); Reglinski et al. 2004 ▶; Hou et al. (2001 ▶); Ren et al. (2002 ▶).

Experimental

Crystal data

C₁₉H₂₀Br₂N₂O₂
M _r = 468.19
Monoclinic,
a = 31.7684 (10) Å
b = 6.2436 (2) Å
c = 38.7287 (11) Å
β = 99.870 (2)°
V = 7568.1 (4) Å³
Z = 16
Mo Kα radiation
μ = 4.30 mm⁻¹
T = 100.0 (1) K
0.52 × 0.10 × 0.06 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.213, T _max = 0.782
47391 measured reflections
11172 independent reflections
6920 reflections with I > 2σ(I)
R _int = 0.080

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.110
S = 1.01
11172 reflections
463 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.57 e Å⁻³
Δρ_min = −0.46 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, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680802816X/at2626sup1.cif

e-64-o1895-sup1.cif^{(30.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802816X/at2626Isup2.hkl

e-64-o1895-Isup2.hkl^{(546.4KB, 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
O1B—H1OB⋯N1B	0.85	1.81	2.580 (4)	151
O2A—H2OA⋯N2A	0.85 (4)	1.79 (4)	2.578 (4)	154 (4)
O1A—H1OA⋯N1A	0.79 (5)	1.85 (5)	2.572 (4)	153 (4)
O2B—H2OB⋯N2B	0.73 (5)	1.94 (5)	2.586 (4)	149 (5)
C8A—H8AA⋯N2A	0.99	2.58	2.960 (4)	103
C8B—H8BA⋯N2B	0.99	2.60	2.966 (4)	102
C16B—H16B⋯O2Bⁱ	0.95	2.58	3.290 (5)	131
C19A—H19B⋯N1A	0.98	2.58	2.918 (4)	100
C19A—H19C⋯N2A	0.98	2.58	2.933 (5)	101
C19B—H19F⋯N1B	0.98	2.60	2.926 (5)	100
C7B—H7BA⋯Cg1ⁱⁱ	0.95	2.96	3.571 (4)	123
C18B—H18D⋯Cg2ⁱⁱⁱ	0.98	2.77	3.652 (4)	151

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) . Cg1 and Cg2 are the centroids of the C1A–C6A and C12A–C17A 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 an award of a post-doctoral research fellowship. HK thanks PNU for financial support.

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). Only a relatively small number of free Schiff base ligands have been characterized by X-ray crystallography (Calligaris & Randaccio, 1987). As an extension of our work (Fun, Kargar & Kia, 2008; Fun, Kia & Kargar, 2008; Fun, Mirkhani et al., 2008a,b) on the structural characterization of Schiff base compounds, the title compound (I), is reported here.

The crystal structure of the title compound (I) (Fig. I), contains two crystallographically independent molecules (A and B) in the asymmetric unit, with similar conformations. The bond lengths and angles are within normal ranges (Allen et al., 1987). Intramolecular O—H···N (x 4) and C—H···N (x 5) hydrogen bonds form six- and five-membered rings, producing S(6) and S(5) ring motifs, respectively (Bernstein et al. 1995) (Table 1). One of the nitrogen atoms in the molecule A acts as a trifurcated acceptor, but the rest of the nitrogen atoms are bifurcated acceptors. The dihedral angles between the benzene rings in molecule A and B is 47.83 (17)° and 61.11 (17)°. The molecular conformation is stabilized by intramolecular O—H···N and C—H···N hydrogen bonds. The short distances between the centroids of the benzene rings [Cg2–Cg2 = 3.7799 (19) Å and Cg3–Cg3 = 3.890 (2) Å] indicate the existence of π–π interactions. The Cg2 and Cg3 are the centroids of the C12A–C17A and C12B–C17B benzene rings. The interesting features of the crystal structure are short intermolecular Br···Br [symmetry code: 1/2 + x, -1/2 - y + 1/2 + z] and Br···O [symmetry code: -x, 1 + y, 1/2 - z] interactions, with distances of 3.4786 (5) and 3.149 (3) Å, respectively, which are significantly shorter than the sum of the van der Waals radii of the relevent atoms.

In addition, the crystal structure is further stabilized by intermolecular C—H···O hydrogen bond and C—H···π interactions.

Experimental

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