N,N′-Bis[2-chloro-5-(trifluoro­meth­yl)benzyl­idene]ethane-1,2-diamine

Hoong-Kun Fun; Reza Kia

doi:10.1107/S1600536808024926

. 2008 Aug 9;64(Pt 9):o1722–o1723. doi: 10.1107/S1600536808024926

N,N′-Bis[2-chloro-5-(trifluoromethyl)benzylidene]ethane-1,2-diamine

Hoong-Kun Fun ^a,^*, Reza Kia ^a,^‡

PMCID: PMC2960650 PMID: 21201706

Abstract

The molecule of the title Schiff base compound, C₁₈H₁₂Cl₂F₆N₂, adopts an E configuration with respect to the azomethine C=N bond. Intramolecular C—H⋯F (× 2) and C—H⋯Cl (× 2) hydrogen bonds generate S(5) ring motifs. The imino group is coplanar with the aromatic ring. Within the molecule, the planar units are parallel, but extend in opposite directions from the methylene bridge, as indicated by the dihedral angle between the two benzene rings of 3.74 (6)°. The interesting features of the crystal structure are weak intermolecular Cl⋯N and F⋯F interactions, with distances of 2.9192 (11) and 3.2714 (10) Å, respectively, which are shorter than the sum of the van der Waals radii of the relevent atoms. These interactions link neighbouring molecules into dimers which are stacked down the b axis.

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: see, for example: Fun, Kargar & Kia (2008 ▶); Fun, Kia & Kargar (2008 ▶); Fun, Mirkhani et al. (2008a ▶,b ▶); Calligaris & Randaccio (1987 ▶). For information on Schiff base complexes and their applications, see, for example: Kia, Mirkhani, Kalman & Deak (2007 ▶); Kia, Mirkhani, Harkema & van Hummel (2007 ▶); Pal et al. (2005 ▶); Hou et al. (2001 ▶); Ren et al. (2002 ▶).

Experimental

Crystal data

C₁₈H₁₂Cl₂F₆N₂
M _r = 441.20
Monoclinic,
a = 35.7299 (8) Å
b = 4.6663 (1) Å
c = 27.1134 (6) Å
β = 127.851 (2)°
V = 3569.44 (17) Å³
Z = 8
Mo Kα radiation
μ = 0.43 mm⁻¹
T = 100.0 (1) K
0.59 × 0.27 × 0.15 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.786, T _max = 0.938
61787 measured reflections
7964 independent reflections
6400 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.111
S = 1.10
7964 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.40 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/S1600536808024926/at2608sup1.cif

e-64-o1722-sup1.cif^{(20.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808024926/at2608Isup2.hkl

e-64-o1722-Isup2.hkl^{(389.7KB, 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
C3—H3A⋯F3	0.93	2.43	2.7415 (14)	100
C7—H7A⋯Cl1	0.93	2.71	3.0811 (12)	105
C10—H10A⋯Cl2	0.93	2.72	3.0925 (13)	105
C16—H16A⋯F5	0.93	2.40	2.7325 (13)	101

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Symmetry codes: .

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.

supplementary crystallographic information

Comment

Schiff bases are one of most prevalent mixed-donor ligands in the field of coordination chemistry. There has been growing interest in Schiff base ligands, mainly because of their wide application in the field of biochemistry, synthesis, and catalysis (Kia et al., 2007a,b; Pal et al., 2005; Hou et al., 2001; Ren et al., 2002). Many Schiff base complexes have been structurally characterized, but only a relatively small number of free Schiff bases have been characterized (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 molecule of the title compound, (I), (Fig. 1), adopts an E configuration with respect to the azomethine C═N bond. The bond lengths and angles are within normal ranges (Allen et al., 1987). Intramolecular C—H···F (x 2) and C—H···Cl (x 2) hydrogen bonds generate S(5) ring motifs (Bernstein et al., 1995). The two planar units are parallel but extend in opposite directions from the methylene bridge. The dihedral angle between two benzene rings is 3.74 (6)°. The interesting feature of the crystal structure is weak intermolecular Cl···N and F···F interactions with the distances of 2.9192 (11) and 3.2714 (10) Å, which are shorter than the sum of the van der Waals radii of the relevant atoms, respectively (Table 1). These interactions link neighbouring molecules into dimers which are stacked down the b-axis (Fig. 2).

Experimental

The synthetic method has been described earlier (Fun, Mirkhani et al., (2008a,b)). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.