N,N′-Bis(4-chloro­benzyl­idene)-3,3′-dimeth­oxy­biphenyl-4,4′-diamine

Ashokkumar Subashini; Kandasamy Ramamurthi; Helen Stoeckli-Evans

doi:10.1107/S1600536811015467

. 2011 May 7;67(Pt 6):o1296–o1297. doi: 10.1107/S1600536811015467

N,N′-Bis(4-chlorobenzylidene)-3,3′-dimethoxybiphenyl-4,4′-diamine

Ashokkumar Subashini ^a, Kandasamy Ramamurthi ^a,^*, Helen Stoeckli-Evans ^b

PMCID: PMC3120541 PMID: 21754702

Abstract

The title compound, C₂₈H₂₂Cl₂N₂O₂, crystallized with two independent molecules (A and B) in the asymmetric unit. The two molecules differ essentially in the orientation of the outer aromatic rings. These dihedral angles are 56.07 (13) and 27.62 (15) Å for molecules A and B, respectively. In the crystal, A molecules are related as centrosymmetric pairs through a weak π–π interaction [centroid–centroid distance = 3.6959 (15) Å]. There are also a number of intermolecular C—H⋯O, C—H⋯N and C—H⋯π interactions present.

Related literature

For early work on the synthesis of multidentate Schiff base ligands, see: Weber (1967 ▶); Lesser et al. (1975 ▶); Munro & Camp (2003 ▶). For examples of Schiff base metal complexes exhibiting biological properties, see: Golcu et al. (2005 ▶); Liu & Yang (2010 ▶). For examples of Schiff base metal complexes exhibiting catalytic properties, see: Daier et al. (2004 ▶). For details of photochromic properties of some Schiff base complexes, see: Zgierski & Grabowska (2000 ▶). For examples of some similar 4,4′-biphenyl diamine Schiff bases, see: Lesser et al. (1975 ▶); Aygun et al. (2004 ▶); Hou et al. (2006 ▶). For details of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₂₈H₂₂Cl₂N₂O₂
M _r = 489.38
Triclinic,
a = 9.2358 (5) Å
b = 11.8559 (6) Å
c = 23.5218 (12) Å
α = 75.810 (4)°
β = 80.326 (4)°
γ = 79.288 (4)°
V = 2433.1 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.30 mm⁻¹
T = 173 K
0.45 × 0.18 × 0.12 mm

Data collection

Stoe IPDS 2 diffractometer
Absorption correction: multi-scan (MULscanABS in PLATON; Spek, 2009 ▶) T _min = 0.772, T _max = 1.000
29251 measured reflections
9183 independent reflections
5705 reflections with I > 2σ(I)
R _int = 0.071

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.125
S = 0.98
9183 reflections
617 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2009 ▶); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2009 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97, PLATON and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811015467/fl2345sup1.cif

e-67-o1296-sup1.cif^{(36.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811015467/fl2345Isup2.hkl

e-67-o1296-Isup2.hkl^{(449.1KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811015467/fl2345Isup3.cml

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

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

Cg2, Cg5 and Cg7 are the centroids of the C8–C13, C29–C34 and C42–C47 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C23—H23⋯O4ⁱ	0.95	2.48	3.348 (4)	152
C31—H31⋯N1ⁱⁱ	0.95	2.57	3.498 (4)	166
C3—H3⋯Cg5ⁱⁱⁱ	0.95	2.75	3.642 (3)	156
C30—H30⋯Cg2ⁱⁱ	0.95	2.90	3.641 (3)	136
C33—H33⋯Cg7^iv	0.95	2.97	3.850 (3)	154

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

AS thanks the UGC, India, for the award of a Research Fellowship in Sciences for Meritorious Students [File No. 4–1/2008 (BSR)]. HSE thanks the staff of the XRD Application LAB., CSEM, Neuchâtel, for access to the X-ray diffraction equipment.

supplementary crystallographic information

Comment

Multidentate Schiff base ligands have been studied for many years (Weber, 1967; Lesser et al., 1975; Munro & Camp, 2003). Metal complexes of multidentate Schiff base ligands play an important role in the development of coordination chemistry and possess important properties, such as biological activity (Golcu et al., 2005; Liu & Yang, 2010), catalytic activity (Daier et al., 2004) and photochromic properties (Zgierski & Grabowska, 2000). Because of the structural characteristics of the Schiff base products (i.e. electron donor and acceptor groups connected to a π-conjugated chain), they will have potential as NLO or electro-optical materials. We present here the synthesis and crystal structure of the title 4,4'-biphenyl diamine Schiff base compound, prepared by the condensation reaction of 3,3'-dimethoxybenzidine with two equivalents of 4-chlorobenzaldehyde. There are a number of examples of similar Schiff bases in the Cambridge Structural Database (Allen, 2002); for example, 2,2'-Dibromo-4,4'-bis(p-methoxybenzilideneamine)biphenyl (Lesser et al., 1975), 3,3'Dimethoxybenzidene(2-hydroxybnzilidene)amino)biphenyl (Aygun et al., 2004) and 4,4'-bis(2,6-Dichlorobenzilideneamino)biphenyl (Hou et al., 2006).

The title compound crystallized with two independent molecules (A and B) in the asymmetric unit, Fig. 1. The 3,3'-dimethoxybiphenyl moieties in the two molecules have similar conformations, with the aromatic rings being inclined to one another by 36.12 (13) ° in molecule A and by 38.09 (13) ° in molecule B. A view of the Auto-fit figure (Fig. 2; Spek, 2009) of inverted molecule B on molecule A illustrates the difference in the conformation of the two molecules. The outer aromatic rings, Ring-1 (C1—C6) and Ring-4 (C21—C26), are inclined to one another by 56.05 (13) ° in molecule A, while in molecule B Ring-5 (C29—C34) and Ring-8 (49-C54) are inclined to one another by 27.62 (15) °. In molecule A Ring-1 (C1—C6) is inclined to Ring-2 (C14—C19) and Ring-3 (C21—C26) by 10.26 (13) and 56.07 (13) °, respectively. This is different to the situation in molecule B where Ring-5 (C29—C34) is inclined to Ring-7 (C42—C47) and Ring-8 (C49—C54) by 85.70 (13) and 27.62 (15) °, respectively.

In the crystal the A molecules stack head-to-tail with a separation of the Cl atoms, Cl1···Cl2ⁱ, of 3.5048 (12) Å (symmetry code (i) = x - 1, x + 2, x - 1). The B molecules stack head-to-head with a shorter separation of the Cl atoms; the distance Cl4···Cl4ⁱⁱ being 3.3173 (18) Å (symmetry code (ii) = -x - 1, -y + 3, -z). The crystal structure is further stabilized by intermolecular C–H···O and C–H···N hydrogen bonds (Table 1 and Fig. 3). The A molecules are related as centrosymmetric pairs through a weak π–π interaction [Cg2···Cg2ⁱ = 3.6959 (15) Å; Cg2 is the centroid of Ring-2 (C8—C13); Symmetry code: (i) -x, 1 - y, -z].

Footnote to Table 1: Cg2 is the centroid of Ring-2 (C8—C13); Cg5 is the centroid of Ring-5 (C29—C34); Cg7 is the centroid of Ring-7 (C42—C47).

Experimental

The title compound was synthesized by mixing 3,3'-dimethoxybenzidine and 4-chlorobenzaldehyde (molar ratio 1:2) in methanol at 343 K for 1 h. The mixture was then allowed to cool to RT giving a brown solid. Recrystallization from methanol gave brown rod-shaped crystals of the title compound suitable for X-ray diffraction analysis.