Crystal structure of BIS[2-((E)-(p-tolylimino) methyl)-6-bromo-4- chlorophenol]copper(II)

Article abstract of DOI:10.1134/S0022476612030286

A new complex CuL₂ 1 [HL = 2-((E)-(p-tolylimino) methyl)-6-bromo-4-chlorophenol] is obtained and characterized using the single crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, P2₁/c space group, with a = 13.3203(13) A, b = 12.3052(11) A, c = 17.8664(17) A, β = 105.3420(10)°, V = 2824.1(5) A³, Z = 4, Dc = 1.672 g/cm³, R₁ = 0.0686. The geometry around copper(II) is intermediate between square planar and tetrahedral. The units of the complex are linked via weak intermolecular Br...Br contracts, leading to the formation of one-dimension (1D) chains along the b axis; the multipoint Cu...Cl intermolecular interactions extend the 1D chain into a 2D layer. Original Russian Text Copyright

Full text of DOI:10.1134/S0022476612030286

Journal of Structural Chemistry. Vol. 53, No. 3, pp. 603-605, 2012
Original Russian Text Copyright © 2012 by X. H. Pu
CRYSTAL STRUCTURE OF BIS[2-((E)-(p-TOLYLIMINO)
METHYL)-6-BROMO-4-CHLOROPHENOL]COPPER(II)
© X. H. Pu
UDC 548.73:541.49:546.56:548.737
A new complex CuL2 1 [HL = 2-((E)-(p-tolylimino) methyl)-6-bromo-4-chlorophenol] is obtained and
characterized using the single crystal X-ray diffraction analysis. The crystal belongs to the monoclinic
system, P21/c space group, with a = 13.3203(13) Å, b = 12.3052(11) Å, c = 17.8664(17) Å, β =
3
3
105.3420(10)°, V = 2824.1(5) Å , Z = 4, Dc = 1.672 g/cm , R1 = 0.0686. The geometry around copper(II) is
intermediate between square planar and tetrahedral. The units of the complex are linked via weak inter-
molecular Br…Br contracts, leading to the formation of one-dimension (1D) chains along the b axis; the
multipoint Cu…Cl intermolecular interactions extend the 1D chain into a 2D layer.
Keywords: copper(II) complexes, single crystal X-ray analysis.
Copper is an important element that is essential for life; it exists in some native enzymes and is required by all
organisms. Due to their important biological relevance, many copper complexes have been reported in recent years [1-4].
Among these complexes, Schiff′s base complexes have been widely studied because of their industrial and biological
applications [5-7]. In this paper, the complex bis[2-((E)-(p-tolylimino)methyl)-6-bromo-4-chlorophenol]copper(II) is
obtained from the reaction of 2-((E)-(p-tolylimino)methyl)-6-bromo-4-chlorophenol] and CuCl2⋅2H2O. A single crystal X-ray
analysis of the complex is undertaken to elucidate its conformation and structure.
3
Experimental. To a solution of 3-bromo-5-chloro-2-hydroxybenzaldehyde (0.002 mol) in EtOH (10 cm ) a solution
3
3
of p-toluidine (0.002 mol) in EtOH (10 cm ) was added followed by CuCl2⋅2H2O (0.001 mol) in EtOH (10 cm ). The mixture
was stirred for about 30 min at room temperature to give a clear brown solution. After keeping this solution in air for 7 days,
greenish brown block-shaped crystals were formed at the bottom of the vessel by slowly evaporating the solvent (scheme 1).
The crystals was filtered, washed with cold EtOH, and dried in vacuum desiccator using anhydrous CaCl2 (yield 70%).
Scheme 1. Synthesis of the complex
Department of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Shaanxi, China;
pxh913@163.com. The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 53, No. 3, pp. 608-
610, May-June, 2012. Original article submitted February 24, 2011.
0022-4766/12/5303-0603
603

Fig. 1. View of the complex, showing 30% probability
displacement ellipsoids (arbitrary spheres for the H
atoms).
TABLE 1. Selected Bond Lengths (Å) and Bond Angles (deg)
Bond
Å
Bond
Å
Angle
deg
Angle
deg
Cu(1)–O(1)
Cu(1)–O(2)
Cu(1)–N(2)
1.885(6)
1.893(6)
2.004(7)
Cu(1)–N(1)
Br(1)–C(4)
Cl(1)–C(6)
1.995(6) O(1)–Cu(1)–O(2) 154.4(3) O(1)–Cu(1)–N(2) 91.5(3)
1.892(9) O(1)–Cu(1)–N(1) 93.5(3) O(2)–Cu(1)–N(2) 93.0(3)
1.772(10) O(2)–Cu(1)–N(1) 92.0(3) N(1)–Cu(1)–N(2) 157.6(3)
A crystal of CuL2 with the dimensions of 0.47×0.45×0.40 mm was mounted on a glass fiber in a random orientation.
The data were collected by a Bruker Smart 1000 CCD diffractometer equipped with a graphite-monochromatized MoKα
radiation (λ = 0.71073 Å) in the range of 2.29 ≤ θ ≤ 25.02. The crystal belongs to the monoclinic system, P2(1)/c space
3
group, with a = 13.3203(13) Å, b = 12.3052(11) Å, c = 17.8664(17) Å, β = 105.3420(10)°, V = 2824.1(5) Å , Z = 2, Dc =
3
–1
1.672 g/cm , μ(MoKα) = 3.821 mm , F(000) = 1404, S = 1.024. Final values of the divergence factors were: R1 = 0.1415,
wR2 = 0.1987 for all reflections and R1 = 0.0686, wR2 = 0.1686 for 4968 reflections with I > 2σ(I ) used in the calculations.
Semi-empirical absorption correction was applied. The structure was solved using the direct methods and refined by full-
matrix least-squares techniques on F 2 using the SHELXTL-97 program package [8].The main interatomic distances and bond
angles are listed in Table 1. The structural data for complex 1 were deposited in the Cambridge Crystallographic Data Center
under the No. CCDC 799982.
Results and discussion. The X-ray diffraction analysis of complex 1 shows, that the copper ion is bonded to the
oxygen and nitrogen donor atoms of two bidentate ligand molecules in the usual trans arrangement (Fig. 1). The geometry
around copper(II) in 1 is intermediate between square planar and tetrahedral, where the dihedral angle between the two
coordination planes defined by O(1)–Cu(1)–N(1) and O(2)–Cu(1)–N(2) is 33.4°. It is interesting to note that a similar
complex bis-{(diphenylmethyl)[(2-oxo-1H-benzo-1-yl-idene)-methyl]aminato}copper(II) shows a similar dihedral angle
between O–Cu–N of 38.6°. The difference indicates that the phenylmethyl substituent has a smaller steric effect than the
diphenylmethyl substituent on the geometry of these complexes [9]. Bond angles also show that the coordination geometry
about the copper atom in 1 is distorted square planar, with O1–Cu1–N1, N1–Cu1–N2 and O1–Cu1–O2 angles of 93.5(3)°,
157.6(3)°, and 154.4(3)° respectively. The Cu–N (amine) distance in 1 is quite similar to other reported Cu–N distances in the
1.995(6)-2.004(7) Å range, as in bis-{(diphenylmethyl)[(2-oxo-1H-benzo-1-yl-idene)-methyl]aminato}copper(II) and
604

Fig. 2. Packing structure of the complex along the c axis, showing the formation of a column by weak
intermolecular Br…Br interactions and Cu…Cl interactions.
bis-{(diphen-ylmethyl)[(2-oxo-1H-naphth-1-ylidene)-methyl]-aminato}copper(II) [9]. The Cu–O distances are 1.886 Å and
1.894 Å, which are also consistent with the corresponding Cu–O distance in bis(N-i-propyl-salicylidenaminato)copper(II)
[10] and bis(N-i-Pr-1,2-naphthaldiminato)copper(II) [11]. In the ligands, the lengths of N=C bonds are different on average
by 0.005 Å; the lengths of N–C bonds are different on average by 0.02 Å, while the C–C bonds of the phenyl rings are
different by 0.10 Å . The phenyl rings A and C of the ligands are nearly coplanar with the chelating rings. This is probably a
result of the coordination of N and O atoms to copper(II). To avoid steric conflicts, the phenyl rings B and D of the ligands,
are rotated with respect to the corresponding chelating rings with the dihedral angles of 51.7° and 50.1°.
Weak intermolecular Br…Br contracts are 3.521 Å; they connect the molecules to form a one-dimensional chain.
The complexes are packed into layers perpendicular to the c axis, where they are linked by Cu…Cl intermolecular contacts of
3.843 Å (Fig. 2).
The authors are grateful to the support of the Phytochemistry Key Laboratory of Shaanxi Province for the research
grant (No. 11JS008) and Baoji University of Arts and Sciences for the school-level key scientific research projects grant
(No. ZK11147) of China.
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