supplementary materials


zs2261 scheme

Acta Cryst. (2013). E69, o1075    [ doi:10.1107/S1600536813014554 ]

rac-(E,E)-N,N'-Bis(2-chlorobenzylidene)cyclohexane-1,2-diamine

I. Warad, M. Al-Noaimi, S. F. Haddad, Y. Al-Demeri and B. Hammouti

Abstract top

In the title racemic Schiff base ligand, C20H20Cl2N2, which was prepared by the condensation of 2-chlorobenzaldehyde and cyclohexane-1,2-diamine, the cyclohexane ring adopts a chair conformation and the dihedral angle between the aromatic rings of the 2-chlorophenyl substituent groups is 62.52 (8)°. In the structure, there are two short intramolecular methine C-H...Cl interactions [C...Cl = 3.066 (2) and 3.076 (3) Å], and in the crystal there are also weak intermolecular aromatic C-H...Cl [3.464 (3), 3.553 (3) and 3.600 (3) Å] and Cl...Cl [3.557 (3) and 3.891 (3) Å] contacts.

Comment top

The chelating chiral Schiff bases are significant compounds in chemistry so that several reviews have been published on these substances (Gupta & Sutar, 2008; Da Silva et al., 2011; Przybylski et al., 2009). Because of their stereochemical features, as well as their industrial properties (Dhar & Taploo, 1982) and potent biological activities (Da Silva et al., 2011; Przybylski et al., 2009), they are very attractive synthetic targets. Furthermore, it should be stressed that these useful and recyclable chemicals have been widely used in various enantioselective reactions, such as cyclopropanation, aziridination, epoxidation or the Diels–Alder reaction, and as ligands or catalysts.

The title Schiff base, C20H20Cl2N2, was prepared by condensation of commercially available 2-chlorobenzaldehyde and (1R,2R)-diaminocyclohexane and the structure is reported herein. However, this compound is racemic, in which the cyclohexane ring adopts the expected chair conformation, with a dihedral angle of 62.52 (8)° between the aromatic rings of the two 2-chlorophenyl substituent groups (Fig. 1). The structure of the chiral isomeric (1R,2R) 4-chlorophenyl analogue has been reported (Arvinnezhad et al., 2012). In the title compound, the conformation is stabilized by intramolecular C7—H···Cl1 and C14—H··· Cl2 interactions [3.066 (2) and 3.076 (3) Å, respectively] (Table 1). In the crystal there are weak intermolecular methine C—H···Cl interactions [C10—H···Cl1 [3.600 (3) Å] (-x + 2, -y, -z), C11—H···Cl1 [3.553 (3) Å] (x - 1, y, z) and C20—H···Cl2 [3.464 (3) Å] (1 + x + 1, y, z). Also present in the crystal are Cl···Cl contacts [Cl1···Cl1, 3.557 (3) Å (-x + 1, -y, -z)] and 3.891 (3) Å (-x + 2, -y, -z) (Fig. 2).

Related literature top

For the crystal structures of some Schiff bases derived from cyclohexane-1,2-diamine, see: Arvinnezhad et al. (2012); Fan et al. (2011); Saleh Salga et al. (2010). For applications of chiral Schiff base ligands, see: Da Silva et al. (2011); Dhar & Taploo (1982); Przybylski et al. (2009); Gupta & Sutar (2008). For the synthesis of the title compound, see: Larrow & Jacobsen (1998).

Experimental top

(R,R)-1,2-Diaminocyclohexane (1 g, 8.9 mmol) was dissolved in EtOH (10 ml) and the mixture was stirred and heated gently (50 °C) for 10 min, after which a solution of 2-chlorobenzaldehyde (2.6 g, 18 mmol, 2 equivalents) in EtOH (5 ml) was added dropwise. The stirred reaction mixture was refluxed for a period of 4 h, with the reaction progress monitored by thin-layer chromatography. Upon completion of the reaction, the mixture was cooled to room temperature and the solid obtained was filtered off, washed with cold water and crystallized from ethanol (95%), with a 85% yield.

Refinement top

H atoms were positioned geometrically with C—H = 0.93 Å (aromatic), 0.97 Å (methylene) or 0.98 Å (methine) and allowed to ride in the refinement, with Uiso(H) = 1.2Ueq(C). The largest difference peak and hole are 0.276 and -0.204 e Å-3.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular conformation and atom-numbering scheme for the title compound. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.
[Figure 2] Fig. 2. Molecular conformation showing intramolecular C7—H···Cl1, C10—H···Cl1, C14—H···Cl2 and C17—H···Cl2 contacts, as well as a short intermolecular Cl1···Cl1A contact. For symmetry code (A): -x + 1, -y, -z.
rac-(E,E)-N,N'-Bis(2-chlorobenzylidene)cyclohexane-1,2-diamine top
Crystal data top
C20H20Cl2N2F(000) = 752
Mr = 359.28Dx = 1.281 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 2442 reflections
a = 5.9029 (5) Åθ = 3.1–29.1°
b = 19.5613 (13) ŵ = 0.35 mm1
c = 16.1662 (11) ÅT = 293 K
β = 93.493 (7)°Block, colourless
V = 1863.2 (2) Å30.30 × 0.20 × 0.15 mm
Z = 4
Data collection top
Agilent Xcalibur Eos
diffractometer
3273 independent reflections
Radiation source: Enhance (Mo) X-ray Source2252 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
Detector resolution: 16.0534 pixels mm-1θmax = 25.0°, θmin = 3.3°
ω scansh = 76
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
k = 2318
Tmin = 0.902, Tmax = 0.949l = 1917
7483 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.046Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.106H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.0349P)2 + 0.4202P]
where P = (Fo2 + 2Fc2)/3
3273 reflections(Δ/σ)max < 0.001
217 parametersΔρmax = 0.28 e Å3
0 restraintsΔρmin = 0.20 e Å3
Crystal data top
C20H20Cl2N2V = 1863.2 (2) Å3
Mr = 359.28Z = 4
Monoclinic, P21/nMo Kα radiation
a = 5.9029 (5) ŵ = 0.35 mm1
b = 19.5613 (13) ÅT = 293 K
c = 16.1662 (11) Å0.30 × 0.20 × 0.15 mm
β = 93.493 (7)°
Data collection top
Agilent Xcalibur Eos
diffractometer
3273 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
2252 reflections with I > 2σ(I)
Tmin = 0.902, Tmax = 0.949Rint = 0.030
7483 measured reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.106Δρmax = 0.28 e Å3
S = 1.02Δρmin = 0.20 e Å3
3273 reflectionsAbsolute structure: ?
217 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.73684 (13)0.05324 (3)0.02770 (4)0.0762 (2)
Cl21.12436 (13)0.46542 (4)0.17646 (5)0.0914 (3)
N10.7836 (3)0.26396 (10)0.03727 (11)0.0555 (5)
C80.9564 (4)0.17516 (12)0.04725 (12)0.0489 (6)
C10.5739 (4)0.29405 (11)0.07382 (12)0.0520 (6)
H1B0.44420.26740.05670.062*
C60.5559 (4)0.36693 (12)0.04157 (13)0.0583 (7)
H6A0.68850.39320.05680.070*
N20.5510 (4)0.36480 (10)0.04896 (11)0.0613 (6)
C140.7170 (5)0.39062 (12)0.09007 (14)0.0586 (6)
H14A0.83180.41100.06170.070*
C70.7660 (4)0.20790 (12)0.00033 (12)0.0492 (6)
H7A0.62580.18610.00320.059*
C131.1395 (4)0.21396 (13)0.07903 (13)0.0587 (6)
H13A1.14650.26020.06610.070*
C150.7373 (4)0.38992 (12)0.18143 (14)0.0550 (6)
C101.1237 (5)0.07662 (14)0.11857 (14)0.0673 (8)
H10A1.11790.03040.13170.081*
C90.9546 (4)0.10611 (12)0.06799 (12)0.0540 (6)
C160.9153 (4)0.42153 (12)0.22641 (15)0.0615 (7)
C200.5769 (5)0.35715 (13)0.22604 (15)0.0669 (7)
H20A0.45460.33590.19760.080*
C111.3010 (5)0.11644 (17)0.14930 (15)0.0777 (9)
H11A1.41560.09720.18380.093*
C170.9323 (5)0.42009 (15)0.31214 (17)0.0756 (8)
H17A1.05350.44150.34110.091*
C20.5740 (4)0.29389 (13)0.16818 (13)0.0634 (7)
H2B0.70730.31780.18530.076*
H2C0.58040.24720.18800.076*
C30.3615 (5)0.32848 (13)0.20597 (14)0.0679 (7)
H3A0.36790.32980.26580.081*
H3B0.22920.30200.19310.081*
C50.3413 (5)0.40078 (14)0.07892 (15)0.0783 (9)
H5A0.33400.44760.05940.094*
H5B0.20930.37660.06100.094*
C121.3100 (4)0.18501 (17)0.12915 (15)0.0725 (8)
H12A1.43150.21160.14950.087*
C190.5930 (5)0.35511 (14)0.31149 (17)0.0783 (8)
H19A0.48410.33220.34010.094*
C40.3382 (5)0.40022 (14)0.17353 (16)0.0825 (9)
H4A0.19700.41990.19620.099*
H4B0.46200.42810.19150.099*
C180.7716 (6)0.38728 (15)0.35396 (17)0.0819 (9)
H18A0.78250.38660.41160.098*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0871 (5)0.0566 (4)0.0835 (5)0.0021 (4)0.0058 (4)0.0000 (3)
Cl20.0686 (5)0.1026 (6)0.1027 (6)0.0136 (4)0.0018 (4)0.0098 (4)
N10.0581 (13)0.0600 (13)0.0482 (11)0.0065 (10)0.0025 (10)0.0112 (9)
C80.0547 (15)0.0576 (15)0.0350 (11)0.0102 (12)0.0076 (10)0.0003 (10)
C10.0560 (15)0.0538 (14)0.0457 (12)0.0028 (12)0.0003 (11)0.0077 (10)
C60.0690 (17)0.0549 (15)0.0499 (13)0.0001 (13)0.0050 (12)0.0039 (11)
N20.0686 (14)0.0649 (13)0.0497 (11)0.0024 (11)0.0019 (10)0.0047 (9)
C140.0677 (17)0.0493 (14)0.0583 (15)0.0044 (13)0.0002 (13)0.0018 (11)
C70.0542 (14)0.0543 (14)0.0393 (11)0.0055 (12)0.0034 (10)0.0002 (11)
C130.0649 (17)0.0636 (16)0.0478 (13)0.0032 (13)0.0052 (12)0.0007 (11)
C150.0638 (16)0.0454 (14)0.0547 (14)0.0065 (12)0.0065 (13)0.0056 (11)
C100.087 (2)0.0641 (17)0.0496 (14)0.0270 (16)0.0021 (14)0.0012 (12)
C90.0653 (16)0.0589 (15)0.0376 (12)0.0145 (13)0.0024 (11)0.0025 (10)
C160.0647 (17)0.0533 (15)0.0656 (16)0.0062 (13)0.0041 (13)0.0067 (12)
C200.0782 (19)0.0636 (17)0.0576 (16)0.0079 (15)0.0060 (14)0.0053 (12)
C110.081 (2)0.097 (2)0.0536 (15)0.0358 (18)0.0137 (15)0.0084 (15)
C170.081 (2)0.076 (2)0.0680 (18)0.0003 (17)0.0157 (16)0.0181 (15)
C20.0752 (18)0.0686 (17)0.0461 (13)0.0056 (14)0.0021 (13)0.0066 (12)
C30.0817 (19)0.0721 (18)0.0481 (14)0.0024 (15)0.0103 (13)0.0079 (12)
C50.096 (2)0.0648 (17)0.0712 (18)0.0260 (16)0.0146 (16)0.0042 (14)
C120.0621 (17)0.098 (2)0.0570 (16)0.0101 (17)0.0040 (14)0.0143 (15)
C190.095 (2)0.0727 (19)0.0674 (18)0.0071 (17)0.0074 (16)0.0016 (14)
C40.100 (2)0.0716 (19)0.0717 (18)0.0166 (17)0.0243 (17)0.0146 (14)
C180.111 (3)0.077 (2)0.0552 (16)0.0005 (19)0.0075 (18)0.0097 (14)
Geometric parameters (Å, º) top
Cl1—C91.745 (2)C10—H10A0.9300
Cl2—C161.742 (3)C16—C171.384 (3)
N1—C71.256 (3)C20—C191.379 (3)
N1—C11.462 (3)C20—H20A0.9300
C8—C91.392 (3)C11—C121.382 (4)
C8—C131.393 (3)C11—H11A0.9300
C8—C71.469 (3)C17—C181.359 (4)
C1—C61.524 (3)C17—H17A0.9300
C1—C21.525 (3)C2—C31.520 (3)
C1—H1B0.9800C2—H2B0.9700
C6—N21.466 (3)C2—H2C0.9700
C6—C51.522 (3)C3—C41.507 (4)
C6—H6A0.9800C3—H3A0.9700
N2—C141.256 (3)C3—H3B0.9700
C14—C151.475 (3)C5—C41.529 (3)
C14—H14A0.9300C5—H5A0.9700
C7—H7A0.9300C5—H5B0.9700
C13—C121.375 (3)C12—H12A0.9300
C13—H13A0.9300C19—C181.375 (4)
C15—C201.383 (3)C19—H19A0.9300
C15—C161.386 (3)C4—H4A0.9700
C10—C111.373 (4)C4—H4B0.9700
C10—C91.378 (3)C18—H18A0.9300
C7—N1—C1116.8 (2)C15—C20—H20A119.1
C9—C8—C13117.2 (2)C10—C11—C12120.3 (2)
C9—C8—C7122.2 (2)C10—C11—H11A119.9
C13—C8—C7120.5 (2)C12—C11—H11A119.9
N1—C1—C6108.26 (18)C18—C17—C16119.8 (3)
N1—C1—C2110.58 (19)C18—C17—H17A120.1
C6—C1—C2110.38 (18)C16—C17—H17A120.1
N1—C1—H1B109.2C3—C2—C1110.5 (2)
C6—C1—H1B109.2C3—C2—H2B109.5
C2—C1—H1B109.2C1—C2—H2B109.5
N2—C6—C5110.0 (2)C3—C2—H2C109.5
N2—C6—C1108.72 (18)C1—C2—H2C109.5
C5—C6—C1110.19 (19)H2B—C2—H2C108.1
N2—C6—H6A109.3C4—C3—C2111.4 (2)
C5—C6—H6A109.3C4—C3—H3A109.3
C1—C6—H6A109.3C2—C3—H3A109.3
C14—N2—C6117.0 (2)C4—C3—H3B109.3
N2—C14—C15122.6 (3)C2—C3—H3B109.3
N2—C14—H14A118.7H3A—C3—H3B108.0
C15—C14—H14A118.7C6—C5—C4110.7 (2)
N1—C7—C8123.1 (2)C6—C5—H5A109.5
N1—C7—H7A118.4C4—C5—H5A109.5
C8—C7—H7A118.4C6—C5—H5B109.5
C12—C13—C8121.1 (3)C4—C5—H5B109.5
C12—C13—H13A119.5H5A—C5—H5B108.1
C8—C13—H13A119.5C13—C12—C11120.1 (3)
C20—C15—C16117.0 (2)C13—C12—H12A119.9
C20—C15—C14120.7 (2)C11—C12—H12A119.9
C16—C15—C14122.3 (3)C18—C19—C20119.4 (3)
C11—C10—C9119.1 (3)C18—C19—H19A120.3
C11—C10—H10A120.5C20—C19—H19A120.3
C9—C10—H10A120.5C3—C4—C5111.0 (2)
C10—C9—C8122.2 (2)C3—C4—H4A109.4
C10—C9—Cl1117.6 (2)C5—C4—H4A109.4
C8—C9—Cl1120.09 (17)C3—C4—H4B109.4
C17—C16—C15121.5 (3)C5—C4—H4B109.4
C17—C16—Cl2117.6 (2)H4A—C4—H4B108.0
C15—C16—Cl2120.8 (2)C17—C18—C19120.3 (3)
C19—C20—C15121.9 (2)C17—C18—H18A119.8
C19—C20—H20A119.1C19—C18—H18A119.8
C7—N1—C1—C6126.4 (2)C20—C15—C16—C170.3 (4)
C7—N1—C1—C2112.5 (2)C14—C15—C16—C17179.7 (2)
N1—C1—C6—N260.1 (3)C20—C15—C16—Cl2178.99 (19)
C2—C1—C6—N2178.69 (19)C14—C15—C16—Cl21.0 (3)
N1—C1—C6—C5179.2 (2)C16—C15—C20—C190.7 (4)
C2—C1—C6—C558.1 (3)C14—C15—C20—C19179.3 (2)
C5—C6—N2—C14125.3 (2)C9—C10—C11—C120.5 (4)
C1—C6—N2—C14114.0 (2)C15—C16—C17—C180.2 (4)
C6—N2—C14—C15178.0 (2)Cl2—C16—C17—C18179.1 (2)
C1—N1—C7—C8173.03 (19)N1—C1—C2—C3177.1 (2)
C9—C8—C7—N1161.7 (2)C6—C1—C2—C357.3 (3)
C13—C8—C7—N123.4 (3)C1—C2—C3—C456.3 (3)
C9—C8—C13—C120.4 (3)N2—C6—C5—C4177.2 (2)
C7—C8—C13—C12174.8 (2)C1—C6—C5—C457.3 (3)
N2—C14—C15—C203.3 (4)C8—C13—C12—C110.4 (4)
N2—C14—C15—C16176.7 (2)C10—C11—C12—C130.9 (4)
C11—C10—C9—C80.4 (4)C15—C20—C19—C180.9 (4)
C11—C10—C9—Cl1178.1 (2)C2—C3—C4—C555.8 (3)
C13—C8—C9—C100.8 (3)C6—C5—C4—C356.3 (3)
C7—C8—C9—C10174.3 (2)C16—C17—C18—C190.5 (4)
C13—C8—C9—Cl1177.66 (17)C20—C19—C18—C170.8 (4)
C7—C8—C9—Cl17.3 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C7—H7A···Cl10.932.723.066 (2)103
C14—H14A···Cl20.932.683.076 (3)107

Experimental details

Crystal data
Chemical formulaC20H20Cl2N2
Mr359.28
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)5.9029 (5), 19.5613 (13), 16.1662 (11)
β (°) 93.493 (7)
V3)1863.2 (2)
Z4
Radiation typeMo Kα
µ (mm1)0.35
Crystal size (mm)0.30 × 0.20 × 0.15
Data collection
DiffractometerAgilent Xcalibur Eos
diffractometer
Absorption correctionMulti-scan
(CrysAlis PRO; Agilent, 2011)
Tmin, Tmax0.902, 0.949
No. of measured, independent and
observed [I > 2σ(I)] reflections
7483, 3273, 2252
Rint0.030
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.106, 1.02
No. of reflections3273
No. of parameters217
No. of restraints0
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.28, 0.20

Computer programs: CrysAlis PRO (Agilent, 2011), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996).

Acknowledgements top

This project was supported by An-Najah National University and Hashemite University. The X-ray structural work was carried out at the Hamdi Mango Center for Scientific Research at the University of Jordan.

references
References top

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