Crystal structure of N¹,N¹-diethyl-N⁴-[(quinolin-2-yl)methyl­idene]benzene-1,4-di­amine

The title compound, C₂₀H₂₁N₃, is non-planar with a dihedral angle between the planes of the quinoline and phenyl­enedi­amine rings of 9.40 (4)°. In the crystal, mol­ecules are connected by C—H...π inter­actions, generating a chain extending along the a-axis direction. Weak C—H...π inter­actions also occur.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.084
• wR factor = 0.195
• Data-to-parameter ratio = 13.9

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.12
            Rint given   0.146
PLAT020_ALERT_3_C The value of Rint is greater than 0.12 .........      0.146 Report
PLAT147_ALERT_1_C su on Symmetry Constrained Cell Angle(s) .......     Please Check
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0050 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1 Note
              C20 H21 N3
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......     22.120 Check
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      3.464 Check
PLAT934_ALERT_3_C Number of (Iobs-Icalc)/SigmaW > 10 Outliers ....          1 Check

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT066_ALERT_1_G Predicted and Reported Tmin&Tmax Range Identical          ? Check
PLAT153_ALERT_1_G The su's on the Cell Axes   are Equal ..........    0.00500 Ang.
PLAT899_ALERT_4_G SHELXL97   is Deprecated and Succeeded by SHELXL       2014 Note
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          39 %

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   8 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   7 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Quinoline derivatives of Schiff bases are important building blocks of many important compounds widely used in biological applications such as antioxidative and anticancer and fluorescent probe agents in industry and in coordination chemistry (Motswainyana et al., 2013; Das et al., 2013; Song et al., 2011; Jursic et al., 2002). The present work is part of an ongoing structural study of Schiff base metal complexes (Faizi & Hussain, 2014; Faizi & Sen, 2014; Faizi et al. 2014) and we report here the structure of N¹,N¹-diethyl-N⁴-[(quinolin-2-yl)methylidene]benzene-1,4-diamine (DQMBD). There are very few examples similar to title compound and their metal complex have been reported in the literature (Patra & Goldberg 2003; Gonzalez et al., 2012). The synthesis of DQMBD by condensation of 2-quinolinecarboxaldehyde and N¹,N¹-diethyl-p-phenylenediamine has not previously been reported. In the title compound (Fig. 1) DQMBD has non planar structure, the dihedral angle between the quinolinyl and pphenylenediamine rings is 9.40 (4)°. In the crystal, molecules are connected by C—H···π, generating a chain extending along the a axis direction. In the crystal molecules are connected by C—H···π, giving an overall two-dimensional layered structure lying parallel to (100) is given in Fig. 2.

Related literature

For applications of quinolinyl-containing Schiff bases, see: Das et al. (2013); Jursic et al. (2002); Motswainyana et al. (2013); Song et al. (2011). The present work is part of an ongoing structural study of Schiff base–metal complexes, see: Faizi & Hussain (2014); Faizi & Sen (2014); Faizi et al. (2014). For related Schiff bases and their applications, see: Gonzalez et al. (2012); Patra & Goldberg (2003).

S2. Experimental

100 mg (1 mmol) of N¹,N¹-diethyl-p-phenylenediamine were dissolved in 10 ml of absolute ethanol. To this solution, 96 mg (1 mmol) of 2-quinolinecarboxaldehyde in 5 ml of absolute ethanol was dropwisely added under stirring. Then, this mixture was stirred for 10 min, two drops of glacial acetic acid were then added and the mixture was further refluxed for 2h. The resulting yellow precipitate was recovered by filtration, washed several times with a small portions of EtOH and then with diethyl ether to give 160 mg (88%) of N¹,N¹-diethyl-N⁴-(quinolin-2-ylmethylene)benzene-1,4-diamine (DQMBD). The crystal of the title compound suitable for X-ray analysis was obtained within 4 days by slow evaporation of the EtOH solvent.

S3. Refinement

the N-bound H-atoms were located in difference Fourier maps,and their positions were then held fixed. All H-atoms were positioned geometrically and refined using a riding model with C—H = 0.92–0.93 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: DIAMOND (Brandenberg & Putz, 2005); software used to prepare material for publication: DIAMOND (Brandenberg & Putz, 2005).

Figures

	Fig. 1. The molecular conformation and atom-numbering scheme for the title compound, with non-H atoms drawn as 40% probability displacement ellipsoids.
	Fig. 2. The molecular packing viewed along the a direction.

N¹,N¹-Diethyl-N⁴-[(quinolin-2-yl)methylidene]benzene-1,4-diamine

Crystal data

C20H21N3	F(000) = 1296
Mr = 303.40	Dx = 1.206 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 1765 reflections
a = 20.354 (5) Å	θ = 2.7–27.5°
b = 7.534 (5) Å	µ = 0.07 mm^−1
c = 21.801 (5) Å	T = 100 K
V = 3343 (2) Å^3	Needle, yellow
Z = 8	0.27 × 0.21 × 0.16 mm

Data collection

Bruker SMART APEX CCD diffractometer	2937 independent reflections
Radiation source: fine-focus sealed tube	1912 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.146
/w–scans	θmax = 25.0°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	h = −24→23
Tmin = 0.981, Tmax = 0.989	k = −8→8
14928 measured reflections	l = −18→25

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.084	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.195	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0662P)^2 + 3.082P] where P = (Fo^2 + 2Fc^2)/3
2937 reflections	(Δ/σ)max < 0.001
212 parameters	Δρmax = 0.32 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.35623 (17)	−0.0493 (5)	0.07353 (16)	0.0221 (9)
C2	0.38904 (17)	−0.1200 (5)	0.12533 (16)	0.0243 (9)
H2	0.4301	−0.1726	0.1205	0.029*
C3	0.36114 (17)	−0.1119 (5)	0.18233 (16)	0.0241 (9)
H3	0.3830	−0.1600	0.2159	0.029*
C4	0.29920 (19)	−0.0306 (5)	0.19034 (17)	0.0292 (10)
H4	0.2806	−0.0249	0.2292	0.035*
C5	0.26640 (18)	0.0397 (5)	0.14123 (16)	0.0246 (9)
H5	0.2257	0.0930	0.1472	0.029*
C6	0.29346 (17)	0.0326 (4)	0.08169 (16)	0.0195 (8)
C7	0.26231 (17)	0.0998 (5)	0.02881 (16)	0.0233 (9)
H7	0.2216	0.1552	0.0322	0.028*
C8	0.29143 (17)	0.0843 (5)	−0.02734 (16)	0.0237 (9)
H8	0.2705	0.1256	−0.0625	0.028*
C9	0.35419 (17)	0.0040 (5)	−0.03101 (16)	0.0204 (8)
C10	0.38967 (19)	−0.0092 (5)	−0.08980 (17)	0.0232 (9)
C11	0.39650 (17)	0.0327 (5)	−0.19610 (15)	0.0208 (8)
C12	0.45481 (18)	−0.0590 (5)	−0.20748 (16)	0.0229 (8)
H12	0.4741	−0.1235	−0.1759	0.027*
C13	0.48440 (17)	−0.0565 (5)	−0.26392 (15)	0.0225 (9)
H13	0.5233	−0.1190	−0.2696	0.027*
C14	0.45734 (17)	0.0384 (5)	−0.31347 (15)	0.0197 (8)
C15	0.39852 (16)	0.1316 (5)	−0.30210 (16)	0.0208 (8)
H15	0.3792	0.1971	−0.3335	0.025*
C16	0.36925 (17)	0.1269 (5)	−0.24513 (15)	0.0199 (8)
H16	0.3301	0.1883	−0.2391	0.024*
C17	0.46058 (17)	0.1451 (5)	−0.42064 (15)	0.0226 (9)
H17A	0.4951	0.1662	−0.4505	0.027*
H17B	0.4464	0.2595	−0.4051	0.027*
C18	0.40284 (17)	0.0555 (5)	−0.45265 (16)	0.0255 (9)
H18A	0.3874	0.1299	−0.4854	0.038*
H18B	0.3680	0.0367	−0.4237	0.038*
H18C	0.4167	−0.0567	−0.4691	0.038*
C19	0.54187 (16)	−0.0777 (5)	−0.38531 (15)	0.0213 (8)
H19A	0.5381	−0.1130	−0.4280	0.026*
H19B	0.5382	−0.1839	−0.3604	0.026*
C20	0.60919 (18)	0.0044 (6)	−0.37512 (18)	0.0308 (10)
H20A	0.6426	−0.0802	−0.3856	0.046*
H20B	0.6137	0.0375	−0.3328	0.046*
H20C	0.6137	0.1078	−0.4005	0.046*
N1	0.38663 (14)	−0.0612 (4)	0.01724 (13)	0.0227 (8)
N2	0.36253 (14)	0.0420 (4)	−0.13964 (13)	0.0227 (7)
N3	0.48728 (14)	0.0418 (4)	−0.37025 (12)	0.0201 (7)
H10	0.4353 (17)	−0.053 (4)	−0.0845 (14)	0.015 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.021 (2)	0.020 (2)	0.025 (2)	−0.0063 (16)	0.0031 (16)	−0.0065 (16)
C2	0.019 (2)	0.024 (2)	0.030 (2)	−0.0016 (16)	0.0000 (16)	−0.0058 (17)
C3	0.025 (2)	0.028 (2)	0.0193 (19)	−0.0033 (17)	−0.0025 (16)	−0.0011 (16)
C4	0.030 (2)	0.033 (2)	0.025 (2)	−0.0110 (18)	0.0055 (17)	−0.0053 (18)
C5	0.020 (2)	0.027 (2)	0.027 (2)	−0.0042 (16)	0.0055 (16)	−0.0068 (17)
C6	0.0166 (19)	0.0157 (19)	0.0261 (19)	−0.0065 (15)	0.0018 (15)	−0.0037 (15)
C7	0.016 (2)	0.021 (2)	0.033 (2)	0.0013 (15)	0.0014 (16)	−0.0035 (17)
C8	0.023 (2)	0.023 (2)	0.025 (2)	−0.0025 (16)	−0.0044 (16)	−0.0014 (16)
C9	0.022 (2)	0.015 (2)	0.0239 (19)	−0.0012 (15)	−0.0022 (15)	−0.0019 (15)
C10	0.022 (2)	0.022 (2)	0.026 (2)	0.0014 (16)	0.0010 (16)	0.0003 (16)
C11	0.023 (2)	0.023 (2)	0.0170 (18)	−0.0011 (16)	0.0016 (15)	−0.0021 (15)
C12	0.026 (2)	0.021 (2)	0.0212 (19)	0.0028 (16)	−0.0063 (16)	0.0007 (16)
C13	0.019 (2)	0.025 (2)	0.023 (2)	0.0060 (16)	−0.0012 (15)	−0.0025 (16)
C14	0.020 (2)	0.020 (2)	0.0191 (18)	−0.0048 (15)	−0.0011 (15)	−0.0034 (15)
C15	0.0205 (19)	0.022 (2)	0.0196 (19)	0.0039 (16)	−0.0061 (15)	0.0010 (16)
C16	0.0134 (18)	0.024 (2)	0.0224 (19)	−0.0006 (15)	−0.0029 (15)	−0.0050 (16)
C17	0.022 (2)	0.025 (2)	0.0207 (19)	−0.0001 (16)	−0.0018 (15)	0.0002 (16)
C18	0.025 (2)	0.031 (2)	0.0203 (19)	0.0025 (17)	0.0002 (16)	0.0029 (16)
C19	0.019 (2)	0.027 (2)	0.0175 (19)	0.0035 (15)	0.0036 (15)	−0.0015 (16)
C20	0.026 (2)	0.034 (2)	0.032 (2)	0.0057 (18)	0.0025 (17)	0.0039 (19)
N1	0.0247 (18)	0.0214 (19)	0.0221 (17)	−0.0012 (13)	0.0046 (13)	−0.0022 (13)
N2	0.0211 (17)	0.0194 (17)	0.0277 (18)	−0.0012 (13)	−0.0012 (13)	−0.0017 (14)
N3	0.0177 (17)	0.0266 (18)	0.0161 (15)	0.0078 (13)	−0.0002 (12)	0.0001 (13)

Geometric parameters (Å, º)

C1—N1	1.377 (4)	C12—C13	1.370 (5)
C1—C2	1.416 (5)	C12—H12	0.9300
C1—C6	1.430 (5)	C13—C14	1.408 (5)
C2—C3	1.368 (5)	C13—H13	0.9300
C2—H2	0.9300	C14—N3	1.380 (4)
C3—C4	1.412 (5)	C14—C15	1.410 (5)
C3—H3	0.9300	C15—C16	1.378 (5)
C4—C5	1.368 (5)	C15—H15	0.9300
C4—H4	0.9300	C16—H16	0.9300
C5—C6	1.411 (5)	C17—N3	1.452 (4)
C5—H5	0.9300	C17—C18	1.525 (5)
C6—C7	1.410 (5)	C17—H17A	0.9700
C7—C8	1.365 (5)	C17—H17B	0.9700
C7—H7	0.9300	C18—H18A	0.9600
C8—C9	1.416 (5)	C18—H18B	0.9600
C8—H8	0.9300	C18—H18C	0.9600
C9—N1	1.336 (4)	C19—N3	1.467 (4)
C9—C10	1.474 (5)	C19—C20	1.519 (5)
C10—N2	1.278 (5)	C19—H19A	0.9700
C10—H10	0.99 (3)	C19—H19B	0.9700
C11—C12	1.396 (5)	C20—H20A	0.9600
C11—C16	1.398 (5)	C20—H20B	0.9600
C11—N2	1.413 (4)	C20—H20C	0.9600
N1—C1—C2	118.3 (3)	N3—C14—C13	121.7 (3)
N1—C1—C6	122.7 (3)	N3—C14—C15	121.6 (3)
C2—C1—C6	119.0 (3)	C13—C14—C15	116.8 (3)
C3—C2—C1	120.8 (3)	C16—C15—C14	120.8 (3)
C3—C2—H2	119.6	C16—C15—H15	119.6
C1—C2—H2	119.6	C14—C15—H15	119.6
C2—C3—C4	120.2 (3)	C15—C16—C11	122.1 (3)
C2—C3—H3	119.9	C15—C16—H16	119.0
C4—C3—H3	119.9	C11—C16—H16	119.0
C5—C4—C3	120.4 (3)	N3—C17—C18	113.4 (3)
C5—C4—H4	119.8	N3—C17—H17A	108.9
C3—C4—H4	119.8	C18—C17—H17A	108.9
C4—C5—C6	121.0 (4)	N3—C17—H17B	108.9
C4—C5—H5	119.5	C18—C17—H17B	108.9
C6—C5—H5	119.5	H17A—C17—H17B	107.7
C7—C6—C5	124.3 (3)	C17—C18—H18A	109.5
C7—C6—C1	117.1 (3)	C17—C18—H18B	109.5
C5—C6—C1	118.7 (3)	H18A—C18—H18B	109.5
C8—C7—C6	120.5 (3)	C17—C18—H18C	109.5
C8—C7—H7	119.8	H18A—C18—H18C	109.5
C6—C7—H7	119.8	H18B—C18—H18C	109.5
C7—C8—C9	118.6 (3)	N3—C19—C20	113.6 (3)
C7—C8—H8	120.7	N3—C19—H19A	108.8
C9—C8—H8	120.7	C20—C19—H19A	108.8
N1—C9—C8	124.0 (3)	N3—C19—H19B	108.8
N1—C9—C10	114.7 (3)	C20—C19—H19B	108.8
C8—C9—C10	121.3 (3)	H19A—C19—H19B	107.7
N2—C10—C9	120.5 (3)	C19—C20—H20A	109.5
N2—C10—H10	127.2 (18)	C19—C20—H20B	109.5
C9—C10—H10	112.2 (18)	H20A—C20—H20B	109.5
C12—C11—C16	116.9 (3)	C19—C20—H20C	109.5
C12—C11—N2	126.5 (3)	H20A—C20—H20C	109.5
C16—C11—N2	116.5 (3)	H20B—C20—H20C	109.5
C13—C12—C11	121.8 (3)	C9—N1—C1	117.1 (3)
C13—C12—H12	119.1	C10—N2—C11	120.9 (3)
C11—C12—H12	119.1	C14—N3—C17	121.6 (3)
C12—C13—C14	121.6 (3)	C14—N3—C19	121.6 (3)
C12—C13—H13	119.2	C17—N3—C19	116.3 (3)
C14—C13—H13	119.2
N1—C1—C2—C3	−180.0 (3)	C12—C13—C14—C15	0.4 (5)
C6—C1—C2—C3	0.5 (5)	N3—C14—C15—C16	−180.0 (3)
C1—C2—C3—C4	−0.7 (6)	C13—C14—C15—C16	−0.7 (5)
C2—C3—C4—C5	0.4 (6)	C14—C15—C16—C11	0.9 (5)
C3—C4—C5—C6	0.1 (6)	C12—C11—C16—C15	−0.7 (5)
C4—C5—C6—C7	179.1 (3)	N2—C11—C16—C15	178.5 (3)
C4—C5—C6—C1	−0.2 (5)	C8—C9—N1—C1	0.4 (5)
N1—C1—C6—C7	1.1 (5)	C10—C9—N1—C1	178.8 (3)
C2—C1—C6—C7	−179.5 (3)	C2—C1—N1—C9	179.0 (3)
N1—C1—C6—C5	−179.5 (3)	C6—C1—N1—C9	−1.6 (5)
C2—C1—C6—C5	−0.1 (5)	C9—C10—N2—C11	178.9 (3)
C5—C6—C7—C8	−178.7 (3)	C12—C11—N2—C10	13.1 (6)
C1—C6—C7—C8	0.6 (5)	C16—C11—N2—C10	−166.1 (3)
C6—C7—C8—C9	−1.8 (5)	C13—C14—N3—C17	−177.7 (3)
C7—C8—C9—N1	1.3 (5)	C15—C14—N3—C17	1.5 (5)
C7—C8—C9—C10	−177.1 (3)	C13—C14—N3—C19	11.2 (5)
N1—C9—C10—N2	177.1 (3)	C15—C14—N3—C19	−169.6 (3)
C8—C9—C10—N2	−4.5 (5)	C18—C17—N3—C14	−79.2 (4)
C16—C11—C12—C13	0.4 (5)	C18—C17—N3—C19	92.3 (4)
N2—C11—C12—C13	−178.8 (3)	C20—C19—N3—C14	−94.8 (4)
C11—C12—C13—C14	−0.2 (6)	C20—C19—N3—C17	93.7 (4)
C12—C13—C14—N3	179.6 (3)

Hydrogen-bond geometry (Å, º)

Cg1, Cg2 and Cg3 are the centroids of the N1/C1/C6–C9, C1–C16 and C11–C16 rings, respectively.

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···Cg2^i	0.93	2.99	3.705 (5)	135
C7—H7···Cg1^i	0.93	2.90	3.612 (5)	135
C13—H13···Cg3^ii	0.93	2.84	3.588 (5)	138
C15—H15···Cg2^iii	0.93	2.89	3.686 (5)	145
C18—H18A···Cg1^iii	0.96	2.95	3.625 (5)	128

Symmetry codes: (i) −x+1/2, y+1/2, z; (ii) −x+1, y−1/2, −z−1/2; (iii) x, −y+1/2, z−1/2.