N4,N4′-Bis(4-meth­oxy­benzyl­idene)-3,3′-dimethyl­benzidine

Wang, J.; Yang, P.; Yang, J.

doi:10.1107/S1600536811023749

organic compounds

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ISSN: 2056-9890

Volume 67| Part 7| July 2011| Page o1753

doi:10.1107/S1600536811023749

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N⁴,N^4′-Bis(4-methoxybenzylidene)-3,3′-dimethylbenzidine

Juangang Wang,^a ^* Peipei Yang ^a and Jin Yang ^a

^aCollege of Chemistry and Material Science, Huaibei Normal University, Xiangshan, Huaibei 235000, People's Republic of China
^*Correspondence e-mail: 363019204@qq.com

(Received 16 June 2011; accepted 17 June 2011; online 22 June 2011)

The molecule of the title compund, C₃₀H₂₈N₂O₂, a Schiff base synthesised via a condensation reaction between 4-methoxybenzaldehyde and 3,3′-dimethylbenzidine, a crystallographic twofold rotation axis passes through the mid-point of the C—C bond of the biphenyl unit. Thus, the asymmetric unit comprises one half-molecule. In the biphenyl unit, the aromatic rings are twisted by 13.49 (7)° with respect to one another. The dihedral angles between the biphenyl and methoxybenzene rings are 49.95 (12) and 50.06 (12)°. In the crystal, weak intermolecular C—H⋯ O hydrogen bonds contribute to the stabilization of the packing.

Related literature

For the biological properties of Schiff base ligands, see: Bedia et al. (2006 ). For related structures, see: Harada et al. (2004 ); Nesterov (2004 ). For reference bond-length values, see: Allen et al. (1987 ).

Experimental

Crystal data

C₃₀H₂₈N₂O₂
M_r = 448.54
Monoclinic, C 2/c
a = 11.644 (2) Å
b = 16.228 (3) Å
c = 12.431 (3) Å
β = 91.75 (3)°
V = 2347.9 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 93 K
0.38 × 0.34 × 0.22 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ) T_min = 0.703, T_max = 0.786
11279 measured reflections
2667 independent reflections
2350 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.039
wR(F²) = 0.111
S = 1.05
2667 reflections
210 parameters
All H-atom parameters refined
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6A⋯O1ⁱ	0.960 (13)	2.688 (13)	3.4462 (15)	136.32 (su?)
Symmetry code: (i) $[x, -y, z-{\script{1\over 2}}]$ .

Data collection: RAPID-AUTO (Rigaku, 1998 ); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811023749/kp2337sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811023749/kp2337Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811023749/kp2337Isup3.cml

checkCIF report

Comment top

Schiff base ligands have received considerable attention during the last decades, mainly because of their structures or their biological properties (Bedia et al., 2006). We report here the crystal structure of the title compound, (I), a novel Schiff base (Fig. 1). The bond lengths (Allen et al., 1987) and angles are normal and comparable to the values observed in similar compounds (Harada et al., 2004; Nesterov et al., 2004). In the biphenyl moiety, the aromatic rings are inclined by 13.49 (7)°. The dihedral angles between the biphenyl and methoxybenzal rings are 49.95 (12)° and 50.06 (12)°, respectively. In the crystal, weak intermolecular C—H··· O hydrogen bonds contribute to the stabilisation of the packing (Table 1).

Related literature top

For the biological properties of Schiff base ligands, see: Bedia et al. (2006). For related structures, see: Harada et al. (2004); Nesterov et al. (2004). For reference bond-length values, see: Allen et al. (1987).

Experimental top

4-Methoxybenzaldehyde (0.272 g,2 mmol), 3,3'-Dimethylbenzidine (0.212 g,1 mmol) and 20 mL toluene were placed in a round-bottom flask equipped with a magnetic stirring bar. The reaction mixture was stirred at reflux for 4 h and then cooled.The solid that precipitated was filtered off and washed with methanol. This compound (0.224 g, 0.5 mmol) was dissolved in ethylacetate and left to crystallise. Crystals obtained were suitable for data collection.

Computing details top

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of the title compound, drawn with 30% probability displacement ellipsoids. The molecule has the crystallographic twofold rotation axes through the mid of C12-C12A. To generate the whole molecule symmetry operation A: -x,y, 1/2-z was used.

N⁴,N^4'-Bis(4-methoxybenzylidene)-3,3'-dimethylbenzidine top

Crystal data top

C₃₀H₂₈N₂O₂	F(000) = 952
M_r = 448.54	D_x = 1.269 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 9010 reflections
a = 11.644 (2) Å	θ = 3.0–27.5°
b = 16.228 (3) Å	µ = 0.08 mm⁻¹
c = 12.431 (3) Å	T = 93 K
β = 91.75 (3)°	Block, yellow
V = 2347.9 (8) Å³	0.38 × 0.34 × 0.22 mm
Z = 4

Data collection top

Rigaku R-AXIS RAPID diffractometer	2667 independent reflections
Radiation source: fine-focus sealed tube	2350 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.033
ω scans	θ_max = 27.5°, θ_min = 3.0°
Absorption correction: multi-scan (ABSCOR ;Higashi, 1995)	h = −15→15
T_min = 0.703, T_max = 0.786	k = −20→20
11279 measured reflections	l = −14→16

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.111	All H-atom parameters refined
S = 1.05	w = 1/[σ²(F_o²) + (0.0658P)² + 1.0766P] where P = (F_o² + 2F_c²)/3
2667 reflections	(Δ/σ)_max = 0.001
210 parameters	Δρ_max = 0.40 e Å⁻³
0 restraints	Δρ_min = −0.19 e Å⁻³

Crystal data top

C₃₀H₂₈N₂O₂	V = 2347.9 (8) Å³
M_r = 448.54	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 11.644 (2) Å	µ = 0.08 mm⁻¹
b = 16.228 (3) Å	T = 93 K
c = 12.431 (3) Å	0.38 × 0.34 × 0.22 mm
β = 91.75 (3)°

Data collection top

Rigaku R-AXIS RAPID diffractometer	2667 independent reflections
Absorption correction: multi-scan (ABSCOR ;Higashi, 1995)	2350 reflections with I > 2σ(I)
T_min = 0.703, T_max = 0.786	R_int = 0.033
11279 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.039	0 restraints
wR(F²) = 0.111	All H-atom parameters refined
S = 1.05	Δρ_max = 0.40 e Å⁻³
2667 reflections	Δρ_min = −0.19 e Å⁻³
210 parameters

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

	x	y	z	U_iso*/U_eq
O1	0.14801 (6)	0.07986 (5)	1.08572 (5)	0.01981 (19)
N1	0.36979 (7)	0.15477 (5)	0.62842 (7)	0.0176 (2)
C1	0.20415 (11)	0.12644 (8)	1.16991 (9)	0.0262 (3)
H1A	0.2839 (14)	0.1056 (10)	1.1839 (12)	0.034 (4)*
H1C	0.2050 (14)	0.1847 (10)	1.1522 (12)	0.038 (4)*
H1B	0.1570 (13)	0.1177 (10)	1.2330 (12)	0.037 (4)*
C2	0.18777 (9)	0.08948 (6)	0.98408 (8)	0.0165 (2)
C3	0.28693 (9)	0.13363 (6)	0.96025 (8)	0.0183 (2)
H3A	0.3342 (12)	0.1589 (8)	1.0165 (11)	0.025 (3)*
C4	0.31999 (9)	0.13940 (6)	0.85410 (8)	0.0179 (2)
H4A	0.3903 (12)	0.1681 (8)	0.8377 (10)	0.022 (3)*
C5	0.25488 (8)	0.10280 (6)	0.77062 (8)	0.0163 (2)
C6	0.15643 (9)	0.05837 (6)	0.79627 (8)	0.0179 (2)
H6A	0.1119 (11)	0.0334 (8)	0.7388 (10)	0.021 (3)*
C7	0.12313 (9)	0.05104 (6)	0.90185 (8)	0.0179 (2)
H7A	0.0561 (12)	0.0194 (8)	0.9196 (10)	0.024 (3)*
C8	0.28718 (8)	0.10911 (6)	0.65788 (8)	0.0176 (2)
H8A	0.2396 (11)	0.0762 (8)	0.6043 (10)	0.020 (3)*
C9	0.40025 (8)	0.15379 (6)	0.51899 (8)	0.0162 (2)
C10	0.43005 (8)	0.22903 (6)	0.47132 (8)	0.0159 (2)
C11	0.46879 (8)	0.22851 (6)	0.36602 (8)	0.0165 (2)
H11A	0.4919 (11)	0.2820 (9)	0.3346 (10)	0.023 (3)*
C12	0.47841 (8)	0.15556 (6)	0.30593 (7)	0.0160 (2)
C13	0.44641 (9)	0.08169 (6)	0.35559 (8)	0.0180 (2)
H13A	0.4501 (11)	0.0292 (8)	0.3175 (10)	0.019 (3)*
C14	0.40833 (9)	0.08084 (6)	0.46040 (8)	0.0183 (2)
H14A	0.3897 (12)	0.0279 (8)	0.4927 (10)	0.024 (3)*
C15	0.41802 (9)	0.30788 (7)	0.53365 (8)	0.0199 (2)
H15C	0.3378 (12)	0.3186 (9)	0.5538 (11)	0.028 (3)*
H15B	0.4624 (13)	0.3043 (9)	0.6036 (12)	0.032 (4)*
H15A	0.4450 (12)	0.3550 (8)	0.4925 (11)	0.025 (3)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0209 (4)	0.0261 (4)	0.0126 (4)	−0.0009 (3)	0.0023 (3)	0.0020 (3)
N1	0.0179 (4)	0.0209 (4)	0.0141 (4)	0.0005 (3)	0.0020 (3)	0.0021 (3)
C1	0.0341 (6)	0.0295 (6)	0.0151 (5)	−0.0047 (5)	0.0020 (4)	−0.0012 (4)
C2	0.0178 (5)	0.0179 (5)	0.0140 (5)	0.0039 (4)	0.0024 (3)	0.0029 (4)
C3	0.0184 (5)	0.0198 (5)	0.0166 (5)	−0.0003 (4)	−0.0011 (4)	0.0006 (4)
C4	0.0163 (5)	0.0192 (5)	0.0181 (5)	−0.0012 (4)	0.0012 (4)	0.0023 (4)
C5	0.0166 (5)	0.0171 (5)	0.0153 (5)	0.0021 (4)	0.0018 (3)	0.0019 (4)
C6	0.0171 (5)	0.0201 (5)	0.0166 (5)	−0.0001 (4)	0.0005 (4)	−0.0009 (4)
C7	0.0160 (5)	0.0195 (5)	0.0185 (5)	−0.0010 (4)	0.0032 (4)	0.0010 (4)
C8	0.0168 (5)	0.0200 (5)	0.0160 (5)	0.0009 (4)	0.0003 (4)	0.0014 (4)
C9	0.0130 (4)	0.0224 (5)	0.0132 (5)	−0.0003 (4)	0.0003 (3)	0.0011 (4)
C10	0.0129 (4)	0.0197 (5)	0.0150 (5)	−0.0008 (3)	0.0000 (3)	−0.0005 (4)
C11	0.0161 (5)	0.0184 (5)	0.0152 (5)	−0.0007 (4)	0.0008 (3)	0.0015 (4)
C12	0.0151 (5)	0.0191 (5)	0.0138 (5)	0.0002 (3)	0.0003 (4)	0.0004 (4)
C13	0.0195 (5)	0.0179 (5)	0.0167 (5)	−0.0003 (4)	0.0009 (4)	−0.0012 (4)
C14	0.0186 (5)	0.0187 (5)	0.0176 (5)	−0.0014 (4)	0.0016 (4)	0.0032 (4)
C15	0.0223 (5)	0.0203 (5)	0.0172 (5)	−0.0017 (4)	0.0040 (4)	−0.0021 (4)

Geometric parameters (Å, º) top

O1—C2	1.3677 (12)	C7—H7A	0.965 (14)
O1—C1	1.4325 (14)	C8—H8A	1.006 (13)
N1—C8	1.2767 (13)	C9—C14	1.3946 (15)
N1—C9	1.4164 (12)	C9—C10	1.4054 (14)
C1—H1A	0.999 (16)	C10—C11	1.3976 (14)
C1—H1C	0.972 (17)	C10—C15	1.5046 (14)
C1—H1B	0.981 (15)	C11—C12	1.4061 (14)
C2—C7	1.3978 (15)	C11—H11A	0.992 (14)
C2—C3	1.3982 (14)	C12—C13	1.4039 (14)
C3—C4	1.3891 (14)	C12—C12ⁱ	1.4930 (18)
C3—H3A	0.968 (14)	C13—C14	1.3892 (14)
C4—C5	1.3987 (15)	C13—H13A	0.975 (13)
C4—H4A	0.969 (14)	C14—H14A	0.976 (13)
C5—C6	1.3993 (14)	C15—H15C	0.990 (14)
C5—C8	1.4657 (13)	C15—H15B	1.000 (15)
C6—C7	1.3851 (14)	C15—H15A	0.977 (14)
C6—H6A	0.960 (13)

C2—O1—C1	117.07 (8)	N1—C8—H8A	121.5 (7)
C8—N1—C9	118.82 (9)	C5—C8—H8A	116.3 (7)
O1—C1—H1A	110.5 (9)	C14—C9—C10	119.73 (9)
O1—C1—H1C	110.8 (9)	C14—C9—N1	122.27 (9)
H1A—C1—H1C	110.7 (13)	C10—C9—N1	117.87 (9)
O1—C1—H1B	104.7 (9)	C11—C10—C9	118.72 (9)
H1A—C1—H1B	110.6 (12)	C11—C10—C15	121.69 (9)
H1C—C1—H1B	109.4 (13)	C9—C10—C15	119.58 (9)
O1—C2—C7	115.77 (9)	C10—C11—C12	122.41 (9)
O1—C2—C3	124.00 (9)	C10—C11—H11A	117.6 (7)
C7—C2—C3	120.23 (9)	C12—C11—H11A	120.0 (7)
C4—C3—C2	119.37 (10)	C13—C12—C11	117.30 (9)
C4—C3—H3A	119.3 (8)	C13—C12—C12ⁱ	120.73 (6)
C2—C3—H3A	121.3 (8)	C11—C12—C12ⁱ	121.96 (6)
C3—C4—C5	121.10 (9)	C14—C13—C12	121.17 (9)
C3—C4—H4A	119.5 (8)	C14—C13—H13A	117.8 (7)
C5—C4—H4A	119.4 (8)	C12—C13—H13A	121.1 (7)
C4—C5—C6	118.62 (9)	C13—C14—C9	120.66 (9)
C4—C5—C8	122.06 (9)	C13—C14—H14A	118.4 (7)
C6—C5—C8	119.33 (9)	C9—C14—H14A	120.9 (7)
C7—C6—C5	121.02 (10)	C10—C15—H15C	112.6 (8)
C7—C6—H6A	120.6 (8)	C10—C15—H15B	110.1 (9)
C5—C6—H6A	118.4 (8)	H15C—C15—H15B	104.9 (11)
C6—C7—C2	119.64 (9)	C10—C15—H15A	111.0 (8)
C6—C7—H7A	120.9 (8)	H15C—C15—H15A	108.4 (11)
C2—C7—H7A	119.4 (8)	H15B—C15—H15A	109.6 (12)
N1—C8—C5	122.17 (9)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6A···O1ⁱⁱ	0.960 (13)	2.688 (13)	3.4462 (15)	136.32

Symmetry code: (ii) x, −y, z−1/2.

Experimental details

Crystal data
Chemical formula	C₃₀H₂₈N₂O₂
M_r	448.54
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	93
a, b, c (Å)	11.644 (2), 16.228 (3), 12.431 (3)
β (°)	91.75 (3)
V (Å³)	2347.9 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.38 × 0.34 × 0.22

Data collection
Diffractometer	Rigaku R-AXIS RAPID diffractometer
Absorption correction	Multi-scan (ABSCOR ;Higashi, 1995)
T_min, T_max	0.703, 0.786
No. of measured, independent and observed [I > 2σ(I)] reflections	11279, 2667, 2350
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.039, 0.111, 1.05
No. of reflections	2667
No. of parameters	210
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.19

Computer programs: RAPID-AUTO (Rigaku, 1998), CrystalStructure (Rigaku/MSC, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6A···O1ⁱ	0.960 (13)	2.688 (13)	3.4462 (15)	136.32

Symmetry code: (i) x, −y, z−1/2.

Acknowledgements

Financial support from Huaibei Normal University is gratefully acknowledged.

References

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