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Acta Crystallogr Sect E Struct Rep Online. 2008 January 1; 64(Pt 1): o161.
Published online 2007 December 6. doi:  10.1107/S1600536807064768
PMCID: PMC2915229

4,4′-Dimethyl-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­idyne)]diphenol

Abstract

In the title Schiff base, C22H20N2O2, the benzene ring forms dihedral angles of 53.92 (1) and 3.62 (1)° with the two salicylaldimine groups. There are two strong O—H(...)N intra­molecular hydrogen bonds. The crystal packing is stabilized by weak inter­molecular C—H(...)O hydrogen bonds and π–π stacking inter­actions (average distance 3.39 Å).

Related literature

For related literature, see: Cohen et al. (1964 [triangle]).

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Object name is e-64-0o161-scheme1.jpg

Experimental

Crystal data

  • C22H20N2O2
  • M r = 344.40
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o161-efi1.jpg
  • a = 6.0835 (12) Å
  • b = 16.207 (3) Å
  • c = 18.607 (4) Å
  • β = 98.28 (3)°
  • V = 1815.4 (6) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 296 (2) K
  • 0.33 × 0.28 × 0.21 mm

Data collection

  • Rigaku R-AXIS RAPID diffractometer
  • Absorption correction: multi-scan (ABSCOR; Higashi, 1995 [triangle]) T min = 0.971, T max = 0.985
  • 17288 measured reflections
  • 4063 independent reflections
  • 2571 reflections with I > 2σ(I)
  • R int = 0.037

Refinement

  • R[F 2 > 2σ(F 2)] = 0.049
  • wR(F 2) = 0.134
  • S = 1.03
  • 4063 reflections
  • 237 parameters
  • H-atom parameters constrained
  • Δρmax = 0.17 e Å−3
  • Δρmin = −0.15 e Å−3

Data collection: RAPID-AUTO (Rigaku, 1998 [triangle]); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: SHELXTL (Bruker, 1997 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536807064768/gk2120sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807064768/gk2120Isup2.hkl

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

Acknowledgments

This project was supported by the Talent Fund of Ningbo University (grant No. 2006668).

supplementary crystallographic information

Comment

Schiff bases have been used extensively as ligands in the field of coordination chemistry. Some of the reasons are that the intramolecular hydrogen bond between the O and N atoms plays an important role in the formation of metal complexes, and that Schiff base compounds show photochromism and thermochromism in the solid state by proton transfer from the hydroxyl O atom to the imine N atom (Cohen et al., 1964). On the basis of structural studies on photochromic and thermochromic salicylaldimine derivatives it was concluded that there is a significant difference in crydtal packing of these molecules: molecules exhibiting thermochromism are planar while those showing photochromism are non-planar (Cohen et al., 1964). In other words, photochromic salicylideneanilines are packed rather loosely in the crystal, in which nonplanar molecules may undergo some conformational changes, while thermochromic salicylideneanilines are packed tightly to form one-dimensional columns. With the aim of gaining a deeper insight into the structural aspects responsible for the observed phenomenon in the solid state, conformational and crystallographic analysis of the non-planar tetra-dentate title compound (I), has been carried out and the results are presented in this paper.

The molecular structure of (I) is illustrated in Fig. 1.

The title molecule is not planar. The salicylaldimine groups C1—C7 (A) and C16—C22 (B) are twisted relative to the phenylene spacer and the angles between the spacer and the salicylaldimino parts A and B are 53.92 (1) and 3.62 (1)°, respectively. The dihedral angle between the salicylaldimine groups A and B is equal to 56.23 (2)°.

In the title molecule there are intramolecular hydrogen bonds between between O1 and N1 and between O2 and N2 atoms (Table 1). Clearly, the enolimine tautomer is favoured over the ketamine form. The crystal packing is stabilized by weak intermolecular hydrogen bonds C—H···O (Table 1) and π···π stacking interactions between benzene ring and salicylaldimine group B.

Experimental

1,2-Phenylenediamine(0.01 mol, 1.08 g) and 5-methylsalicylaldehyde (0.02 mol, 2.76 g) were dissolved in ethanol and the solution was refluxed for 3 h. After evaporation, a crude product was recrystallized twice from ethanol to give a pure yellow product. Yield: 90.1%. Melting point: 494–496 K. Calcd. for C22H20N2O2: C, 76.72; H, 5.85; N, 8.13; Found: C, 76.44; H, 5.75; N, 8.07%.

Refinement

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms (C—H = 0.93 Å or 0.96 Å; O—H = 0.82 Å) and Uiso(H) values equal to 1.2Ueq(C) or 1.5Ueq(O).

Figures

Fig. 1.
The structure of (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme.
Fig. 2.
A view of crystal packing of (I).

Crystal data

C22H20N2O2F000 = 728
Mr = 344.40Dx = 1.260 Mg m3
Monoclinic, P21/cMelting point = 494–496 K
Hall symbol: -P 2ybcMo Kα radiation λ = 0.71073 Å
a = 6.0835 (12) ÅCell parameters from 8652 reflections
b = 16.207 (3) Åθ = 1.0–27.4º
c = 18.607 (4) ŵ = 0.08 mm1
β = 98.28 (3)ºT = 296 (2) K
V = 1815.4 (6) Å3Block, orange
Z = 40.33 × 0.29 × 0.21 mm

Data collection

Rigaku R-AXIS RAPID diffractometer4063 independent reflections
Radiation source: fine-focus sealed tube2571 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.037
Detector resolution: 0 pixels mm-1θmax = 27.4º
T = 296(2) Kθmin = 3.4º
ω scansh = −7→7
Absorption correction: multi-scan(ABSCOR; Higashi, 1995)k = −21→21
Tmin = 0.971, Tmax = 0.985l = −24→23
17288 measured reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.049H-atom parameters constrained
wR(F2) = 0.134  w = 1/[σ2(Fo2) + (0.0577P)2 + 0.235P] where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.003
4063 reflectionsΔρmax = 0.17 e Å3
237 parametersΔρmin = −0.15 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

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 (Å2)

xyzUiso*/Ueq
N10.4005 (2)0.75760 (9)0.02195 (8)0.0530 (4)
O10.1506 (2)0.88529 (8)−0.01297 (7)0.0731 (4)
H10.25200.8526−0.01550.110*
C10.7385 (4)1.07183 (14)−0.30763 (12)0.0790 (6)
H1B0.88851.0532−0.30720.118*
H1C0.73851.1210−0.27890.118*
H1D0.67291.0834−0.35660.118*
O20.2200 (2)0.82823 (8)−0.19143 (7)0.0677 (4)
H2A0.29210.8046−0.15680.101*
N20.5699 (2)0.78862 (9)−0.10188 (7)0.0535 (4)
C20.6061 (3)1.00555 (11)−0.27638 (9)0.0562 (4)
C30.3863 (3)0.99007 (11)−0.30589 (10)0.0606 (5)
H3A0.32321.0202−0.34620.073*
C40.2594 (3)0.93154 (11)−0.27725 (9)0.0586 (5)
H4A0.11260.9233−0.29790.070*
C50.3491 (3)0.88514 (11)−0.21800 (9)0.0508 (4)
C60.5724 (3)0.89744 (11)−0.18760 (8)0.0489 (4)
C70.6942 (3)0.95853 (11)−0.21748 (9)0.0564 (4)
H7A0.84060.9678−0.19680.068*
C80.6787 (3)0.84472 (11)−0.12984 (9)0.0534 (4)
H8A0.82890.8518−0.11280.064*
C90.6778 (3)0.72943 (10)−0.05323 (9)0.0509 (4)
C100.8666 (3)0.68766 (11)−0.06801 (10)0.0592 (5)
H10A0.93400.7028−0.10780.071*
C110.9537 (3)0.62385 (12)−0.02361 (10)0.0645 (5)
H11A1.08010.5962−0.03340.077*
C120.8537 (3)0.60120 (12)0.03489 (11)0.0677 (5)
H12A0.91060.55720.06380.081*
C130.6707 (3)0.64270 (11)0.05125 (10)0.0638 (5)
H13A0.60630.62710.09160.077*
C140.5802 (3)0.70811 (10)0.00797 (9)0.0510 (4)
C150.2992 (3)0.74716 (11)0.07654 (9)0.0540 (4)
H15A0.34310.70420.10860.065*
C160.1188 (3)0.79963 (10)0.09036 (9)0.0513 (4)
C170.0497 (3)0.86653 (11)0.04521 (10)0.0562 (4)
C18−0.1276 (3)0.91440 (12)0.05974 (11)0.0683 (5)
H18A−0.17300.95940.03030.082*
C19−0.2366 (3)0.89569 (12)0.11747 (11)0.0653 (5)
H19A−0.35550.92840.12630.078*
C20−0.1739 (3)0.82931 (11)0.16301 (10)0.0588 (5)
C210.0043 (3)0.78327 (11)0.14885 (9)0.0570 (4)
H21A0.05100.73930.17940.068*
C22−0.2979 (4)0.80766 (14)0.22487 (11)0.0806 (6)
H22A−0.45400.81630.21020.121*
H22B−0.24700.84210.26590.121*
H22C−0.27160.75080.23790.121*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N10.0519 (8)0.0496 (8)0.0578 (9)0.0005 (6)0.0092 (7)0.0059 (7)
O10.0760 (9)0.0649 (9)0.0824 (9)0.0113 (7)0.0251 (8)0.0276 (7)
C10.0820 (14)0.0738 (14)0.0866 (15)0.0036 (11)0.0310 (12)0.0169 (11)
O20.0551 (7)0.0724 (9)0.0716 (8)−0.0099 (6)−0.0041 (6)0.0130 (7)
N20.0525 (8)0.0601 (9)0.0469 (8)0.0036 (7)0.0038 (7)0.0036 (7)
C20.0619 (11)0.0549 (10)0.0544 (10)0.0081 (8)0.0171 (9)0.0018 (8)
C30.0725 (12)0.0574 (11)0.0504 (10)0.0143 (9)0.0041 (9)0.0025 (8)
C40.0548 (10)0.0607 (11)0.0565 (10)0.0056 (8)−0.0045 (9)−0.0004 (9)
C50.0512 (9)0.0506 (10)0.0500 (9)0.0011 (8)0.0053 (8)−0.0026 (7)
C60.0475 (9)0.0560 (10)0.0437 (8)0.0048 (7)0.0078 (7)−0.0014 (7)
C70.0471 (9)0.0641 (11)0.0589 (10)0.0022 (8)0.0107 (8)−0.0010 (9)
C80.0473 (9)0.0643 (11)0.0475 (9)0.0049 (8)0.0036 (8)−0.0017 (8)
C90.0511 (9)0.0503 (10)0.0490 (9)0.0011 (8)−0.0009 (8)−0.0022 (8)
C100.0597 (11)0.0635 (12)0.0533 (10)0.0061 (9)0.0047 (9)−0.0083 (9)
C110.0679 (12)0.0572 (11)0.0660 (12)0.0145 (9)0.0013 (10)−0.0120 (9)
C120.0792 (13)0.0463 (10)0.0740 (13)0.0137 (9)−0.0010 (11)0.0017 (9)
C130.0757 (13)0.0504 (10)0.0653 (11)0.0052 (9)0.0107 (10)0.0085 (9)
C140.0522 (9)0.0442 (9)0.0549 (10)−0.0001 (7)0.0023 (8)−0.0009 (7)
C150.0586 (10)0.0496 (10)0.0521 (10)0.0027 (8)0.0022 (9)0.0041 (8)
C160.0555 (10)0.0460 (9)0.0512 (9)−0.0030 (7)0.0031 (8)0.0001 (7)
C170.0591 (10)0.0482 (10)0.0620 (11)−0.0025 (8)0.0109 (9)0.0058 (8)
C180.0733 (12)0.0493 (11)0.0827 (13)0.0088 (9)0.0126 (11)0.0116 (10)
C190.0643 (11)0.0550 (11)0.0779 (13)0.0041 (9)0.0152 (10)−0.0081 (10)
C200.0677 (11)0.0542 (11)0.0555 (10)−0.0013 (9)0.0120 (9)−0.0073 (8)
C210.0695 (11)0.0522 (10)0.0484 (10)0.0027 (9)0.0052 (9)0.0031 (8)
C220.0953 (16)0.0850 (16)0.0665 (13)0.0006 (12)0.0286 (12)−0.0062 (11)

Geometric parameters (Å, °)

N1—C151.273 (2)C9—C141.401 (2)
N1—C141.410 (2)C10—C111.381 (3)
O1—C171.353 (2)C10—H10A0.9300
O1—H10.8200C11—C121.371 (3)
C1—C21.509 (3)C11—H11A0.9300
C1—H1B0.9600C12—C131.372 (3)
C1—H1C0.9600C12—H12A0.9300
C1—H1D0.9600C13—C141.396 (2)
O2—C51.350 (2)C13—H13A0.9300
O2—H2A0.8200C15—C161.440 (2)
N2—C81.279 (2)C15—H15A0.9300
N2—C91.414 (2)C16—C171.399 (2)
C2—C71.379 (2)C16—C211.399 (2)
C2—C31.393 (3)C17—C181.387 (3)
C3—C41.378 (3)C18—C191.375 (3)
C3—H3A0.9300C18—H18A0.9300
C4—C51.380 (2)C19—C201.388 (3)
C4—H4A0.9300C19—H19A0.9300
C5—C61.409 (2)C20—C211.373 (3)
C6—C71.399 (2)C20—C221.505 (3)
C6—C81.450 (2)C21—H21A0.9300
C7—H7A0.9300C22—H22A0.9600
C8—H8A0.9300C22—H22B0.9600
C9—C101.394 (2)C22—H22C0.9600
C15—N1—C14123.29 (15)C12—C11—H11A120.0
C17—O1—H1109.5C10—C11—H11A120.0
C2—C1—H1B109.5C11—C12—C13120.79 (18)
C2—C1—H1C109.5C11—C12—H12A119.6
H1B—C1—H1C109.5C13—C12—H12A119.6
C2—C1—H1D109.5C12—C13—C14120.65 (18)
H1B—C1—H1D109.5C12—C13—H13A119.7
H1C—C1—H1D109.5C14—C13—H13A119.7
C5—O2—H2A109.5C13—C14—C9118.56 (16)
C8—N2—C9121.53 (15)C13—C14—N1125.29 (16)
C7—C2—C3117.08 (17)C9—C14—N1116.11 (15)
C7—C2—C1122.12 (18)N1—C15—C16122.20 (16)
C3—C2—C1120.80 (17)N1—C15—H15A118.9
C4—C3—C2122.07 (17)C16—C15—H15A118.9
C4—C3—H3A119.0C17—C16—C21118.29 (16)
C2—C3—H3A119.0C17—C16—C15121.41 (16)
C3—C4—C5120.33 (17)C21—C16—C15120.28 (16)
C3—C4—H4A119.8O1—C17—C18119.03 (16)
C5—C4—H4A119.8O1—C17—C16121.53 (16)
O2—C5—C4118.72 (15)C18—C17—C16119.43 (16)
O2—C5—C6121.86 (15)C19—C18—C17120.35 (18)
C4—C5—C6119.41 (16)C19—C18—H18A119.8
C7—C6—C5118.43 (15)C17—C18—H18A119.8
C7—C6—C8120.42 (16)C18—C19—C20121.79 (18)
C5—C6—C8121.03 (16)C18—C19—H19A119.1
C2—C7—C6122.65 (17)C20—C19—H19A119.1
C2—C7—H7A118.7C21—C20—C19117.33 (17)
C6—C7—H7A118.7C21—C20—C22121.10 (18)
N2—C8—C6121.25 (16)C19—C20—C22121.57 (18)
N2—C8—H8A119.4C20—C21—C16122.80 (17)
C6—C8—H8A119.4C20—C21—H21A118.6
C10—C9—C14119.88 (16)C16—C21—H21A118.6
C10—C9—N2121.52 (15)C20—C22—H22A109.5
C14—C9—N2118.39 (15)C20—C22—H22B109.5
C11—C10—C9120.10 (17)H22A—C22—H22B109.5
C11—C10—H10A119.9C20—C22—H22C109.5
C9—C10—H10A119.9H22A—C22—H22C109.5
C12—C11—C10119.97 (18)H22B—C22—H22C109.5

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H1···N10.821.872.595 (2)147
O2—H2A···N20.821.862.5880 (19)147
C8—H8A···O1i0.932.563.407 (2)152
C18—H18A···O1ii0.932.543.359 (2)146

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GK2120).

References

  • Bruker (1997). SHELXTL Version 5.10. Bruker AXS Inc., Madison, Wisconsin, USA.
  • Cohen, M. D., Schmidt, G. M. J. & Flavian, S. (1964). J. Chem. Soc. pp. 2041–2043.
  • Higashi, T. (1995). ABSCOR Rigaku Corporation, Tokyo, Japan.
  • Rigaku (1998). RAPID-AUTO Rigaku Corporation, Tokyo, Japan.
  • Rigaku/MSC (2002). CrystalStructure Rigaku/MSC Inc., The Woodlands, Texas, USA.
  • Sheldrick, G. M. (1997). SHELXS97 and SHELXL97 University of Göttingen, Germany.

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