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Acta Cryst. (2010). E66, o85    [ doi:10.1107/S1600536809051800 ]

(E)-4-Methyl-2-{[tris(hydroxymethyl)methyl]iminiomethyl}phenolate

G. Özdemir Tari, H. Tanak, M. Macit, F. Ersahin and S. Isik

Abstract top

In the zwitterionic title compound, C12H17NO4, an intramolecular N-H...O hydrogen bond generates a six-membered ring, producing an S(6) ring. In the crystal structure, molecules are linked by intermolecular C-H...O and O-H...O interactions.

Comment top

Schiff bases are used as starting materials in the synthesis of important drugs, such as antibiotics and antiallergic, antiphlogistic, and antitumor substances (Barton et al., 1979; Layer, 1963; Ingold 1969). On the industrial scale, they have a wide range of applications, such as dyes and pigments (Taggi et al., 2002). Schiff bases have also been employed as ligands for the complexation of metal ions (Aydoğan et al., 2001). There are two characteristic properties of Schiff bases, viz. photochromism and thermochromism (Cohen et al., 1964). In general, Schiff bases based on salicylic alehyde display two possible tautomeric forms, the iminomethyl-phenol (OH) and the aminomethylene-cyclohexa-2,4-dienone (NH) forms. Depending on the tautomers, two types of intramolecular hydrogen bonds are observed in Schiff bases: O—H···N in the former and N—H···O in the latter tautomer. Another form of the Schiff base compounds is also regarded to be zwitterionic showing an ionic intramolecular hydrogen bond (N+—H···O-) and this form is rarely seen in the solid state. The NH form of Schiff bases in the solid state can be regarded as a resonance hybrid of two canonical structures, the aminomethylene-cyclohexa-2,4-dienone and the zwitterionic form (Ogawa, et al.,2003).

The crystal and molecular structure of the title compound, C12H17NO4, has been synthesized and x-ray single-crystal structure determination has been performed. The title molecule exists in a zwitterionic form with a strong intramolecular N+—H···O- hydrogen bond between the NH+ and the phenolate O-. The bond lengths and angles are within normal ranges (Allen et al.,1987). The C8=N1 [1.286 (2) Å] and C1—O1 [1.307 (2) Å] bonds may be compared with the corresponding values [1.295 (2) and 1.295 (2) Å] in a similar zwitterionic structure (Yüce et al., 2006). Nevertheless, carbon carbon bonds in the phenyl group are slightly alternating reminding of the aminomethylene-cyclohexa-2,4-dienone canonical structure.

As it is expected, the salicylaldimine subunit of the molecule is almost perfectly planar whereas C9 as a sp3 hybridised carbon is tetrahedrally coordinated (Fig. 1). Torsion angles C8—N1—C9—C10, C8—N1—C9—C11 and C8—N1—C9—C12 are -20.3 (2)°, 100.8 (1)° and -140.9 (1)°, respectively. Bond lengths and angles in the planar salicylaldimine fragment and in the C(CH2OH)3 group of the studied compound are in a good agreement with the related compounds (Allen et al., 1987; Yüce et al., 2006).

An intramolecular N1—H1···O1 hydrogen bond generates a six-membered ring, producing an S(6) ring motif (Bernstein et al., 1995). In the crystal structure, molecules are linked together by intermolecular C—H···O and O—H···O interactions (Fig. 2).

Related literature top

For the properties and uses of Schiff bases, see: Aydoğan et al. (2001); Barton & Ollis (1979); Layer (1963); Ingold (1969); Cohen et al. (1964); Ogawa & Harada (2003); Taggi et al. (2002). For hydrogen-bond motifs, see: Bernstein et al. (1995). For comparative bond lengths, see: Allen et al. (1987); Yüce et al. (2006).

Experimental top

The title compound (E)-2-hydroxymethyl-2-[(2-oxo-5-methyl-benzylidene) -ammonium]-propane-1,3-diol was prepared by refluxing a mixture of 5-methylsalicylaldehyde (0.05 g 0.36 mmol) and tris(hydroxymethyl)aminomethane (0.0435 g 0.25 mmol) in 40 ml ethanol for one hour. Crystals of the title compound suitable for x-ray analysis were obtained from n-hexane/methanol (1:1) by slow evaporation (yield 88%; m.p. 429–430 K).

Refinement top

The position of H1 was obtained from a difference Fourier map and was refined freely. Other H atoms were positioned geometrically and treated using a riding model, fixing the bond lengths at 0.82 Å for OH, at 0.93 Å for aromatic CH, at 0.96 Å for CH3, at 0.97 Å for CH2. The displacement parameters of the H atoms were constrained as Uiso(H)= 1.2Ueq (1.5Ueq for methyl) of the parent atom.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing the atom-numbering scheme and 30% probability diplacement ellipsoids.
[Figure 2] Fig. 2. The crystal packing of the title compound. Intra- and intermolecular hydrogen bonds are shown as dashed lines.
(E)-4-Methyl-2-{[tris(hydroxymethyl)methyl]iminiomethyl}phenolate top
Crystal data top
C12H17NO4Z = 2
Mr = 239.27F(000) = 256
Triclinic, P1Dx = 1.299 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.7501 (6) ÅCell parameters from 13032 reflections
b = 8.5036 (8) Åθ = 1.9–28.0°
c = 11.129 (1) ŵ = 0.10 mm−1
α = 87.584 (8)°T = 296 K
β = 77.192 (8)°PRISM., yellow
γ = 79.215 (8)°0.80 × 0.48 × 0.21 mm
V = 611.9 (1) Å3
Data collection top
STOE IPDS II
diffractometer		2409 independent reflections
Radiation source: fine-focus sealed tube2001 reflections with I > 2σ(I)
graphiteRint = 0.022
Detector resolution: 6.67 pixels mm-1θmax = 26.0°, θmin = 1.9°
rotation method scansh = −8→8
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		k = −10→10
Tmin = 0.942, Tmax = 0.979l = −13→13
8321 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.105 w = 1/[σ2(Fo2) + (0.0534P)2 + 0.0953P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
2409 reflectionsΔρmax = 0.25 e Å−3
160 parametersΔρmin = −0.21 e Å−3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.046 (8)
Crystal data top
C12H17NO4γ = 79.215 (8)°
Mr = 239.27V = 611.9 (1) Å3
Triclinic, P1Z = 2
a = 6.7501 (6) ÅMo Kα radiation
b = 8.5036 (8) ŵ = 0.10 mm−1
c = 11.129 (1) ÅT = 296 K
α = 87.584 (8)°0.80 × 0.48 × 0.21 mm
β = 77.192 (8)°
Data collection top
STOE IPDS II
diffractometer		2409 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		2001 reflections with I > 2σ(I)
Tmin = 0.942, Tmax = 0.979Rint = 0.022
8321 measured reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.036H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.105Δρmax = 0.25 e Å−3
S = 1.09Δρmin = −0.21 e Å−3
2409 reflectionsAbsolute structure: ?
160 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. 339 frames, detector distance = 100 mm

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
C10.2299 (2)0.70721 (15)0.73471 (12)0.0388 (3)
C20.2401 (3)0.6812 (2)0.60930 (15)0.0587 (4)
H20.13270.64400.58650.070*
C30.4045 (3)0.7094 (3)0.52063 (15)0.0667 (5)
H30.40620.68880.43900.080*
C40.5709 (3)0.7680 (2)0.54645 (14)0.0570 (4)
C50.5658 (2)0.79155 (18)0.66829 (13)0.0476 (4)
H50.67520.82840.68910.057*
C60.4002 (2)0.76175 (15)0.76301 (12)0.0377 (3)
C70.7462 (3)0.8029 (3)0.44497 (17)0.0820 (6)
H7A0.85090.83310.48040.123*
H7B0.69540.88870.39460.123*
H7C0.80400.70890.39520.123*
C80.4134 (2)0.78295 (15)0.88719 (12)0.0364 (3)
H80.52460.82440.90090.044*
C90.27900 (19)0.76614 (14)1.11183 (11)0.0333 (3)
C100.4917 (2)0.77744 (17)1.13130 (13)0.0422 (3)
H10A0.53510.87251.09100.051*
H10B0.48690.78531.21860.051*
C110.1251 (2)0.91827 (15)1.15916 (13)0.0409 (3)
H11A−0.01060.91141.14650.049*
H11B0.11480.93071.24670.049*
C120.2064 (2)0.61933 (16)1.17826 (13)0.0395 (3)
H12A0.30710.52381.15010.047*
H12B0.19340.62961.26630.047*
N10.28000 (16)0.74792 (12)0.98133 (9)0.0325 (3)
O10.07182 (14)0.68314 (10)0.82072 (9)0.0412 (3)
O20.63352 (16)0.64022 (13)1.08193 (13)0.0655 (4)
H140.74850.64601.09220.098*
O30.19503 (15)1.05030 (11)1.09428 (10)0.0510 (3)
H130.11391.13271.11900.077*
O40.01450 (14)0.60604 (11)1.15400 (9)0.0452 (3)
H4−0.02440.52731.18970.068*
H10.179 (3)0.7122 (19)0.9641 (14)0.047 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0392 (7)0.0321 (6)0.0448 (7)−0.0052 (5)−0.0094 (6)0.0000 (5)
C20.0602 (10)0.0732 (11)0.0495 (9)−0.0187 (8)−0.0198 (8)−0.0046 (8)
C30.0721 (12)0.0905 (13)0.0386 (8)−0.0158 (10)−0.0134 (8)−0.0033 (8)
C40.0544 (10)0.0684 (10)0.0420 (8)−0.0070 (8)−0.0013 (7)0.0030 (7)
C50.0414 (8)0.0553 (8)0.0445 (8)−0.0127 (6)−0.0033 (6)0.0017 (6)
C60.0381 (7)0.0357 (6)0.0382 (7)−0.0079 (5)−0.0045 (5)−0.0010 (5)
C70.0720 (13)0.1168 (18)0.0473 (10)−0.0174 (12)0.0065 (9)0.0066 (10)
C80.0331 (6)0.0340 (6)0.0426 (7)−0.0099 (5)−0.0056 (5)−0.0014 (5)
C90.0315 (6)0.0337 (6)0.0355 (6)−0.0097 (5)−0.0060 (5)0.0001 (5)
C100.0380 (7)0.0470 (7)0.0461 (7)−0.0147 (6)−0.0133 (6)0.0016 (6)
C110.0389 (7)0.0360 (7)0.0450 (7)−0.0114 (5)0.0017 (6)−0.0042 (5)
C120.0370 (7)0.0382 (7)0.0457 (7)−0.0126 (5)−0.0109 (6)0.0078 (5)
N10.0289 (5)0.0316 (5)0.0380 (6)−0.0087 (4)−0.0063 (4)−0.0013 (4)
O10.0373 (5)0.0354 (5)0.0522 (6)−0.0108 (4)−0.0086 (4)−0.0016 (4)
O20.0382 (6)0.0497 (6)0.1130 (10)−0.0030 (5)−0.0300 (6)−0.0023 (6)
O30.0417 (6)0.0313 (5)0.0726 (7)−0.0088 (4)0.0055 (5)−0.0010 (4)
O40.0361 (5)0.0378 (5)0.0659 (7)−0.0156 (4)−0.0140 (4)0.0094 (4)
Geometric parameters (Å, °) top
C1—O11.3071 (16)C9—N11.4654 (16)
C1—C21.407 (2)C9—C101.5197 (17)
C1—C61.4174 (19)C9—C121.5282 (17)
C2—C31.363 (3)C9—C111.5305 (18)
C2—H20.9300C10—O21.4080 (19)
C3—C41.399 (3)C10—H10A0.9700
C3—H30.9300C10—H10B0.9700
C4—C51.371 (2)C11—O31.4085 (16)
C4—C71.508 (2)C11—H11A0.9700
C5—C61.4094 (19)C11—H11B0.9700
C5—H50.9300C12—O41.4060 (16)
C6—C81.4255 (18)C12—H12A0.9700
C7—H7A0.9600C12—H12B0.9700
C7—H7B0.9600N1—H10.858 (18)
C7—H7C0.9600O2—H140.8200
C8—N11.2856 (16)O3—H130.8200
C8—H80.9300O4—H40.8200
O1—C1—C2122.02 (13)C10—C9—C12110.25 (10)
O1—C1—C6121.62 (12)N1—C9—C11107.87 (10)
C2—C1—C6116.36 (13)C10—C9—C11109.93 (11)
C3—C2—C1121.25 (15)C12—C9—C11110.19 (11)
C3—C2—H2119.4O2—C10—C9109.24 (11)
C1—C2—H2119.4O2—C10—H10A109.8
C2—C3—C4123.19 (15)C9—C10—H10A109.8
C2—C3—H3118.4O2—C10—H10B109.8
C4—C3—H3118.4C9—C10—H10B109.8
C5—C4—C3116.52 (15)H10A—C10—H10B108.3
C5—C4—C7122.08 (16)O3—C11—C9108.51 (10)
C3—C4—C7121.40 (16)O3—C11—H11A110.0
C4—C5—C6122.10 (14)C9—C11—H11A110.0
C4—C5—H5118.9O3—C11—H11B110.0
C6—C5—H5118.9C9—C11—H11B110.0
C5—C6—C1120.53 (12)H11A—C11—H11B108.4
C5—C6—C8117.94 (12)O4—C12—C9109.49 (10)
C1—C6—C8121.50 (12)O4—C12—H12A109.8
C4—C7—H7A109.5C9—C12—H12A109.8
C4—C7—H7B109.5O4—C12—H12B109.8
H7A—C7—H7B109.5C9—C12—H12B109.8
C4—C7—H7C109.5H12A—C12—H12B108.2
H7A—C7—H7C109.5C8—N1—C9127.73 (11)
H7B—C7—H7C109.5C8—N1—H1114.8 (10)
N1—C8—C6123.60 (12)C9—N1—H1117.5 (10)
N1—C8—H8118.2C10—O2—H14109.5
C6—C8—H8118.2C11—O3—H13109.5
N1—C9—C10111.90 (10)C12—O4—H4109.5
N1—C9—C12106.62 (10)
O1—C1—C2—C3178.89 (16)C1—C6—C8—N13.4 (2)
C6—C1—C2—C3−0.9 (2)N1—C9—C10—O2−57.33 (14)
C1—C2—C3—C4−1.2 (3)C12—C9—C10—O261.16 (15)
C2—C3—C4—C52.2 (3)C11—C9—C10—O2−177.17 (11)
C2—C3—C4—C7−177.89 (19)N1—C9—C11—O3−62.87 (13)
C3—C4—C5—C6−1.3 (2)C10—C9—C11—O359.40 (14)
C7—C4—C5—C6178.83 (16)C12—C9—C11—O3−178.89 (10)
C4—C5—C6—C1−0.7 (2)N1—C9—C12—O4−55.27 (13)
C4—C5—C6—C8177.23 (13)C10—C9—C12—O4−176.94 (11)
O1—C1—C6—C5−178.02 (12)C11—C9—C12—O461.54 (14)
C2—C1—C6—C51.7 (2)C6—C8—N1—C9−179.57 (11)
O1—C1—C6—C84.15 (19)C10—C9—N1—C8−20.27 (17)
C2—C1—C6—C8−176.10 (13)C12—C9—N1—C8−140.89 (12)
C5—C6—C8—N1−174.53 (13)C11—C9—N1—C8100.77 (14)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O1i0.821.892.621 (1)148
O3—H13···O1ii0.821.862.679 (1)178
O2—H14···O4iii0.822.032.821 (1)163
C8—H8···O3iv0.932.353.272 (2)171
C10—H10A···O3iv0.972.583.379 (2)140
N1—H1···O10.86 (2)1.93 (2)2.638 (1)138 (1)
Symmetry codes: (i) −x, −y+1, −z+2; (ii) −x, −y+2, −z+2; (iii) x+1, y, z; (iv) −x+1, −y+2, −z+2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O1i0.821.892.621 (1)148
O3—H13···O1ii0.821.862.679 (1)178
O2—H14···O4iii0.822.032.821 (1)163
C8—H8···O3iv0.932.353.272 (2)171
C10—H10A···O3iv0.972.583.379 (2)140
N1—H1···O10.86 (2)1.93 (2)2.638 (1)138 (1)
Symmetry codes: (i) −x, −y+1, −z+2; (ii) −x, −y+2, −z+2; (iii) x+1, y, z; (iv) −x+1, −y+2, −z+2.
Acknowledgements top

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS II diffractometer (purchased under grant No. F279 of the University Research Fund).

references
References top

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