organic compounds
(S)-(+)-N-Benzylidene-1-(1-naphthyl)ethylamine
aDEP Facultad de Ciencias Químicas, UANL, Guerrero y Progreso S/N, Col. Treviño, 64570 Monterrey, N.L., Mexico, bLaboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico, and cUniversidad de la Cañada, Cd. Universitaria, 68540, Teotitlán de Flores Magón, Oax., Mexico
*Correspondence e-mail: sylvain_bernes@Hotmail.com
In the title chiral aldimine, C19H17N, the azomethine group is not fully conjugated with the phenyl substituent: the dihedral angle between phenyl and C*—N=C mean planes is φ3 = 23.0 (2)°. Compared with the earlier DFT-B3LYP/6–31 G(d) computations from the literature, the C=N—C*—C(naphthyl) torsion angle, found at φ2 = −118.0 (2)° in the X-ray structure, does not match the angle calculated for the potential minimum energy at φ2 = 0°. However, this angle is close to the second minimum at φ2 = −120° which is ca. 8.5 kJ mol−1 above the global energy minimum. Thus, the reported X-ray structure corresponds to the second most likely (according to DFT) conformer, allowing the existence of other polymorphs to be anticipated.
Related literature
For a typical synthesis of the title compound, see: Lee & Ahn (2002). For general background to solvent-free synthesis, see: Tanaka & Toda (2000). For the structures of related see: Espinosa Leija et al. (2009); Bernès et al. (2010). For the DFT study of the title compound (R enantiomer), see: Fukuda et al. (2007).
Experimental
Crystal data
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Data collection: XSCANS (Siemens, 1996); cell XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536811012980/ld2008sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811012980/ld2008Isup2.hkl
The title compound was prepared by reacting (S)-(–)-(1-naphthyl)ethylamine and benzaldehyde (Lee & Ahn, 2002), but at room temperature and using no solvent. The crude was recrystallized from EtOH affording colorless crystals of the title compound. Yield 94%; mp 79–81 oC. Analysis: [α]D25 = +233 (c 1, CHCl3). FT—IR (KBr): 1641 cm-1 (C=N). 1H NMR (400 MHz, CDCl3/TMS) δ = 1.71 (d, 3H, CH—CH3,), 5.31 (q, 1H, Ar—CH), 7.34–8.24 (m, 12H, Ar), 8.36 (s, 1H, H-C=N). 13C NMR (100 MHz, CDCl3/TMS) δ = 24.51 (CCH3), 65.51 (CHCH3), 123.56 (Ar), 123.97 (Ar), 125.26 (Ar), 125.64(Ar), 125.74 (Ar), 127.28 (Ar), 128.21 (Ar), 128.46 (Ar), 128.88 (Ar), 130.52 (Ar), 130.60 (Ar), 133.94 (Ar), 136.43 (Ar),141.12 (Ar), 159.55 (HC=N). MS—EI: m/z= 259 (M+).
All C-bonded H atoms were placed in idealized positions and refined as riding to their carrier C atoms, with bond lengths fixed to 0.93 (aromatic CH), 0.96 (methyl CH3), and 0.98 Å (methine CH). Isotropic displacement parameters were calculated as Uiso(H) = 1.5Ueq(C10) for the methyl group and Uiso(H) = 1.2Ueq(carrier atom) otherwise. The methyl group C10 was considered as a rigid group but was allowed to rotate about C9—C10 bond. The
was assigned from the known configuration of the chiral amine used as the starting material and confirmed by measring the and comparing with rotations reported in the litterature for both enantiomers. All measured Friedel pairs (223) were merged.Data collection: XSCANS (Siemens, 1996); cell
XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. The title molecule with displacement ellipsoids for non-H atoms shown at the 30% probability level. The scheme indicates the torsion angles used in the DFT study of Fukuda et al. (2007). |
C19H17N | F(000) = 276 |
Mr = 259.34 | Dx = 1.167 Mg m−3 |
Monoclinic, P21 | Melting point: 352 K |
Hall symbol: P 2yb | Mo Kα radiation, λ = 0.71073 Å |
a = 8.0761 (8) Å | Cell parameters from 80 reflections |
b = 7.7874 (8) Å | θ = 4.9–12.3° |
c = 11.7760 (11) Å | µ = 0.07 mm−1 |
β = 95.033 (7)° | T = 298 K |
V = 737.76 (13) Å3 | Irregular, colourless |
Z = 2 | 0.4 × 0.2 × 0.2 mm |
Siemens P4 diffractometer | Rint = 0.017 |
Radiation source: fine-focus sealed tube | θmax = 26.2°, θmin = 2.5° |
Graphite monochromator | h = −10→3 |
2θ/ω scans | k = −1→9 |
2470 measured reflections | l = −14→14 |
1595 independent reflections | 3 standard reflections every 97 reflections |
1276 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.034 | H-atom parameters constrained |
wR(F2) = 0.094 | w = 1/[σ2(Fo2) + (0.0477P)2 + 0.0347P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
1595 reflections | Δρmax = 0.09 e Å−3 |
183 parameters | Δρmin = −0.08 e Å−3 |
1 restraint | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 constraints | Extinction coefficient: 0.063 (8) |
Primary atom site location: structure-invariant direct methods | Absolute structure: 223 Friedel pairs merged |
C19H17N | V = 737.76 (13) Å3 |
Mr = 259.34 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 8.0761 (8) Å | µ = 0.07 mm−1 |
b = 7.7874 (8) Å | T = 298 K |
c = 11.7760 (11) Å | 0.4 × 0.2 × 0.2 mm |
β = 95.033 (7)° |
Siemens P4 diffractometer | Rint = 0.017 |
2470 measured reflections | 3 standard reflections every 97 reflections |
1595 independent reflections | intensity decay: 1% |
1276 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.034 | 1 restraint |
wR(F2) = 0.094 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.09 e Å−3 |
1595 reflections | Δρmin = −0.08 e Å−3 |
183 parameters | Absolute structure: 223 Friedel pairs merged |
x | y | z | Uiso*/Ueq | ||
N1 | 0.3971 (2) | 0.6059 (3) | 0.71942 (14) | 0.0646 (5) | |
C2 | 0.4226 (3) | 0.6094 (3) | 0.61588 (18) | 0.0643 (6) | |
H2A | 0.3363 | 0.6432 | 0.5631 | 0.077* | |
C3 | 0.5833 (3) | 0.5624 (3) | 0.57416 (18) | 0.0662 (6) | |
C4 | 0.6202 (4) | 0.6121 (4) | 0.4665 (2) | 0.0906 (8) | |
H4A | 0.5440 | 0.6761 | 0.4203 | 0.109* | |
C5 | 0.7722 (5) | 0.5659 (5) | 0.4274 (3) | 0.1090 (11) | |
H5A | 0.7989 | 0.6028 | 0.3561 | 0.131* | |
C6 | 0.8809 (4) | 0.4676 (5) | 0.4930 (3) | 0.1058 (12) | |
H6A | 0.9813 | 0.4356 | 0.4660 | 0.127* | |
C7 | 0.8442 (3) | 0.4155 (5) | 0.5982 (3) | 0.0977 (10) | |
H7A | 0.9188 | 0.3468 | 0.6423 | 0.117* | |
C8 | 0.6973 (3) | 0.4640 (4) | 0.6394 (2) | 0.0748 (7) | |
H8A | 0.6745 | 0.4301 | 0.7121 | 0.090* | |
C9 | 0.2278 (2) | 0.6405 (3) | 0.74826 (16) | 0.0583 (5) | |
H9A | 0.1547 | 0.6558 | 0.6781 | 0.070* | |
C10 | 0.1713 (3) | 0.4844 (3) | 0.8128 (2) | 0.0747 (7) | |
H10A | 0.1743 | 0.3844 | 0.7654 | 0.112* | |
H10B | 0.0599 | 0.5025 | 0.8328 | 0.112* | |
H10C | 0.2442 | 0.4681 | 0.8809 | 0.112* | |
C11 | 0.2202 (3) | 0.7992 (3) | 0.82185 (16) | 0.0538 (5) | |
C12 | 0.3561 (3) | 0.8538 (3) | 0.88883 (18) | 0.0648 (6) | |
H12A | 0.4567 | 0.7968 | 0.8856 | 0.078* | |
C13 | 0.3473 (3) | 0.9946 (3) | 0.9628 (2) | 0.0760 (7) | |
H13A | 0.4412 | 1.0271 | 1.0092 | 0.091* | |
C14 | 0.2046 (3) | 1.0830 (3) | 0.96724 (19) | 0.0729 (7) | |
H14A | 0.2011 | 1.1765 | 1.0161 | 0.087* | |
C15 | 0.0608 (3) | 1.0349 (3) | 0.89846 (17) | 0.0595 (5) | |
C16 | −0.0910 (3) | 1.1256 (3) | 0.90111 (19) | 0.0729 (7) | |
H16A | −0.0950 | 1.2215 | 0.9478 | 0.088* | |
C17 | −0.2301 (3) | 1.0758 (4) | 0.8373 (2) | 0.0776 (7) | |
H17A | −0.3285 | 1.1369 | 0.8407 | 0.093* | |
C18 | −0.2257 (3) | 0.9330 (4) | 0.7667 (2) | 0.0731 (7) | |
H18A | −0.3217 | 0.8987 | 0.7233 | 0.088* | |
C19 | −0.0826 (2) | 0.8434 (3) | 0.76058 (18) | 0.0618 (6) | |
H19A | −0.0822 | 0.7490 | 0.7122 | 0.074* | |
C20 | 0.0660 (2) | 0.8899 (3) | 0.82582 (16) | 0.0529 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0602 (10) | 0.0696 (13) | 0.0646 (10) | 0.0073 (10) | 0.0089 (8) | −0.0043 (10) |
C2 | 0.0694 (13) | 0.0571 (13) | 0.0670 (12) | 0.0072 (12) | 0.0095 (11) | −0.0043 (11) |
C3 | 0.0726 (14) | 0.0565 (12) | 0.0718 (12) | −0.0021 (11) | 0.0185 (11) | −0.0127 (11) |
C4 | 0.121 (2) | 0.0679 (16) | 0.0887 (16) | 0.0076 (18) | 0.0422 (16) | −0.0017 (14) |
C5 | 0.139 (3) | 0.084 (2) | 0.116 (2) | −0.017 (2) | 0.074 (2) | −0.023 (2) |
C6 | 0.0783 (18) | 0.100 (2) | 0.145 (3) | −0.0151 (19) | 0.0411 (19) | −0.059 (2) |
C7 | 0.0638 (15) | 0.112 (3) | 0.117 (2) | 0.0058 (16) | 0.0057 (15) | −0.052 (2) |
C8 | 0.0638 (14) | 0.0823 (17) | 0.0782 (13) | 0.0047 (14) | 0.0061 (11) | −0.0211 (13) |
C9 | 0.0544 (11) | 0.0602 (12) | 0.0606 (11) | 0.0038 (11) | 0.0073 (9) | −0.0060 (11) |
C10 | 0.0847 (16) | 0.0558 (14) | 0.0842 (15) | −0.0062 (13) | 0.0114 (12) | −0.0021 (13) |
C11 | 0.0571 (11) | 0.0528 (12) | 0.0530 (10) | −0.0038 (10) | 0.0127 (9) | 0.0041 (9) |
C12 | 0.0600 (13) | 0.0637 (13) | 0.0708 (12) | −0.0029 (12) | 0.0060 (11) | 0.0000 (12) |
C13 | 0.0773 (17) | 0.0729 (17) | 0.0765 (14) | −0.0175 (15) | −0.0008 (12) | −0.0106 (14) |
C14 | 0.0912 (17) | 0.0565 (14) | 0.0723 (13) | −0.0121 (13) | 0.0155 (12) | −0.0119 (11) |
C15 | 0.0730 (14) | 0.0493 (11) | 0.0587 (11) | −0.0047 (11) | 0.0209 (10) | 0.0048 (10) |
C16 | 0.0884 (18) | 0.0584 (13) | 0.0768 (14) | 0.0041 (14) | 0.0341 (13) | −0.0024 (13) |
C17 | 0.0715 (16) | 0.0747 (17) | 0.0901 (15) | 0.0131 (14) | 0.0269 (13) | 0.0072 (14) |
C18 | 0.0605 (13) | 0.0809 (17) | 0.0794 (14) | 0.0022 (13) | 0.0145 (11) | 0.0021 (13) |
C19 | 0.0601 (13) | 0.0612 (13) | 0.0655 (11) | −0.0024 (11) | 0.0139 (10) | −0.0031 (11) |
C20 | 0.0591 (11) | 0.0495 (11) | 0.0520 (9) | −0.0052 (9) | 0.0166 (8) | 0.0045 (9) |
N1—C2 | 1.255 (2) | C10—H10C | 0.9600 |
N1—C9 | 1.462 (3) | C11—C12 | 1.362 (3) |
C2—C3 | 1.473 (3) | C11—C20 | 1.436 (3) |
C2—H2A | 0.9300 | C12—C13 | 1.405 (3) |
C3—C8 | 1.379 (3) | C12—H12A | 0.9300 |
C3—C4 | 1.383 (3) | C13—C14 | 1.348 (3) |
C4—C5 | 1.395 (4) | C13—H13A | 0.9300 |
C4—H4A | 0.9300 | C14—C15 | 1.407 (3) |
C5—C6 | 1.355 (5) | C14—H14A | 0.9300 |
C5—H5A | 0.9300 | C15—C16 | 1.418 (3) |
C6—C7 | 1.361 (5) | C15—C20 | 1.420 (3) |
C6—H6A | 0.9300 | C16—C17 | 1.352 (3) |
C7—C8 | 1.373 (3) | C16—H16A | 0.9300 |
C7—H7A | 0.9300 | C17—C18 | 1.391 (4) |
C8—H8A | 0.9300 | C17—H17A | 0.9300 |
C9—C11 | 1.514 (3) | C18—C19 | 1.358 (3) |
C9—C10 | 1.525 (3) | C18—H18A | 0.9300 |
C9—H9A | 0.9800 | C19—C20 | 1.414 (3) |
C10—H10A | 0.9600 | C19—H19A | 0.9300 |
C10—H10B | 0.9600 | ||
C2—N1—C9 | 117.30 (18) | H10A—C10—H10C | 109.5 |
N1—C2—C3 | 122.9 (2) | H10B—C10—H10C | 109.5 |
N1—C2—H2A | 118.5 | C12—C11—C20 | 118.99 (19) |
C3—C2—H2A | 118.5 | C12—C11—C9 | 121.04 (19) |
C8—C3—C4 | 118.6 (2) | C20—C11—C9 | 119.90 (18) |
C8—C3—C2 | 121.2 (2) | C11—C12—C13 | 121.4 (2) |
C4—C3—C2 | 120.2 (2) | C11—C12—H12A | 119.3 |
C3—C4—C5 | 119.8 (3) | C13—C12—H12A | 119.3 |
C3—C4—H4A | 120.1 | C14—C13—C12 | 120.8 (2) |
C5—C4—H4A | 120.1 | C14—C13—H13A | 119.6 |
C6—C5—C4 | 120.2 (3) | C12—C13—H13A | 119.6 |
C6—C5—H5A | 119.9 | C13—C14—C15 | 120.5 (2) |
C4—C5—H5A | 119.9 | C13—C14—H14A | 119.8 |
C5—C6—C7 | 120.4 (3) | C15—C14—H14A | 119.8 |
C5—C6—H6A | 119.8 | C14—C15—C16 | 121.8 (2) |
C7—C6—H6A | 119.8 | C14—C15—C20 | 119.5 (2) |
C6—C7—C8 | 120.2 (3) | C16—C15—C20 | 118.7 (2) |
C6—C7—H7A | 119.9 | C17—C16—C15 | 121.5 (2) |
C8—C7—H7A | 119.9 | C17—C16—H16A | 119.2 |
C7—C8—C3 | 120.8 (3) | C15—C16—H16A | 119.2 |
C7—C8—H8A | 119.6 | C16—C17—C18 | 119.9 (2) |
C3—C8—H8A | 119.6 | C16—C17—H17A | 120.1 |
N1—C9—C11 | 111.65 (18) | C18—C17—H17A | 120.1 |
N1—C9—C10 | 107.2 (2) | C19—C18—C17 | 120.6 (2) |
C11—C9—C10 | 109.68 (15) | C19—C18—H18A | 119.7 |
N1—C9—H9A | 109.4 | C17—C18—H18A | 119.7 |
C11—C9—H9A | 109.4 | C18—C19—C20 | 121.7 (2) |
C10—C9—H9A | 109.4 | C18—C19—H19A | 119.2 |
C9—C10—H10A | 109.5 | C20—C19—H19A | 119.2 |
C9—C10—H10B | 109.5 | C19—C20—C15 | 117.57 (19) |
H10A—C10—H10B | 109.5 | C19—C20—C11 | 123.62 (18) |
C9—C10—H10C | 109.5 | C15—C20—C11 | 118.81 (18) |
C9—N1—C2—C3 | −174.6 (2) | C11—C12—C13—C14 | −1.9 (4) |
N1—C2—C3—C8 | 19.9 (4) | C12—C13—C14—C15 | 0.6 (4) |
N1—C2—C3—C4 | −162.2 (3) | C13—C14—C15—C16 | −179.9 (2) |
C8—C3—C4—C5 | −1.6 (4) | C13—C14—C15—C20 | 1.4 (3) |
C2—C3—C4—C5 | −179.5 (2) | C14—C15—C16—C17 | −178.0 (2) |
C3—C4—C5—C6 | 2.3 (5) | C20—C15—C16—C17 | 0.7 (3) |
C4—C5—C6—C7 | −1.1 (5) | C15—C16—C17—C18 | −0.3 (4) |
C5—C6—C7—C8 | −0.8 (5) | C16—C17—C18—C19 | −0.4 (4) |
C6—C7—C8—C3 | 1.6 (4) | C17—C18—C19—C20 | 0.6 (3) |
C4—C3—C8—C7 | −0.3 (4) | C18—C19—C20—C15 | −0.1 (3) |
C2—C3—C8—C7 | 177.6 (3) | C18—C19—C20—C11 | −179.8 (2) |
C2—N1—C9—C11 | −118.0 (2) | C14—C15—C20—C19 | 178.3 (2) |
C2—N1—C9—C10 | 121.9 (2) | C16—C15—C20—C19 | −0.5 (3) |
N1—C9—C11—C12 | −25.3 (3) | C14—C15—C20—C11 | −2.0 (3) |
C10—C9—C11—C12 | 93.4 (2) | C16—C15—C20—C11 | 179.16 (18) |
N1—C9—C11—C20 | 157.71 (17) | C12—C11—C20—C19 | −179.5 (2) |
C10—C9—C11—C20 | −83.6 (2) | C9—C11—C20—C19 | −2.5 (3) |
C20—C11—C12—C13 | 1.1 (3) | C12—C11—C20—C15 | 0.8 (3) |
C9—C11—C12—C13 | −175.92 (19) | C9—C11—C20—C15 | 177.88 (17) |
Experimental details
Crystal data | |
Chemical formula | C19H17N |
Mr | 259.34 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 298 |
a, b, c (Å) | 8.0761 (8), 7.7874 (8), 11.7760 (11) |
β (°) | 95.033 (7) |
V (Å3) | 737.76 (13) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.4 × 0.2 × 0.2 |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2470, 1595, 1276 |
Rint | 0.017 |
(sin θ/λ)max (Å−1) | 0.621 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.094, 1.02 |
No. of reflections | 1595 |
No. of parameters | 183 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.09, −0.08 |
Absolute structure | 223 Friedel pairs merged |
Computer programs: XSCANS (Siemens, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2006).
Acknowledgements
Support from VIEP-UAP (GUPJ-NAT10-G) is acknowledged.
References
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Schiff base compounds are widely studied and used, attracting much attention in both organic synthesis and metal ion complexation. Recently, we have focused our attention on the synthesis of chiral and achiral Schiff bases (Espinosa Leija et al., 2009; Bernès et al., 2010). In continuation of this work, we synthesized the title compound using the solvent-free approach (Tanaka & Toda, 2000). The reaction occurs under mild conditions and requires easier workup procedures and simpler equipment, compared to similar reactions carried out in solution, for example - in refluxing CH2Cl2 (Lee & Ahn, 2002).
In the title molecule (Fig. 1), all distances and bond angles have expected values. The imine group has a sterically favored E conformation, and it is rotated by 23.0 (2)° relative to the phenyl group (the dihedral angle between planes of N1/C2/C9 and C3···C8 groups). The dihedral angle between aromatic phenyl and naphthyl groups is 70.7 (1)°. This molecular conformation is significantly different from one observed in the solid-state for a related imine bearing a thiophene group instead of the phenyl (Espinosa Leija et al., 2009), in which corresponding angles are 5.1 (8) and 83.79 (13)°.
Interestingly, there is a study on conformational flexibility of the title compound that has been published on the basis of DFT calculations at B3LYP/6–31 G(d) level (Fukuda et al., 2007). The potential energies for internal rotations around σ bonds C9*—C11 (ϕ1), C9*—N1 (ϕ2) and C2—C3 (ϕ3) were computed (see Fig. 1 for the angle notations, hereafter assumed for the S enantiomer). The dihedral angle ϕ1 related to the orientation of the naphthyl group has two energy minima, with the global minimum at ϕ1 = 40°, close to that found by X-ray diffraction (ϕ1 = N1—C9—C11—C12 = -25.3 (3)°). Similarly, the orientations for the phenyl ring are consistent between DFT and X-ray data: ϕ3 = 0° vs. ϕ3 = N1—C2—C3—C8 = 19.9 (4)°. In contrast, internal rotation ϕ2 computed by DFT presents a minimum at ϕ2 = 0°, far different from the angle observed in the crystal structure: ϕ2 = C2—N1—C9—C11 = -118.0 (2)°. However, on the ϕ2 potential curve published by Fukuda et al., there are two lesser minima, at ϕ2 = -120° and ϕ2 = 110°. The first one is consistent with the conformer observed in the solid-state (ϕ2 = -118°) and is placed only 2 kcal/mol above the ϕ2 = 0° minimum. It may thus be expected that the title molecule could be crystallized in different polymorphic phases, derived from conformers with different values for the angle ϕ2.