Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108037578/sk3271sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270108037578/sk3271Isup2.hkl |
CCDC reference: 718140
NBFA was purchased from Sigma–Aldrich and used without further purification. It was dissolved in an acetone–petroleum ether mixture (1:1 v/v). After several, days colorless single crystals of NBFA had formed, which proved to be suitable for single-crystal X-ray diffraction analyses.
The aromatic and methylene H atoms were treated as riding on their parent atoms, with C—H = 0.95 and 0.99 Å, respectively. H atoms involved in hydrogen bonding were located in a difference Fourier map and refined freely (refined bond lengths are given in Table 1). For all atoms, Uiso(H) values were taken as 1.2 times Ueq(C,N). Please check changes to text in accordance with data in CIF.
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003) and Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2008).
C8H9NO | F(000) = 576 |
Mr = 135.16 | Dx = 1.245 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 5171 reflections |
a = 4.7069 (9) Å | θ = 2.5–34.5° |
b = 16.036 (3) Å | µ = 0.08 mm−1 |
c = 19.104 (4) Å | T = 150 K |
β = 91.08 (3)° | Polyhedron, colorless |
V = 1441.7 (5) Å3 | 0.5 × 0.13 × 0.10 mm |
Z = 8 |
Oxford Diffraction KM-4 diffractometer with Sapphire3 CCD detector | 3204 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.062 |
Graphite monochromator | θmax = 34.6°, θmin = 2.5° |
ω–scan | h = −7→4 |
16700 measured reflections | k = −25→25 |
5660 independent reflections | l = −30→30 |
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)] = 0.066 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.142 | w = 1/[σ2(Fo2) + (0.0677P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.00 | (Δ/σ)max < 0.001 |
5660 reflections | Δρmax = 0.39 e Å−3 |
197 parameters | Δρmin = −0.51 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.592 (18) |
C8H9NO | V = 1441.7 (5) Å3 |
Mr = 135.16 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 4.7069 (9) Å | µ = 0.08 mm−1 |
b = 16.036 (3) Å | T = 150 K |
c = 19.104 (4) Å | 0.5 × 0.13 × 0.10 mm |
β = 91.08 (3)° |
Oxford Diffraction KM-4 diffractometer with Sapphire3 CCD detector | 3204 reflections with I > 2σ(I) |
16700 measured reflections | Rint = 0.062 |
5660 independent reflections |
R[F2 > 2σ(F2)] = 0.066 | 0 restraints |
wR(F2) = 0.142 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.00 | Δρmax = 0.39 e Å−3 |
5660 reflections | Δρmin = −0.51 e Å−3 |
197 parameters |
Experimental. The crystals were mounted on a quartz glass capillary and cooled to 150?K by a cold dry nitrogen gas stream (Oxford Cryosystems); the temperature stability was ?0.1?K. The IR spectrum of a polycrystalline sample of NBFA was measured in transmission at room temperature using the KBr pellet technique on a Nicolet Magna 560?FT–IR spectrometer and with 4 cm-1 resolution. |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 1.17193 (17) | −0.04055 (6) | 0.12729 (5) | 0.0297 (2) | |
N1 | 0.7426 (2) | 0.01676 (6) | 0.10117 (6) | 0.0256 (2) | |
H1N | 0.569 (3) | 0.0088 (9) | 0.1050 (8) | 0.031* | |
C1 | 0.6363 (2) | 0.15816 (7) | 0.06025 (7) | 0.0246 (3) | |
C2 | 0.5426 (3) | 0.19986 (9) | 0.11924 (7) | 0.0300 (3) | |
H2 | 0.6189 | 0.1856 | 0.1641 | 0.036* | |
C3 | 0.3399 (3) | 0.26182 (8) | 0.11342 (7) | 0.0322 (3) | |
H3 | 0.2772 | 0.2899 | 0.1541 | 0.039* | |
C4 | 0.2277 (3) | 0.28311 (8) | 0.04818 (8) | 0.0321 (3) | |
H4 | 0.0869 | 0.3254 | 0.0442 | 0.039* | |
C5 | 0.3211 (3) | 0.24267 (9) | −0.01102 (7) | 0.0333 (3) | |
H5 | 0.2464 | 0.2575 | −0.0558 | 0.040* | |
C6 | 0.5245 (3) | 0.18026 (8) | −0.00476 (7) | 0.0283 (3) | |
H6 | 0.5877 | 0.1524 | −0.0455 | 0.034* | |
C7 | 0.8562 (2) | 0.09009 (8) | 0.06634 (8) | 0.0314 (3) | |
H7A | 0.9197 | 0.0744 | 0.0190 | 0.038* | |
H7B | 1.0233 | 0.1111 | 0.0932 | 0.038* | |
C8 | 0.9099 (2) | −0.04186 (8) | 0.12819 (6) | 0.0242 (3) | |
H8 | 0.806 (3) | −0.0864 (9) | 0.1501 (7) | 0.029* | |
O2 | 0.67865 (18) | 0.77104 (6) | 0.20013 (5) | 0.0349 (2) | |
N2 | 0.2438 (2) | 0.70949 (6) | 0.20255 (6) | 0.0249 (2) | |
H2N | 0.062 (3) | 0.7189 (9) | 0.2017 (7) | 0.030* | |
C9 | 0.1275 (2) | 0.56527 (7) | 0.17336 (7) | 0.0234 (3) | |
C10 | 0.0304 (3) | 0.58052 (8) | 0.10517 (7) | 0.0282 (3) | |
H10 | 0.1021 | 0.6268 | 0.0800 | 0.034* | |
C11 | −0.1699 (3) | 0.52861 (9) | 0.07388 (7) | 0.0325 (3) | |
H11 | −0.2373 | 0.5400 | 0.0277 | 0.039* | |
C12 | −0.2722 (3) | 0.46023 (9) | 0.10963 (8) | 0.0337 (3) | |
H12 | −0.4098 | 0.4247 | 0.0881 | 0.040* | |
C13 | −0.1736 (3) | 0.44377 (8) | 0.17680 (8) | 0.0329 (3) | |
H13 | −0.2411 | 0.3963 | 0.2012 | 0.040* | |
C14 | 0.0238 (3) | 0.49641 (8) | 0.20867 (7) | 0.0284 (3) | |
H14 | 0.084 (3) | 0.4841 (9) | 0.2567 (8) | 0.034* | |
C15 | 0.3406 (2) | 0.62304 (8) | 0.20782 (7) | 0.0292 (3) | |
H15A | 0.3661 | 0.6076 | 0.2577 | 0.035* | |
H15B | 0.5263 | 0.6173 | 0.1849 | 0.035* | |
C16 | 0.4174 (2) | 0.77412 (8) | 0.19875 (7) | 0.0254 (3) | |
H16 | 0.313 (3) | 0.8279 (9) | 0.1942 (7) | 0.030* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0207 (4) | 0.0313 (5) | 0.0371 (5) | −0.0001 (3) | −0.0008 (3) | 0.0058 (4) |
N1 | 0.0166 (4) | 0.0245 (5) | 0.0357 (6) | −0.0022 (4) | 0.0015 (4) | 0.0050 (4) |
C1 | 0.0211 (5) | 0.0221 (6) | 0.0305 (7) | −0.0027 (4) | 0.0017 (4) | 0.0038 (5) |
C2 | 0.0302 (6) | 0.0323 (7) | 0.0273 (6) | −0.0031 (5) | −0.0009 (5) | 0.0038 (5) |
C3 | 0.0391 (7) | 0.0258 (6) | 0.0321 (7) | −0.0010 (5) | 0.0077 (6) | −0.0033 (5) |
C4 | 0.0343 (7) | 0.0228 (6) | 0.0393 (8) | 0.0044 (5) | 0.0042 (6) | 0.0039 (5) |
C5 | 0.0348 (7) | 0.0336 (7) | 0.0312 (7) | 0.0042 (6) | −0.0022 (5) | 0.0051 (6) |
C6 | 0.0301 (6) | 0.0267 (6) | 0.0282 (7) | 0.0005 (5) | 0.0025 (5) | −0.0010 (5) |
C7 | 0.0236 (6) | 0.0296 (7) | 0.0412 (8) | 0.0013 (5) | 0.0059 (5) | 0.0121 (6) |
C8 | 0.0234 (5) | 0.0230 (6) | 0.0261 (6) | −0.0017 (5) | 0.0016 (4) | 0.0020 (5) |
O2 | 0.0226 (4) | 0.0294 (5) | 0.0527 (6) | −0.0007 (4) | 0.0018 (4) | −0.0010 (4) |
N2 | 0.0182 (4) | 0.0237 (5) | 0.0328 (6) | 0.0027 (4) | 0.0002 (4) | −0.0018 (4) |
C9 | 0.0217 (5) | 0.0204 (6) | 0.0281 (6) | 0.0037 (4) | 0.0009 (4) | 0.0008 (5) |
C10 | 0.0301 (6) | 0.0258 (6) | 0.0286 (7) | 0.0008 (5) | 0.0017 (5) | 0.0036 (5) |
C11 | 0.0380 (7) | 0.0324 (7) | 0.0269 (6) | 0.0017 (6) | −0.0041 (5) | −0.0015 (5) |
C12 | 0.0332 (7) | 0.0257 (7) | 0.0420 (8) | −0.0015 (5) | −0.0049 (6) | −0.0053 (6) |
C13 | 0.0330 (6) | 0.0227 (6) | 0.0432 (8) | −0.0020 (5) | 0.0015 (6) | 0.0071 (6) |
C14 | 0.0284 (6) | 0.0276 (6) | 0.0291 (7) | 0.0031 (5) | −0.0008 (5) | 0.0054 (5) |
C15 | 0.0252 (6) | 0.0238 (6) | 0.0384 (7) | 0.0024 (5) | −0.0059 (5) | 0.0021 (5) |
C16 | 0.0251 (6) | 0.0231 (6) | 0.0281 (6) | 0.0037 (5) | 0.0005 (5) | −0.0013 (5) |
O1—C8 | 1.2338 (14) | O2—C16 | 1.2303 (14) |
N1—C8 | 1.3248 (15) | N2—C16 | 1.3226 (16) |
N1—C7 | 1.4577 (16) | N2—C15 | 1.4619 (16) |
N1—H1N | 0.833 (14) | N2—H2N | 0.867 (14) |
C1—C6 | 1.3856 (18) | C9—C14 | 1.3874 (18) |
C1—C2 | 1.3894 (19) | C9—C10 | 1.3941 (18) |
C1—C7 | 1.5071 (17) | C9—C15 | 1.5073 (17) |
C2—C3 | 1.3807 (19) | C10—C11 | 1.3847 (18) |
C2—H2 | 0.9500 | C10—H10 | 0.9500 |
C3—C4 | 1.387 (2) | C11—C12 | 1.383 (2) |
C3—H3 | 0.9500 | C11—H11 | 0.9500 |
C4—C5 | 1.383 (2) | C12—C13 | 1.382 (2) |
C4—H4 | 0.9500 | C12—H12 | 0.9500 |
C5—C6 | 1.3885 (18) | C13—C14 | 1.3876 (19) |
C5—H5 | 0.9500 | C13—H13 | 0.9500 |
C6—H6 | 0.9500 | C14—H14 | 0.976 (16) |
C7—H7A | 0.9900 | C15—H15A | 0.9900 |
C7—H7B | 0.9900 | C15—H15B | 0.9900 |
C8—H8 | 0.965 (14) | C16—H16 | 0.997 (14) |
C8—N1—C7 | 122.00 (10) | C16—N2—C15 | 123.70 (10) |
C8—N1—H1N | 115.8 (10) | C16—N2—H2N | 118.2 (10) |
C7—N1—H1N | 122.2 (10) | C15—N2—H2N | 118.1 (10) |
C6—C1—C2 | 118.88 (11) | C14—C9—C10 | 118.79 (11) |
C6—C1—C7 | 120.20 (12) | C14—C9—C15 | 120.94 (11) |
C2—C1—C7 | 120.92 (12) | C10—C9—C15 | 120.26 (11) |
C3—C2—C1 | 120.69 (12) | C11—C10—C9 | 120.43 (12) |
C3—C2—H2 | 119.7 | C11—C10—H10 | 119.8 |
C1—C2—H2 | 119.7 | C9—C10—H10 | 119.8 |
C2—C3—C4 | 120.02 (13) | C12—C11—C10 | 120.26 (13) |
C2—C3—H3 | 120.0 | C12—C11—H11 | 119.9 |
C4—C3—H3 | 120.0 | C10—C11—H11 | 119.9 |
C5—C4—C3 | 119.86 (12) | C13—C12—C11 | 119.74 (12) |
C5—C4—H4 | 120.1 | C13—C12—H12 | 120.1 |
C3—C4—H4 | 120.1 | C11—C12—H12 | 120.1 |
C4—C5—C6 | 119.81 (13) | C12—C13—C14 | 120.11 (12) |
C4—C5—H5 | 120.1 | C12—C13—H13 | 119.9 |
C6—C5—H5 | 120.1 | C14—C13—H13 | 119.9 |
C1—C6—C5 | 120.73 (12) | C13—C14—C9 | 120.65 (12) |
C1—C6—H6 | 119.6 | C13—C14—H14 | 118.0 (9) |
C5—C6—H6 | 119.6 | C9—C14—H14 | 121.3 (9) |
N1—C7—C1 | 111.24 (10) | N2—C15—C9 | 110.43 (10) |
N1—C7—H7A | 109.4 | N2—C15—H15A | 109.6 |
C1—C7—H7A | 109.4 | C9—C15—H15A | 109.6 |
N1—C7—H7B | 109.4 | N2—C15—H15B | 109.6 |
C1—C7—H7B | 109.4 | C9—C15—H15B | 109.6 |
H7A—C7—H7B | 108.0 | H15A—C15—H15B | 108.1 |
O1—C8—N1 | 124.71 (11) | O2—C16—N2 | 125.85 (12) |
O1—C8—H8 | 122.2 (8) | O2—C16—H16 | 121.9 (8) |
N1—C8—H8 | 113.1 (8) | N2—C16—H16 | 112.3 (8) |
C6—C1—C2—C3 | 0.53 (18) | C14—C9—C10—C11 | 1.16 (18) |
C7—C1—C2—C3 | −179.59 (11) | C15—C9—C10—C11 | −178.60 (12) |
C1—C2—C3—C4 | −0.07 (19) | C9—C10—C11—C12 | −1.1 (2) |
C2—C3—C4—C5 | −0.6 (2) | C10—C11—C12—C13 | −0.1 (2) |
C3—C4—C5—C6 | 0.7 (2) | C11—C12—C13—C14 | 1.1 (2) |
C2—C1—C6—C5 | −0.36 (18) | C12—C13—C14—C9 | −0.9 (2) |
C7—C1—C6—C5 | 179.77 (11) | C10—C9—C14—C13 | −0.17 (18) |
C4—C5—C6—C1 | −0.3 (2) | C15—C9—C14—C13 | 179.59 (12) |
C8—N1—C7—C1 | −162.61 (12) | C16—N2—C15—C9 | −149.33 (12) |
C6—C1—C7—N1 | −111.62 (13) | C14—C9—C15—N2 | −128.16 (12) |
C2—C1—C7—N1 | 68.50 (15) | C10—C9—C15—N2 | 51.60 (15) |
C7—N1—C8—O1 | 0.5 (2) | C15—N2—C16—O2 | −1.2 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.833 (14) | 2.079 (15) | 2.8913 (14) | 164.5 (14) |
N2—H2N···O2i | 0.867 (14) | 1.990 (14) | 2.8370 (14) | 165.2 (13) |
C8—H8···O2ii | 0.965 (14) | 2.554 (14) | 3.4831 (16) | 161.7 (11) |
C16—H16···O1iii | 0.997 (14) | 2.547 (14) | 3.4601 (16) | 152.2 (11) |
C14—H14···O1iv | 0.976 (16) | 2.508 (16) | 3.4718 (18) | 169.4 (11) |
Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) x−1, y+1, z; (iv) −x+3/2, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C8H9NO |
Mr | 135.16 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 150 |
a, b, c (Å) | 4.7069 (9), 16.036 (3), 19.104 (4) |
β (°) | 91.08 (3) |
V (Å3) | 1441.7 (5) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.5 × 0.13 × 0.10 |
Data collection | |
Diffractometer | Oxford Diffraction KM-4 diffractometer with Sapphire3 CCD detector |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16700, 5660, 3204 |
Rint | 0.062 |
(sin θ/λ)max (Å−1) | 0.798 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.066, 0.142, 1.00 |
No. of reflections | 5660 |
No. of parameters | 197 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.39, −0.51 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2003) and Mercury (Macrae et al., 2006), publCIF (Westrip, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.833 (14) | 2.079 (15) | 2.8913 (14) | 164.5 (14) |
N2—H2N···O2i | 0.867 (14) | 1.990 (14) | 2.8370 (14) | 165.2 (13) |
C8—H8···O2ii | 0.965 (14) | 2.554 (14) | 3.4831 (16) | 161.7 (11) |
C16—H16···O1iii | 0.997 (14) | 2.547 (14) | 3.4601 (16) | 152.2 (11) |
C14—H14···O1iv | 0.976 (16) | 2.508 (16) | 3.4718 (18) | 169.4 (11) |
Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) x−1, y+1, z; (iv) −x+3/2, y+1/2, −z+1/2. |
Monosubstituted formamides are good inhibitors of class I (α, β and γ) and class II (π) human alcohol dehydrogenase (HsADH; Schindler et al., 1998). N-benzylamides have anticonvulsant functions (Kushner et al., 1951; Malawska et al., 2004). The title compound, (I), is the simplest N-benzylamide and thus its biological function has attracted considerable interest in recent years. N-benzylformamide (NBFA) is a selective inhibitor for the HsADH β1 enzyme (Schindler et al. 1998). The structure of the HsADH β(1)β(1) isoform complexed with NBFA was determined by X-ray methods with 1.6 Å resolution (Gibbons & Hurley, 2004). The novel enzyme N-substituted formamide deformylase (NfdA) was discovered in the microorganism Arthrobacter pascens F164, which was able to grow on NBFA as a sole nitrogen source (Fukatsu et al., 2005). The gene (NfdA) encoding this enzyme was also cloned (Fukatsu et al., 2004). NBFA is of great importance for the reduction with NaBH4 to benzylmethylamine (Zhu et al., 2003). The conformational analysis of NBFA was performed with the help of density functional theory and second-order Møller-Plesset (MP2) calculations (Vargas et al., 2001; Robertson et al., 2000). The dielectric properties and the self-association process of NBFA solutions in carbon tetrachloride have been studied on the basis of IR spectroscopy (Jadżyn et al., 1986).
The objects of our research are the IR spectra of the secondary amide crystals in a frequency range of the proton and deuteron stretching vibrations in the hydrogen bond (Flakus & Michta, 2008). Characteristic isotopic and spectroscopic effects, called the self-organization effect, are observed in this vibration frequency range (Flakus, 1989, 2003; Flakus & Bańczyk, 1999). Measurements of the polarized IR spectra of spatially oriented diverse hydrogen-bond systems present in the lattices of molecular crystals allow us to estimate the polarization properties of transitions found in the excited states of the proton vibrations in the crystals, which contribute to the νX—H band generation mechanisms in the crystalline spectra. Thus, for the reliable interpretation of the self-organization mechanism, the crystal structure of the hydrogen-bond system must be known. In the case of NBFA, a crystallographic study has not been reported yet.
In this article the result of our structural studies of the hydrogen bonds of NBFA is presented. NBFA crystallizes with two molecules in the asymmetric unit (Fig. 1). Both molecules, with comparable bond lengths and angles, adopt the trans conformation of the –NH—CO–, group with deviations from planarity smaller than 1°, and the anti conformation around the (Ph)C—N(CHO) bond (the syn conformation of the PhC—NH group). The trans arrangement of the NH—CO group is more frequently found in nature than the cis form (Galabov et al., 2003). The calculated energy for the cis form of NBFA is about 7.6 kJ mol-1 higher than that calculated for the trans isomer (Robertson et al., 2000). Thus the trans conformation of the NH—CO group is more stable than the cis one.
The formamide group is twisted out of the benzyl group plane, and the angle between this plane and the amide group plane is 75.96 (10) and 65.23 (11)° for the symmetry-independent molecules containing atoms N1 and N2, respectively. The largest deviations from the least-squares benzene plane are observed for atoms C2 (C10) and C4 (C12), and the deviations are in the range 0.0047–0.0124 Å. The C(H2)—N and C═O bond lengths are in the region of 1.460 and 1.232 Å, respectively, and compare well with those of related compounds, such as butanediyl diformamide (Chaney et al., 1996), N,N'-dibenzyloxalamide (Nieger et al., 2001) or (R)-N-benzylmandelamide (Salas-Coronado et al., 2001). These bond lengths are also in good agreement with those calculated by the MP2/DZP and MM3 methods (Vargas et al., 2001). The length of the N—C(═O) bond is slightly shorter (1.324 Å) than the calculated value but is in good agreement with those of related compounds, such as (R)-N-benzylmandelamide (Salas-Coronado et al., 2001), N-formylglycine (Görbitz & Sagstuen, 2004) or 1-formylamino-2-(2-hydroxyphenyl)-1-phenylethylene (Viossat et al., 1986). The main differences between the calculated and the experimental values are observed for two dihedral angles: C2—C1—C7—N1 (C10—C9—C15—N2) and C1—C7—N1—C8 (C9—C15—N2—C16). For N1-containing molecule the experimental angles are 68.50 (15) and -162.61 (12)°, respectively, and for the other molecule they are 51.60 (15) and -149.33 (12)°. The values of these angles calculated by the MP2/DZP method were 106.4 and -83.4° (Vargas et al., 2001) and by the MP2/6–31G** method were 71 and -92° (Robertson et al., 2000). These dihedral anglescan adopt significantly different values in related compounds, such as N-{[3'-formyl-2,2'-bis(methoxymethoxy)biphenyl-3-yl]methyl}formamide (76.46 and -105.78°; Gao et al., 2006) or N-acetylbenzamide (21.79 and -166.23°; Etter et al., 1991).
For comparison of the lengths and angles with other N-benzylformamide derivatives, a search of the Cambridge Structural Database [CSD, Version 5.28 (Allen, 2002); ConQuest, Version 1.9 (Bruno et al., 2002)] yielded two structures: N-{[3'-formyl-2,2'-bis(methoxymethoxy)biphenyl-3-yl]methyl}formamide (Gao et al., 2006) and catena-[(µ3-4-{N-formyl-N-[methylene(phosphonato)]αmmoniomethyl}benzoate)-(µ2–4-{N-formyl-N-[methylene(hydrogenphosphonato)]\ ammoniomethyl}benzoate)-αquaerbium(III)] (Tang et al., 2006). The comparison of the angles and bond lengths with the corresponding values of NBFA is very hard, because there are so many substitutents in both structures and these groups have a strong influence on the geometric parameters.
In the crystal structure of NBFA the two symmetry-independent molecules interact via N—H···O hydrogen bonds (Table 1), forming two separate infinite zigzag chains parallel to the a axis with graph-set notation C11(4) (Fig. 2; Bernstein et al., 1990; Grell et al., 1999). There are also three weak C—H···O hydrogen bonds (Table 1) with graph-set notation D11(2) (Bernstein et al., 1990; Grell et al., 1999). These bonds join the molecules into a two-dimensional network parallel to (001) (Fig. 3). The second-level graph-set notation gives of about 17 possible arrangements of the hydrogen-bond rings, for example R32(8) and R43(12) (Fig. 4; Bernstein et al., 1990; Grell et al., 1999).
The values of the N—H···O hydrogen-bond distances are in the range 2.5–3.2 Å and therefore they can be treated as strong hydrogen bonds (Desiraju & Steiner, 1999). The strength of the hydrogen bonds in this compound was also investigated with IR spectroscopy. The band of the isolated N—H stretching vibration, νN—H, is located at a frequency of 3400 cm-1. In the case of NBFA we observed the band of the N—H stretching vibration in the frequency range 3350–2800 cm-1, with a shift of about 300 cm-1 (Fig. 5). This relative shift is larger than 5% and this value is characteristic for a strong hydrogen bond (Desiraju & Steiner, 1999).