N-Benzyl­formamide at 150 K

The title compound, C₈H₉NO, crystallizes with Z' = 2. Each type of independent mol­ecule links into a separate N-H...O hydrogen-bonded chain in the a-axis direction. There are also three weak C-H...O hydrogen bonds, which join the mol­ecules into a two-dimensional sheet parallel to (001). The mol­ecules exhibit the trans conformation of the -NHCHO group and an anti conformation around the (Ph)C-NH(CHO) bond. The formamide group in each of the symmetry-independent mol­ecules is twisted out of the benzyl group plane, forming angles of 75.96 (10) and 65.23 (11)° with this plane. The significance of this study lies in the comparison drawn between the experimental and calculated data of the crystal structure of the title compound and the data of several other derivatives possessing the -CH₂-NH-CO- group. The correlation between the IR spectrum of this compound and the hydrogen-bond energy is also discussed. This mol­ecular system is of particular interest to biochemists because of its preventative function against toxic products of alcohols in human metabolism.

S1. Comment

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 ν_X—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, ν_N—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).

Related literature

For related literature, see: Allen (2002); Bernstein et al. (1990); Chaney et al. (1996); Desiraju & Steiner (1999); Etter et al. (1991); Flakus (1989, 2003); Flakus & Bańczyk (1999); Flakus & Michta (2008); Fukatsu et al. (2004, 2005); Görbitz & Sagstuen (2004); Galabov et al. (2003); Gao et al. (2006); Gibbons & Hurley (2004); Grell et al. (1999); Jadżyn et al. (1986); Kushner (1951); Malawska et al. (2004); Nieger et al. (2001); Robertson et al. (2000); Salas-Coronado, Vasquez-Badillo, Medina-Garcia, Garcia-Colon, Noth, Contreras & Flores-Parra (2001); Schindler et al. (1998); Tang et al. (2006); Vargas et al. (2001); Viossat et al. (1986); Zhu et al. (2003).

S2. Experimental

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.

S3. Refinement

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, U_iso(H) values were taken as 1.2 times U_eq(C,N). Please check changes to text in accordance with data in CIF.

Computing details

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).

Figures

	Fig. 1. The two symmetry-independent molecules of NBFA, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A view along the c axis of the N—H···O hydrogen-bonded chains of NBFA. [Symmetry code: (i) x - 1, y, z.]
	Fig. 3. A view along the a axis showing weak C—H···O hydrogen bonds. [Symmetry codes: (ii) x, y - 1, z; (iii) x - 1, y + 1, z; (iv) - x + 3/2, y + 1/2, - z + 1/2.]
	Fig. 4. A view along the c axis showing the formation of the R3^2(8) and R4^3(12) rings.
	Fig. 5. The IR spectrum of NBFA measured by the KBr pellet technique at room temperature, presented in the νN—H frequency range.

N-Benzylformamide

Crystal data

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) Å^3	0.5 × 0.13 × 0.10 mm
Z = 8

Data collection

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

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.066	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.142	w = 1/[σ^2(Fo^2) + (0.0677P)^2] where P = (Fo^2 + 2Fc^2)/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+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.592 (18)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	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*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
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)

Geometric parameters (Å, º)

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)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O1^i	0.833 (14)	2.079 (15)	2.8913 (14)	164.5 (14)
N2—H2N···O2^i	0.867 (14)	1.990 (14)	2.8370 (14)	165.2 (13)
C8—H8···O2^ii	0.965 (14)	2.554 (14)	3.4831 (16)	161.7 (11)
C16—H16···O1^iii	0.997 (14)	2.547 (14)	3.4601 (16)	152.2 (11)
C14—H14···O1^iv	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.