Non-mutagenic organic pigment intermediates. II. Isomorphous 2,2′-di­chloro-5,5′-dipropoxy­benzidine and 2,2′-di­methyl-5,5′-dipropoxy­benzidine

The title compounds, C₁₈H₂₂Cl₂N₂O₂ and C₂₀H₂₈N₂O₂, respectively, are isomorphous. The mol­ecules lie at general positions in the unit cell. In each structure, chemically equivalent but crystallographically inequivalent amine N atoms exhibit different degrees of pyramidalization. The structures exhibit weak N—H...N hydrogen bonding, which is influenced by the differences in hybridization around the amine N atoms. The torsion angles across the bi­phenyl linkage for the two compounds are 67.2 (2) and 68.3 (3)°.

S1. Comment

Colorants based on non-mutagenic highly twisted benzidine congeners are expected to be more soluble in organic solvents than the planar derivatives, and produce different color gamuts (Hinks et al., 2000, 2001; Sokolowska et al., 2001). The variety of colors obtained is due to varying degrees of delocalization in the conjugated π system and can be of considerable commercial importance. We have previously reported the structure of 3,3'-dipropoxybenzidene (El-Shafei et al., 2003), which has a negligible twist about the biphenyl linkage. We undertook the X-ray structural investigation of two 2,2'-substituted dipropoxybenzidines to investigate the structural changes induced by the steric hindrance caused by the substituted ortho positions. In this paper, we report the structures of two isomorphous 2,2'-substituted benzidines, 2,2'-dichloro-5,5'-dipropoxybenzidine, (I), and 2,2'-dimethyl-5,5'-dipropoxybenzidine, (II). \sch

Views of (I) and (II), with their atom-labelling schemes, are shown in Figs. 1 and 2, respectively. Selected bond lengths and angles are shown in Tables 1 and 2. The molecules lie on general positions in the unit cell. As expected, both diamines show appreciable twist across the biphenyl linkage. The C2—C1—C1'-C2' torsion angles are 67.2 (2)° in (I) and 68.3 (3)° in (II). According to the rules stated by Kitaigorodskii (1965, 1973), chloro-methyl exchange does not change the crystal structure, since the two substituents have nearly the same volume (Cl 20 and Me 24 ų). As this exchange rule appears to be active in the structures of (I) and (II), it is not surprising that the values of the torsion angles across the biphenyl linkage are similar. In addition, because (I) and (II) are isomorphous, the `chloro effect' cannot be considered an important packing interaction in (I). It is interesting to note, however, that 2,2'-dichlorobenzidine (Smare, 1948) and 2,2'-dimethylbenzidine (Fowweather, 1952) are not isomorphous, crystallize with different site symmetries and have appreciably different torsion angles across the biphenyl linkage.

In (I), the C4—N1 bond is significantly shorter than the C4'-N1' bond and this is consistent with delocalization of the lone pair on N1 into the aromatic π system. The same numeric trend is observed in (II), but the greater standard uncertainties associated with those bond lengths preclude making a definitive statement. It is interesting to note that the difference in hybridization between atoms N1 and N1' is also manifest in their respective hydrogen-bonding properties (see below).

The structures of (I) and (II) show a number of intra- and intermolecular hydrogen bonds. These have been tabulated on Tables 2 and 4, respectively, where the geometries are based on N—H bond lengths which have been normalized to 1.01 Å. *FOOTNOTE[The normalized N—H length was obtained by searching the Cambridge Structural Database (Allen, 2002) for structures obtained by single-crystal neutron diffraction at 100 K or lower of compounds containing aryl-bound amino groups, and taking the mean of the N—H lengths.]*ENDFOOTNOTE As with the structure of 3,3'-dipropoxybenzidine, the present two structures show intramolecular hydrogen bonds between the n-propoxyl O atom and one of the amino H atoms. Unlike the structure of 3,3'-dipropoxybenzidine, these structures show no N—H···π interactions. However, (I) and (II) show a number of long-range intermolecular interactions involving the amino H atoms and N acceptor atoms. The individual N—H···N motifs form an R₄²(8) ring, which lies across a crystallographic centre of symmetry (Fig. 3). The R₄²(8) pattern acts as a linkage between molecules, which form an extended two-dimensional network parallel to (101).

A structural correlation study (Allen et al., 1995) has indicated that N—H···N contacts with H···N ≤ 2.75 Å, which have χ_N ≥ 35° and the N—H···N donor angle > 130°, can be considered true hydrogen bonds. These criteria were used to assess the long-range N—H···N interactions in (I) and (II). The values of χ_N and τ for (I) and (II), as well as those for 3,3'-dipropoxybenzidene, are listed in Table 5. As can be seen from Table 5, the N—H···N interactions for (I) and (II) fulfill these criteria. The more highly pyramidalized amino groups (N1') act as hydrogen-bond acceptors, whereas the less pyramidal amino groups (N1) act as hydrogen-bond donors. Both H atoms on N1 participate in the hydrogen bonding. This is an interesting instance where chemically equivalent amino groups differ in their degree of pyramidalization and adopt different crystallographic functions in the structure.

Finally, it is worth pointing out that the structures of (I) and (II), as well as that of 3,3'-dipropoxybenzidine, highlight the competition between N—H···π and long-range (weak) N—H···N hydrogen bonds. Slight changes in the pyramidalization of the N atoms, as evidenced in the χ_N values, lead to completely different types of intermolecular hydrogen-bonding interactions. The χ_N values listed in Table 5 vary from a minimum of 36.4° in 3,3'-dipropoxybenzidine to a maximum of 53.4° in (II). The N atoms in 3,3'-dipropoxybenzidine are ineffective as hydrogen-bond acceptors, due to their relatively small degree of pyramidalization, and consequently the N—H donors use the aromatic π clouds as acceptors. In contrast, the more highly pyramidalized N atoms in (I) and (II) make marginally acceptable hydrogen-bond acceptors, and the crystal packing takes advantage of this greater basicity.

S2. Experimental

Benzidine analogs (I) and (II) were prepared as previously reported by Hinks et al. (2000). Suitable single crystals were produced by dissolving (I) (0.45 g) in ethanol (40 ml) and (II) (0.4 g) in methanol (40 ml), stirring at the boiling point for 2 min, filtering while hot into an Erlenmeyer flask, and covering the flask opening with perforated Parafilm. The filtrates were then allowed to cool slowly and stand undisturbed for 5 d.

S3. Refinement

Please give brief details of the H-atom treatment for (II).

Computing details

For both compounds, data collection: CAD-4 ARGUS (Enraf-Nonius, 1994); cell refinement: CAD-4 ARGUS; data reduction: DATRD2 in NRCVAX (Gabe et al., 1989); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: LSTSQ in NRCVAX; molecular graphics: NRCVAX and ORTEPII (Johnson, 1976; software used to prepare material for publication: TABLES in NRCVAX (January 1994 version).

Figures

	Fig. 1. A drawing of the structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A drawing of the structure of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 3. A diagram of the hydrogen-bonding pattern in (I). Displacement ellipsoids are drawn at the 50% probability level. H atoms bound to C atoms have been omitted for clarity, and the remaining H atoms are shown as small spheres of arbitrary radii [symmetry codes: (i) x, y, z; (ii) 1 − x, −y, 1 − z; (iii) 3/2 − x, −1/2 + y, 3/2 − z; (iv) −1/2 + x, 1/2 − y, −1/2 + z].

(I) 2,2'-dichloro-5,5'-dipropoxybenzidine

Crystal data

C18H22Cl2N2O2	? #Insert any comments here.
Mr = 369.29	Dx = 1.391 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.3054 (4) Å	Cell parameters from 25 reflections
b = 22.7966 (11) Å	θ = 17.0–18.0°
c = 10.5956 (8) Å	µ = 0.38 mm^−1
β = 91.679 (6)°	T = 148 K
V = 1763.82 (19) Å^3	Prism, off-white
Z = 4	0.42 × 0.34 × 0.22 mm
F(000) = 777.56

Data collection

Enraf-Nonius CAD-4 MACH diffractometer	Rint = 0.035
Radiation source: X-ray tube	θmax = 30.0°, θmin = 1.2°
Graphite monochromator	h = −10→10
ω scan b/P/b	k = 0→31
5099 measured reflections	l = 0→14
5089 independent reflections	3 standard reflections every 80 min
4464 reflections with Inet > σ(Inet)	intensity decay: 2.2%

Refinement

Refinement on F	305 parameters
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.030	Weighting scheme based on measured s.u.'s 1/(σ^2(F) + 0.00007F^2)
wR(F^2) = 0.039	(Δ/σ)max = 0.001
S = 2.56	Δρmax = 0.51 e Å^−3
4461 reflections	Δρmin = −0.27 e Å^−3

Special details

Experimental. The solutions were checked after 3 d to monitor crystal growth. Appropriate single crystals of (I) and (II) were selected for X-ray analysis by examining them under a microscope.

The samples were mounted on the end of a glass fiber using a small amount of silicone grease and transferred to the diffractometer. The sample was maintained at a temperature of 148 K using a nitrogen cold stream. All X-ray measurements were made on an Enraf–Nonius CAD-4 MACH diffractometer. The unit-cell dimensions were determined by a fit of 25 well centered reflections and their Friedel pairs, with an angular range of 32° [for (II)] and 34° [for (I)] < 2θ < 36°. A quadrant of unique data was collected using the ω scan mode in a non-bisecting geometry. The adoption of a non-bisecting scan mode was accomplished by offsetting ψ by 20° for each data point collected. This was done to minimize the interaction of the goniometer head with the cold stream. Three standard reflections were measured every 4800 s of X-ray exposure time. Scaling the data was accomplished using a five-point smoothed curved routine fit to the intensity check reflections. The intensity data were corrected for Lorentz and polarization effects. No absorption correction was made.

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

	x	y	z	Uiso*/Ueq
Cl1	0.31443 (4)	0.260021 (12)	0.47293 (3)	0.01934 (12)
O1	0.91748 (11)	0.09805 (3)	0.60685 (8)	0.0159 (4)
N1	0.64341 (15)	0.06231 (4)	0.44950 (10)	0.0200 (4)
C1	0.63154 (14)	0.23350 (5)	0.60462 (10)	0.0128 (4)
C2	0.49252 (14)	0.21351 (5)	0.52268 (10)	0.0137 (4)
C3	0.49247 (15)	0.15678 (5)	0.47326 (10)	0.0150 (4)
C4	0.63494 (15)	0.11826 (5)	0.50296 (10)	0.0145 (4)
C5	0.77925 (14)	0.13816 (5)	0.58357 (10)	0.0133 (4)
C6	0.77579 (14)	0.19442 (5)	0.63350 (10)	0.0135 (4)
C7	1.08063 (15)	0.12045 (5)	0.67006 (11)	0.0162 (5)
C8	1.22043 (16)	0.07137 (5)	0.67577 (12)	0.0188 (5)
C9	1.37756 (18)	0.08658 (6)	0.76832 (14)	0.0247 (6)
Cl1'	0.34187 (4)	0.273018 (13)	0.79674 (3)	0.01994 (12)
O1'	0.94954 (11)	0.42412 (3)	0.64239 (8)	0.0174 (4)
N1'	0.70820 (15)	0.46582 (4)	0.80441 (10)	0.0191 (4)
C1'	0.64198 (14)	0.29407 (5)	0.65648 (9)	0.0128 (4)
C2'	0.51783 (14)	0.31681 (5)	0.74105 (10)	0.0143 (4)
C3'	0.53438 (15)	0.37404 (5)	0.78799 (10)	0.0154 (4)
C4'	0.67886 (15)	0.40947 (5)	0.75239 (10)	0.0145 (4)
C5'	0.80893 (14)	0.38643 (5)	0.67002 (10)	0.0137 (4)
C6'	0.78946 (15)	0.32989 (5)	0.62312 (10)	0.0140 (4)
C7'	1.10169 (15)	0.39913 (5)	0.57728 (11)	0.0159 (5)
C8'	1.23638 (16)	0.44772 (5)	0.55044 (12)	0.0189 (5)
C9'	1.38405 (17)	0.42501 (6)	0.46307 (12)	0.0217 (5)
H1A	0.698 (2)	0.0364 (8)	0.4960 (16)	0.030 (4)*
H1B	0.542 (2)	0.0504 (7)	0.4111 (16)	0.030 (4)*
H3	0.399 (2)	0.1446 (7)	0.4180 (14)	0.022 (4)*
H6	0.870 (2)	0.2092 (6)	0.6904 (14)	0.017 (3)*
H7A	1.0497 (19)	0.1334 (6)	0.7567 (13)	0.013 (3)*
H7B	1.128 (2)	0.1533 (7)	0.6201 (14)	0.021 (4)*
H8A	1.165 (2)	0.0370 (7)	0.7022 (14)	0.020 (4)*
H8B	1.260 (2)	0.0645 (7)	0.5897 (15)	0.027 (4)*
H9A	1.331 (2)	0.0898 (7)	0.8514 (15)	0.027 (4)*
H9B	1.434 (2)	0.1234 (8)	0.7454 (17)	0.039 (5)*
H9C	1.471 (2)	0.0560 (7)	0.7682 (15)	0.027 (4)*
H1A'	0.761 (2)	0.4879 (8)	0.7517 (17)	0.033 (5)*
H1B'	0.616 (3)	0.4811 (8)	0.8348 (17)	0.033 (4)*
H3'	0.448 (2)	0.3884 (6)	0.8454 (14)	0.019 (4)*
H6'	0.876 (2)	0.3116 (7)	0.5638 (14)	0.021 (4)*
H7A'	1.0532 (19)	0.3809 (6)	0.4951 (13)	0.014 (3)*
H7B'	1.157 (2)	0.3677 (7)	0.6298 (14)	0.020 (4)*
H8A'	1.289 (2)	0.4618 (7)	0.6296 (15)	0.027 (4)*
H8B'	1.171 (2)	0.4798 (7)	0.5100 (14)	0.020 (4)*
H9A'	1.452 (2)	0.3934 (7)	0.5022 (14)	0.024 (4)*
H9B'	1.326 (2)	0.4120 (7)	0.3807 (15)	0.026 (4)*
H9C'	1.475 (2)	0.4539 (8)	0.4414 (17)	0.038 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.01652 (13)	0.01999 (13)	0.02119 (14)	0.00353 (10)	−0.00517 (10)	−0.00112 (10)
O1	0.0125 (4)	0.0129 (4)	0.0220 (4)	0.0005 (3)	−0.0019 (3)	−0.0016 (3)
N1	0.0202 (5)	0.0140 (5)	0.0256 (5)	−0.0016 (4)	−0.0033 (4)	−0.0044 (4)
C1	0.0118 (4)	0.0139 (5)	0.0127 (5)	−0.0009 (4)	0.0023 (3)	−0.0004 (4)
C2	0.0111 (4)	0.0158 (5)	0.0142 (5)	0.0009 (4)	0.0004 (4)	0.0009 (4)
C3	0.0137 (5)	0.0167 (5)	0.0145 (5)	−0.0033 (4)	−0.0001 (4)	−0.0014 (4)
C4	0.0148 (5)	0.0142 (5)	0.0147 (5)	−0.0025 (4)	0.0025 (4)	−0.0012 (4)
C5	0.0112 (4)	0.0138 (5)	0.0149 (5)	−0.0003 (4)	0.0023 (4)	0.0006 (4)
C6	0.0118 (4)	0.0151 (5)	0.0137 (5)	−0.0014 (4)	0.0006 (4)	−0.0012 (4)
C7	0.0127 (5)	0.0156 (5)	0.0202 (5)	−0.0008 (4)	−0.0003 (4)	−0.0008 (4)
C8	0.0150 (5)	0.0165 (5)	0.0249 (6)	0.0017 (4)	0.0000 (4)	0.0011 (4)
C9	0.0167 (5)	0.0277 (6)	0.0296 (6)	0.0008 (5)	−0.0031 (5)	0.0036 (5)
Cl1'	0.01691 (13)	0.02273 (14)	0.02059 (14)	−0.00299 (10)	0.00749 (10)	−0.00160 (10)
O1'	0.0129 (4)	0.0139 (4)	0.0255 (4)	−0.0010 (3)	0.0034 (3)	−0.0025 (3)
N1'	0.0200 (5)	0.0149 (4)	0.0222 (5)	0.0029 (4)	0.0002 (4)	−0.0046 (4)
C1'	0.0115 (4)	0.0143 (5)	0.0126 (4)	0.0009 (4)	−0.0004 (3)	−0.0012 (4)
C2'	0.0114 (4)	0.0175 (5)	0.0141 (5)	0.0004 (4)	0.0015 (4)	0.0004 (4)
C3'	0.0143 (5)	0.0179 (5)	0.0140 (5)	0.0034 (4)	0.0009 (4)	−0.0019 (4)
C4'	0.0144 (5)	0.0148 (5)	0.0140 (4)	0.0032 (4)	−0.0026 (4)	−0.0019 (4)
C5'	0.0108 (4)	0.0142 (5)	0.0161 (5)	0.0010 (4)	−0.0011 (4)	0.0009 (4)
C6'	0.0117 (4)	0.0156 (5)	0.0147 (5)	0.0008 (4)	0.0015 (4)	−0.0015 (4)
C7'	0.0126 (5)	0.0149 (5)	0.0203 (5)	0.0008 (4)	0.0019 (4)	−0.0005 (4)
C8'	0.0166 (5)	0.0161 (5)	0.0241 (6)	−0.0020 (4)	0.0026 (4)	−0.0009 (4)
C9'	0.0185 (5)	0.0207 (6)	0.0263 (6)	−0.0017 (4)	0.0055 (5)	0.0003 (5)

Geometric parameters (Å, º)

Cl1—C2	1.7477 (11)	Cl1'—C2'	1.7441 (11)
O1—C5	1.3792 (13)	O1'—C5'	1.3772 (13)
O1—C7	1.4433 (13)	O1'—C7'	1.4425 (13)
N1—C4	1.3976 (15)	N1'—C4'	1.4117 (15)
N1—H1A	0.860 (18)	N1'—H1A'	0.853 (19)
N1—H1B	0.878 (18)	N1'—H1B'	0.833 (19)
C1—C2	1.3933 (15)	C1'—C2'	1.3935 (15)
C1—C6	1.4066 (15)	C1'—C6'	1.4052 (15)
C1—C1'	1.4874 (15)	C2'—C3'	1.4002 (16)
C2—C3	1.3954 (15)	C3'—C4'	1.3899 (16)
C3—C4	1.3908 (16)	C3'—H3'	0.949 (15)
C3—H3	0.928 (16)	C4'—C5'	1.4104 (15)
C4—C5	1.4120 (15)	C5'—C6'	1.3872 (15)
C5—C6	1.3880 (15)	C6'—H6'	0.996 (15)
C6—H6	0.964 (15)	C7'—C8'	1.5141 (16)
C7—C8	1.5148 (16)	C7'—H7A'	1.019 (14)
C7—H7A	0.997 (14)	C7'—H7B'	0.986 (15)
C7—H7B	0.987 (15)	C8'—C9'	1.5320 (17)
C8—C9	1.5276 (18)	C8'—H8A'	0.966 (16)
C8—H8A	0.930 (16)	C8'—H8B'	0.965 (15)
C8—H8B	0.979 (16)	C9'—H9A'	0.963 (16)
C9—H9A	0.955 (17)	C9'—H9B'	1.005 (16)
C9—H9B	0.969 (19)	C9'—H9C'	0.967 (18)
C9—H9C	0.974 (17)
C5—O1—C7	116.03 (8)	C5'—O1'—C7'	116.44 (8)
C4—N1—H1A	114.8 (11)	C4'—N1'—H1A'	110.4 (12)
C4—N1—H1B	115.1 (11)	C4'—N1'—H1B'	114.6 (12)
H1A—N1—H1B	115.1 (16)	H1A'—N1'—H1B'	113.2 (17)
C2—C1—C6	117.15 (9)	C1—C1'—C2'	123.75 (9)
C2—C1—C1'	124.22 (9)	C1—C1'—C6'	118.55 (9)
C6—C1—C1'	118.53 (9)	C2'—C1'—C6'	117.64 (10)
Cl1—C2—C1	120.81 (8)	Cl1'—C2'—C1'	120.31 (8)
Cl1—C2—C3	117.20 (8)	Cl1'—C2'—C3'	118.03 (8)
C1—C2—C3	121.94 (10)	C1'—C2'—C3'	121.60 (10)
C2—C3—C4	120.56 (10)	C2'—C3'—C4'	120.22 (10)
C2—C3—H3	120.5 (9)	C2'—C3'—H3'	119.8 (9)
C4—C3—H3	118.9 (9)	C4'—C3'—H3'	120.0 (9)
N1—C4—C3	121.75 (10)	N1'—C4'—C3'	122.04 (10)
N1—C4—C5	119.82 (10)	N1'—C4'—C5'	118.89 (10)
C3—C4—C5	118.33 (10)	C3'—C4'—C5'	118.84 (10)
O1—C5—C4	115.15 (9)	O1'—C5'—C4'	114.80 (9)
O1—C5—C6	124.47 (9)	O1'—C5'—C6'	124.94 (10)
C4—C5—C6	120.39 (10)	C4'—C5'—C6'	120.26 (10)
C1—C6—C5	121.61 (10)	C1'—C6'—C5'	121.40 (10)
C1—C6—H6	115.7 (9)	C1'—C6'—H6'	115.0 (9)
C5—C6—H6	122.7 (9)	C5'—C6'—H6'	123.6 (9)
O1—C7—C8	107.69 (9)	O1'—C7'—C8'	108.37 (9)
O1—C7—H7A	109.0 (8)	O1'—C7'—H7A'	108.4 (8)
O1—C7—H7B	108.6 (9)	O1'—C7'—H7B'	108.9 (8)
C8—C7—H7A	110.7 (8)	C8'—C7'—H7A'	110.4 (8)
C8—C7—H7B	109.5 (9)	C8'—C7'—H7B'	112.4 (9)
H7A—C7—H7B	111.2 (12)	H7A'—C7'—H7B'	108.2 (12)
C7—C8—C9	110.55 (10)	C7'—C8'—C9'	109.83 (10)
C7—C8—H8A	109.5 (9)	C7'—C8'—H8A'	108.8 (9)
C7—C8—H8B	107.5 (9)	C7'—C8'—H8B'	108.9 (9)
C9—C8—H8A	109.0 (9)	C9'—C8'—H8A'	111.7 (9)
C9—C8—H8B	113.3 (9)	C9'—C8'—H8B'	109.4 (8)
H8A—C8—H8B	106.9 (13)	H8A'—C8'—H8B'	108.1 (13)
C8—C9—H9A	109.3 (10)	C8'—C9'—H9A'	110.9 (9)
C8—C9—H9B	110.7 (10)	C8'—C9'—H9B'	109.7 (9)
C8—C9—H9C	110.3 (9)	C8'—C9'—H9C'	114.4 (11)
H9A—C9—H9B	109.2 (14)	H9A'—C9'—H9B'	110.7 (13)
H9A—C9—H9C	108.8 (13)	H9A'—C9'—H9C'	105.3 (14)
H9B—C9—H9C	108.5 (14)	H9B'—C9'—H9C'	105.7 (14)
C2—C1—C1'—C2'	67.20 (16)	C2—C1—C1'—C6'	−115.7 (2)
C6—C1—C1'—C2'	−116.7 (2)	C6—C1—C1'—C6'	60.45 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	1.01	2.39	2.6937 (13)	96
N1′—H1A′···O1′	1.01	2.30	2.6715 (14)	100
N1—H1A···N1′^i	1.01	2.59	3.5563 (15)	161
N1—H1B···N1′^ii	1.01	2.55	3.5492 (15)	169

Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) x−1/2, −y+1/2, z−1/2.

(II) 2,2'-dimethyl-5,5'-dipropoxybenzidine

Crystal data

C20H28N2O2	F(000) = 712.40
Mr = 328.45	Dx = 1.220 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.1703 (3) Å	Cell parameters from 25 reflections
b = 23.0083 (9) Å	θ = 16.0–18.0°
c = 10.8483 (6) Å	µ = 0.08 mm^−1
β = 91.704 (3)°	T = 148 K
V = 1788.92 (14) Å^3	Cut sword, light amber
Z = 4	0.60 × 0.38 × 0.10 mm

Data collection

Enraf-Nonius CAD-4 MACH diffractometer	Rint = 0.000
Radiation source: X-ray tube	θmax = 25.0°, θmin = 1.2°
Graphite monochromator	h = −8→8
ω scan b/P/b	k = 0→27
3129 measured reflections	l = 0→12
3129 independent reflections	3 standard reflections every 80 min
2348 reflections with Inet > σ(Inet)	intensity decay: 1.6%

Refinement

Refinement on F	305 parameters
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.051	Weighting scheme based on measured s.u.'s 1/(σ^2(F) + 0.0007F^2)
wR(F^2) = 0.056	(Δ/σ)max < 0.001
S = 1.43	Δρmax = 0.22 e Å^−3
2341 reflections	Δρmin = −0.25 e Å^−3

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

	x	y	z	Uiso*/Ueq
C1	0.6323 (3)	0.23271 (10)	0.60610 (18)	0.0151 (11)
C2	0.4871 (3)	0.21472 (10)	0.52404 (19)	0.0166 (12)
C3	0.4916 (3)	0.15849 (10)	0.4772 (2)	0.0176 (11)
C4	0.6341 (3)	0.11928 (10)	0.5053 (2)	0.0166 (11)
N1	0.6407 (3)	0.06388 (9)	0.4530 (2)	0.0234 (11)
C5	0.7810 (3)	0.13828 (10)	0.58551 (19)	0.0152 (11)
C6	0.7781 (3)	0.19365 (10)	0.63407 (19)	0.0158 (11)
C7	0.3306 (4)	0.25486 (12)	0.4836 (2)	0.0223 (12)
O1	0.9188 (2)	0.09745 (7)	0.60869 (14)	0.0193 (8)
C8	1.0859 (3)	0.11799 (10)	0.6725 (2)	0.0176 (12)
C9	1.2243 (3)	0.06867 (11)	0.6784 (2)	0.0212 (12)
C10	1.3861 (4)	0.08261 (13)	0.7680 (3)	0.0274 (13)
C1'	0.6415 (3)	0.29279 (10)	0.65889 (19)	0.0150 (11)
C2'	0.5128 (3)	0.31352 (10)	0.74415 (19)	0.0157 (11)
C3'	0.5334 (3)	0.37028 (10)	0.7882 (2)	0.0175 (11)
C4'	0.6772 (3)	0.40653 (10)	0.75406 (19)	0.0157 (10)
N1'	0.7057 (3)	0.46191 (9)	0.80662 (19)	0.0211 (10)
C5'	0.8084 (3)	0.38496 (10)	0.67101 (19)	0.0154 (10)
C6'	0.7890 (3)	0.32910 (10)	0.6250 (2)	0.0163 (11)
C7'	0.3598 (4)	0.27529 (12)	0.7925 (2)	0.0214 (13)
O1'	0.9477 (2)	0.42341 (7)	0.64203 (14)	0.0202 (8)
C8'	1.1029 (3)	0.39999 (11)	0.5768 (2)	0.0182 (11)
C9'	1.2356 (3)	0.44870 (11)	0.5475 (2)	0.0217 (12)
C10'	1.3864 (4)	0.42699 (12)	0.4629 (2)	0.0249 (13)
H1A	0.705 (5)	0.0351 (16)	0.500 (4)	0.071 (11)*
H1B	0.532 (4)	0.0503 (13)	0.419 (3)	0.041 (8)*
H3	0.391 (4)	0.1441 (11)	0.422 (2)	0.0276*
H6	0.883 (4)	0.2070 (11)	0.687 (2)	0.0258*
H7A	0.369 (4)	0.2970 (13)	0.479 (2)	0.0321*
H7B	0.278 (3)	0.2450 (11)	0.400 (3)	0.0321*
H7C	0.221 (4)	0.2544 (11)	0.539 (3)	0.0321*
H8A	1.139 (4)	0.1543 (11)	0.630 (2)	0.0276*
H8B	1.047 (3)	0.1302 (11)	0.758 (2)	0.0276*
H9A	1.160 (4)	0.0325 (11)	0.704 (2)	0.0312*
H9B	1.269 (4)	0.0597 (11)	0.594 (3)	0.0312*
H10A	1.455 (4)	0.1200 (13)	0.745 (3)	0.0373*
H10B	1.477 (4)	0.0465 (12)	0.771 (2)	0.0373*
H10C	1.338 (4)	0.0901 (12)	0.854 (3)	0.0373*
H1A'	0.766 (4)	0.4885 (12)	0.760 (3)	0.031 (8)*
H1B'	0.603 (4)	0.4791 (12)	0.834 (3)	0.032 (8)*
H3'	0.448 (4)	0.3864 (11)	0.844 (2)	0.0274*
H6'	0.877 (3)	0.3142 (11)	0.565 (2)	0.0262*
H7A'	0.381 (4)	0.2341 (12)	0.780 (2)	0.0314*
H7B'	0.229 (4)	0.2859 (11)	0.757 (2)	0.0314*
H7C'	0.352 (4)	0.2781 (11)	0.879 (3)	0.0314*
H8A'	1.166 (4)	0.3704 (12)	0.627 (2)	0.0282*
H8B'	1.054 (3)	0.3798 (11)	0.497 (2)	0.0282*
H9A'	1.166 (4)	0.4811 (12)	0.510 (2)	0.0316*
H9B'	1.293 (4)	0.4633 (11)	0.628 (3)	0.0316*
H10A'	1.467 (4)	0.3940 (12)	0.501 (3)	0.0350*
H10B'	1.473 (4)	0.4608 (12)	0.441 (2)	0.0350*
H10C'	1.325 (4)	0.4091 (12)	0.383 (3)	0.0350*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0147 (12)	0.0217 (13)	0.0088 (10)	−0.0010 (10)	0.0005 (8)	0.0004 (9)
C2	0.0151 (12)	0.0234 (13)	0.0113 (11)	−0.0023 (10)	0.0007 (9)	0.0013 (9)
C3	0.0158 (12)	0.0253 (13)	0.0117 (11)	−0.0058 (10)	−0.0014 (9)	−0.0004 (9)
C4	0.0188 (12)	0.0188 (12)	0.0122 (11)	−0.0018 (10)	0.0008 (9)	−0.0012 (9)
N1	0.0227 (12)	0.0225 (12)	0.0247 (11)	−0.0026 (10)	−0.0047 (9)	−0.0041 (9)
C5	0.0138 (11)	0.0193 (12)	0.0126 (11)	0.0023 (10)	0.0007 (9)	0.0015 (9)
C6	0.0117 (11)	0.0237 (13)	0.0121 (11)	−0.0033 (10)	−0.0003 (9)	−0.0005 (9)
C7	0.0200 (14)	0.0281 (15)	0.0183 (13)	0.0016 (11)	−0.0080 (10)	−0.0011 (10)
O1	0.0160 (8)	0.0197 (9)	0.0218 (8)	0.0011 (7)	−0.0042 (7)	−0.0026 (7)
C8	0.0135 (12)	0.0231 (13)	0.0162 (12)	−0.0011 (10)	−0.0018 (9)	−0.0009 (10)
C9	0.0181 (13)	0.0238 (14)	0.0217 (13)	−0.0005 (11)	−0.0012 (10)	0.0017 (10)
C10	0.0186 (14)	0.0341 (16)	0.0292 (14)	0.0003 (12)	−0.0068 (11)	0.0037 (12)
C1'	0.0138 (11)	0.0201 (12)	0.0106 (10)	0.0017 (9)	−0.0062 (9)	0.0018 (9)
C2'	0.0139 (12)	0.0236 (13)	0.0094 (10)	0.0034 (10)	−0.0036 (9)	0.0012 (9)
C3'	0.0152 (12)	0.0256 (13)	0.0114 (11)	0.0062 (10)	−0.0025 (9)	−0.0018 (9)
C4'	0.0157 (12)	0.0194 (12)	0.0117 (10)	0.0048 (10)	−0.0064 (9)	0.0006 (9)
N1'	0.0212 (12)	0.0211 (11)	0.0209 (11)	0.0031 (10)	−0.0014 (9)	−0.0035 (9)
C5'	0.0118 (12)	0.0219 (12)	0.0121 (11)	0.0003 (9)	−0.0052 (9)	0.0035 (9)
C6'	0.0150 (12)	0.0234 (13)	0.0103 (11)	0.0025 (10)	−0.0031 (9)	0.0001 (9)
C7'	0.0206 (13)	0.0278 (15)	0.0158 (12)	−0.0004 (11)	0.0017 (10)	−0.0007 (10)
O1'	0.0157 (9)	0.0212 (9)	0.0238 (9)	−0.0012 (7)	0.0011 (7)	−0.0032 (7)
C8'	0.0139 (12)	0.0229 (13)	0.0177 (12)	0.0010 (10)	−0.0015 (10)	−0.0028 (10)
C9'	0.0206 (13)	0.0207 (13)	0.0237 (13)	0.0002 (11)	−0.0004 (10)	−0.0010 (10)
C10'	0.0207 (14)	0.0248 (14)	0.0294 (14)	−0.0021 (11)	0.0040 (11)	−0.0017 (11)

Geometric parameters (Å, º)

C1—C2	1.412 (3)	C1'—C2'	1.409 (3)
C1—C6	1.405 (3)	C1'—C6'	1.405 (3)
C1—C1'	1.497 (3)	C2'—C3'	1.397 (3)
C2—C3	1.391 (3)	C2'—C7'	1.512 (3)
C2—C7	1.508 (3)	C3'—C4'	1.385 (3)
C3—C4	1.390 (3)	C3'—H3'	0.95 (3)
C3—H3	0.98 (3)	C4'—N1'	1.408 (3)
C4—N1	1.397 (3)	C4'—C5'	1.412 (3)
C4—C5	1.416 (3)	N1'—H1A'	0.91 (3)
N1—H1A	0.95 (4)	N1'—H1B'	0.90 (3)
N1—H1B	0.90 (3)	C5'—C6'	1.384 (3)
C5—C6	1.379 (3)	C5'—O1'	1.378 (3)
C5—O1	1.381 (3)	C6'—H6'	0.98 (3)
C6—H6	0.98 (3)	C7'—H7A'	0.97 (3)
C7—H7A	1.01 (3)	C7'—H7B'	1.03 (3)
C7—H7B	1.00 (3)	C7'—H7C'	0.94 (3)
C7—H7C	1.00 (3)	O1'—C8'	1.441 (3)
O1—C8	1.445 (3)	C8'—C9'	1.510 (3)
C8—C9	1.508 (3)	C8'—H8A'	0.97 (3)
C8—H8A	1.03 (3)	C8'—H8B'	1.04 (3)
C8—H8B	1.01 (3)	C9'—C10'	1.523 (3)
C9—C10	1.526 (3)	C9'—H9A'	0.98 (3)
C9—H9A	0.99 (3)	C9'—H9B'	1.01 (3)
C9—H9B	1.00 (3)	C10'—H10A'	1.03 (3)
C10—H10A	1.03 (3)	C10'—H10B'	1.03 (3)
C10—H10B	1.05 (3)	C10'—H10C'	1.05 (3)
C10—H10C	1.02 (3)
C2—C1—C6	118.6 (2)	C1—C1'—C2'	122.8 (2)
C2—C1—C1'	122.4 (2)	C1—C1'—C6'	118.30 (19)
C6—C1—C1'	118.94 (19)	C2'—C1'—C6'	118.9 (2)
C1—C2—C3	118.6 (2)	C1'—C2'—C3'	118.4 (2)
C1—C2—C7	122.1 (2)	C1'—C2'—C7'	121.8 (2)
C3—C2—C7	119.3 (2)	C3'—C2'—C7'	119.7 (2)
C2—C3—C4	123.3 (2)	C2'—C3'—C4'	122.9 (2)
C2—C3—H3	120.8 (15)	C2'—C3'—H3'	121.2 (15)
C4—C3—H3	116.0 (15)	C4'—C3'—H3'	115.9 (15)
C3—C4—N1	122.5 (2)	C3'—C4'—N1'	122.5 (2)
C3—C4—C5	117.6 (2)	C3'—C4'—C5'	118.3 (2)
N1—C4—C5	119.9 (2)	N1'—C4'—C5'	119.0 (2)
C4—N1—H1A	115 (2)	C4'—N1'—H1A'	116.6 (17)
C4—N1—H1B	116.2 (18)	C4'—N1'—H1B'	114.9 (17)
H1A—N1—H1B	111 (3)	H1A'—N1'—H1B'	107 (2)
C4—C5—C6	120.0 (2)	C4'—C5'—C6'	119.7 (2)
C4—C5—O1	114.66 (19)	C4'—C5'—O1'	114.91 (19)
C6—C5—O1	125.31 (19)	C6'—C5'—O1'	125.4 (2)
C1—C6—C5	121.9 (2)	C1'—C6'—C5'	121.7 (2)
C1—C6—H6	118.7 (14)	C1'—C6'—H6'	118.0 (15)
C5—C6—H6	119.4 (14)	C5'—C6'—H6'	120.2 (15)
C2—C7—H7A	113.7 (15)	C2'—C7'—H7A'	113.5 (15)
C2—C7—H7B	112.4 (14)	C2'—C7'—H7B'	113.2 (14)
C2—C7—H7C	114.2 (15)	C2'—C7'—H7C'	111.8 (16)
H7A—C7—H7B	105 (2)	H7A'—C7'—H7B'	108 (2)
H7A—C7—H7C	105 (2)	H7A'—C7'—H7C'	102 (2)
H7B—C7—H7C	105 (2)	H7B'—C7'—H7C'	105 (2)
C5—O1—C8	116.29 (17)	C5'—O1'—C8'	116.59 (17)
O1—C8—C9	108.00 (18)	O1'—C8'—C9'	109.03 (19)
O1—C8—H8A	111.1 (14)	O1'—C8'—H8A'	110.0 (15)
O1—C8—H8B	106.4 (14)	O1'—C8'—H8B'	109.3 (13)
C9—C8—H8A	112.2 (14)	C9'—C8'—H8A'	110.6 (15)
C9—C8—H8B	111.6 (14)	C9'—C8'—H8B'	111.0 (14)
H8A—C8—H8B	107 (2)	H8A'—C8'—H8B'	106 (2)
C8—C9—C10	110.8 (2)	C8'—C9'—C10'	110.3 (2)
C8—C9—H9A	109.4 (15)	C8'—C9'—H9A'	109.6 (15)
C8—C9—H9B	110.3 (15)	C8'—C9'—H9B'	108.0 (15)
C10—C9—H9A	110.2 (15)	C10'—C9'—H9A'	111.4 (16)
C10—C9—H9B	111.5 (15)	C10'—C9'—H9B'	110.4 (15)
H9A—C9—H9B	104 (2)	H9A'—C9'—H9B'	107 (2)
C9—C10—H10A	112.7 (15)	C9'—C10'—H10A'	113.6 (15)
C9—C10—H10B	108.2 (15)	C9'—C10'—H10B'	109.8 (15)
C9—C10—H10C	110.4 (15)	C9'—C10'—H10C'	109.8 (14)
H10A—C10—H10B	111 (2)	H10A'—C10'—H10B'	108 (2)
H10A—C10—H10C	104 (2)	H10A'—C10'—H10C'	105 (2)
H10B—C10—H10C	109 (2)	H10B'—C10'—H10C'	110 (2)
C2—C1—C1'—C2'	68.3 (3)	C2—C1—C1'—C6'	−113.9 (4)
C6—C1—C1'—C2'	−115.0 (4)	C6—C1—C1'—C6'	62.8 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	1.01	2.38	2.689 (3)	97
N1′—H1A′···O1′	1.01	2.37	2.677 (3)	96
N1—H1A···N1′^i	1.01	2.69	3.654 (3)	160
N1—H1B···N1′^ii	1.01	2.52	3.508 (3)	165

Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) x−1/2, −y+1/2, z−1/2.