Crystal structure of 2-amino-5,6,7,8-tetra­hydro-7,7-dimethyl-4-(naphthalen-2-yl)-5-oxo-4H-chromene-3-carbo­nitrile

Hebishy, A.M.S.; Elgemeie, G.H.; Ali, R.A.E.; Jones, P.G.

doi:10.1107/S2056989022005199

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ISSN: 2056-9890

Volume 78| Part 6| June 2022| Pages 638-641

https://doi.org/10.1107/S2056989022005199

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Crystal structure of 2-amino-5,6,7,8-tetrahydro-7,7-dimethyl-4-(naphthalen-2-yl)-5-oxo-4H-chromene-3-carbonitrile

Ali M. S. Hebishy,^a Galal H. Elgemeie,^a Rasha A. E. Ali ^a and Peter G. Jones ^b ^*

^aChemistry Department, Faculty of Science, Helwan University, Cairo, Egypt, and ^bInstitut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany
^*Correspondence e-mail: p.jones@tu-bs.de

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 29 April 2022; accepted 13 May 2022; online 20 May 2022)

In the title compound, C₂₂H₂₀N₂O₂, both six-membered rings of the fused heterocyclic system display envelope conformations; the two carbon atoms bearing the methyl groups and the naphthyl substituent both lie outside the planes of the other atoms of each ring. In the crystal, the amino group forms hydrogen bonds of the types N—H⋯O=C and N—H⋯N≡C, leading to the formation of a double layer structure propagating parallel to the bc plane. Weak C—H⋯O and C—H⋯π interactions may reinforce the layers.

Keywords: chromene; naphthyl; crystal structure.

CCDC reference: 2172530

1. Chemical context

Six-membered heterocycles involving 4H-pyran units represent an important class of biologically active synthetic and natural products, many of which attract the interest of the drug industry (Lega et al., 2016 ). Pyrans possess antimicrobial (Dazmiri et al., 2020 ), antituberculosis (Kalaria et al., 2014 ) and antitumor (Wang et al., 2014 ) activities, whereby 4H-pyrans are moieties in a series of natural products (Singh et al., 1996 ). A number of 4H-pyrans are used, for example, as photoactive ingredients (Armesto et al., 1989 ) or agrochemicals (Kumar et al., 2009 ). Synthetically, they are intermediates for the synthesis of heterocyclic compounds such as pyranopyrimidines and pyranopyrazoles (Elgemeie et al., 1987 , 1988 ) and consequently the synthesis of 4H-pyrans themselves is of interest to organic chemists.

Some time ago, we reported the synthesis of pyridine-2(1H)-thiones and their condensed derivatives from the reactions of arylmethylenecyanothioacetamides with suitable active methylene compounds (Elgemeie et al., 2002 ).We also described the reaction of the dimedone 1 with naphthylmethylenecyanothioacetamide to produce a condensed pyridine-2(1H)-thione (Attia et al., 1997 ). The course of this reaction prompted us to investigate how 1 would react with naphthylmethylenecyanoacetamide [2-cyano-3-(naphthalen-2-yl)acrylamide, 2] in boiling ethanol containing triethylamine. The product was shown to be neither of the expected condensed pyridin-2(1H)-ones 3 or 4 but rather the condensed pyran nitrile 5 (Scheme 1). The latter structure was inferred on the basis of elemental analysis and spectroscopic data: thus, the mass spectrum of 5 was compatible with the molecular formula C₂₂H₂₀N₂O₂ (M⁺, 344), and the ¹H NMR spectrum had signals at 4.37 (pyran-4H), 7.06 (br, NH₂) and 7.29–7.90 (m, ArH).

We assume that the formation of 5 proceeds via addition of the active methylene group of 1 to the double bond of 2 to give the intermediates 6, 7 and then 8, the latter finally losing one molecule of water to give the final product 5 (Scheme 2). In order to establish the structure of this compound unambiguously, its crystal structure was determined and is reported here.

2. Structural commentary

The molecular structure of 5 is shown in Fig. 1 and it confirms the postulated structure noted above. Both six-membered rings display envelope conformations in which five atoms are reasonably coplanar (for torsion angles see Table 1): C4 deviates by 0.317 (1) Å from the mean plane (I) of atoms O1/C2/C3/C4A/C8A (r.m.s. deviation = 0.031 Å), and C7 lies 0.653 (2) Å outside the mean plane (II) of C4A/C5–C8 (r.m.s. deviation = 0.030 Å). The interplanar angle I/II is 9.97 (4)°. The naphthyl ring system (r.m.s. deviation = 0.012 Å) is effectively perpendicular to plane I [interplanar angle = 86.56 (3)°]. The amino group is almost planar (r.m.s. deviation of C2/N1/H01/H02 = 0.01 Å) and deviates slightly from plane I [interplanar angle = 10.0 (6)°].

Table 1
Selected torsion angles (°)

C8A—O1—C2—C3	−8.36 (13)	C5—C6—C7—C8	54.40 (11)
O1—C2—C3—C4	−9.65 (14)	C6—C7—C8—C8A	−47.78 (11)
C2—C3—C4—C4A	22.65 (13)	C4—C4A—C8A—O1	5.99 (15)
C3—C4—C4A—C8A	−20.86 (12)	C5—C4A—C8A—C8	5.73 (15)
C8A—C4A—C5—C6	0.61 (14)	C2—O1—C8A—C4A	10.40 (13)
C4A—C5—C6—C7	−31.83 (13)	C7—C8—C8A—C4A	19.52 (14)

Figure 1
The molecular structure of 5 in the crystal. Ellipsoids represent 50% probability levels.

3. Supramolecular features

In the crystal, the amino group acts as donor for two classical hydrogen bonds (Table 2). This leads to a double layer structure (Fig. 2) propagating parallel to the bc plane. The H⋯O separation of the weak hydrogen bond C6—H6B⋯N2 (x, −1 + y, z) is rather long at 2.69 Å but acceptably linear (160°) and presumably reinforces the layer structure, but is not shown in Fig. 2. The short contact C10—H10B⋯Cg (C12–16/C21), with H⋯Cg 2.79 Å and a C—H⋯Cg angle of 139°, may represent a C—H⋯π interaction between the double layers. There are no short π–π stacking contacts.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H01⋯N2ⁱ	0.90 (1)	2.11 (1)	2.9948 (12)	170 (1)
N1—H02⋯O2ⁱⁱ	0.90 (1)	1.94 (1)	2.8404 (11)	176 (1)
C6—H6B⋯N2ⁱⁱⁱ	0.99	2.69	3.6366 (14)	160
Symmetry codes: (i) ; (ii) $[x, -y+1, z-{\script{1\over 2}}]$ ; (iii) .

Figure 2
Crystal packing of 5 viewed parallel to the a axis in the region x ≃ 0.5. Dashed lines indicate classical hydrogen bonds. Naphthyl rings are reduced to the ipso carbon atoms for clarity. Hydrogen atoms not involved in classical hydrogen bonding are omitted. The figure is depth-coded; molecules of the lower layer are drawn with thinner bonds. Atom labels indicate the asymmetric unit (which lies in the lower layer).

4. Database survey

A search of the Cambridge Database (Version 2021.3.0; Groom et al., 2016 ) showed that the motif of a 4-substituted 2-amino-5,6,7,8-tetrahydro-7,7-dimethyl-5-oxo-4H-chromene-3-carbonitrile has been the subject of many structure determinations. A total of 54 hits with variously substituted phenyl groups was found, which reduces to 32 when duplicate structure determinations, various solvates and polymorphs are not considered. For all but one of these structures, the 4-position also bears a hydrogen atom, the exception being the 4-methyl, 4-nitrophenyl derivative (Cai et al., 2012 ; refcode TESNEM). Additionally, the 4-(1-naphthyl) derivative was found (Nesterov et al., 2004 ; refcode ETOKIH), which is an isomer of the title compound 5. The packing of ETOKIH is quite different from that of 5; the hydrogen atom corresponding to H01 in 5 forms N—H⋯N hydrogen bonds, leading to inversion dimers, whereas the other NH hydrogen atom is not involved in hydrogen bonding. A least-squares overlay of 5 and ETOKIH (excluding methyl groups and all naphthyl carbon atoms except the ipso C atom) gave an r.m.s. deviation of 0.15 Å; Fig. 3 shows the slight differences in ring conformation.

Figure 3
A least-squares fit of 5 (violet, full bonds) to ETOKIH (Nesterov et al., 2004

; green, dashed bonds). Hydrogen atoms were not considered.

5. Synthesis and crystallization

A mixture of dimedone 1 (0.010 mol), 2-cyano-3-(naphthalen-2-yl)acrylamide 2 (0.010 mol) and triethylamine (0.010 mol) in ethanol (10 ml) was refluxed for 2 h. The solid precipitate that formed was filtered off and recrystallized from ethanol solution to give pale yellow crystals of 5 in 90% yield, m.p. 474–475 K; IR (KBr, cm⁻¹): υ 3345, 3258 (NH₂), 2188 (CN), 1683 (C=O). ¹H NMR (400 MHz DMSO-d₆) δ: 1.11 (s, 3H, CH₃), 1.53 (s, 3H, CH₃), 2.07 (d, 2H, CH₂), 2.14 (d, 2H, CH₂), 4.37 (s, 1H, CH-pyran), 7.06 (s, br, 2H, NH₂), 7.29–7.90 (m, 7H, C₁₀H₇). ¹³C NMR (100 MHz, DMSO-d₆) δ: 27.2, 28.8, 32.2, 36.3, 50.4, 58.6 (aliphatic C), 120.2 (CN), 113.0, 142.2, 158.9, 163.0 (ethylene C), 120.2-133.3 (aromatic C), 196.2 (C=O). MS (EI): m/z 344 [M⁺]. Analysis calculated for C₂₂H₂₀N₂O₂: C 76.72; H 5.85; N 8.13%. Found: C 76.6; H 5.7; N 8.1%.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The hydrogen atoms of the NH₂ group were refined freely, but with N—H distances restrained to be approximately equal using a SADI instruction in SHELXL. The methyl groups were included as idealised rigid groups allowed to rotate but not tip (C—H = 0.98 Å; H—C—H = 109.5°). The other hydrogen atoms were included using a riding model starting from calculated positions (C—H = 0.95, 0.98 and 1.00 Å for aromatic, methylene and methine H atoms, respectively). The U_iso(H) values were fixed at 1.5 × U_eq of the parent carbon atoms for the methyl groups and 1.2 × U_eq for other hydrogen atoms.

Table 3
Experimental details

Crystal data
Chemical formula	C₂₂H₂₀N₂O₂
M_r	344.40
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	100
a, b, c (Å)	25.3144 (3), 9.25765 (11), 15.6778 (2)
β (°)	97.8724 (10)
V (Å³)	3639.51 (8)
Z	8
Radiation type	Cu Kα
μ (mm⁻¹)	0.65
Crystal size (mm)	0.08 × 0.05 × 0.02

Data collection
Diffractometer	XtaLAB Synergy, HyPix
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku OD, 2021 $[Rigaku OD (2021). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ )
T_min, T_max	0.826, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	61093, 3856, 3694
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.634

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.086, 1.07
No. of reflections	3856
No. of parameters	245
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.20
Computer programs: CrysAlis PRO (Rigaku OD, 2021 $[Rigaku OD (2021). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ ), SHELXT (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ) and XP (Siemens, 1994 ).

Supporting information

CCDC reference: 2172530

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2056989022005199/hb8021sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022005199/hb8021Isup2.hkl

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2021); cell refinement: CrysAlis PRO (Rigaku OD, 2021); data reduction: CrysAlis PRO (Rigaku OD, 2021); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL2018/3 (Sheldrick, 2015b).

2-Amino-5,6,7,8-tetrahydro-7,7-dimethyl-4-(naphthalen-2-yl)-5-oxo-4H-chromene-3-carbonitrile top

Crystal data top

C₂₂H₂₀N₂O₂	F(000) = 1456
M_r = 344.40	D_x = 1.257 Mg m⁻³
Monoclinic, C2/c	Cu Kα radiation, λ = 1.54184 Å
a = 25.3144 (3) Å	Cell parameters from 35871 reflections
b = 9.25765 (11) Å	θ = 3.5–77.4°
c = 15.6778 (2) Å	µ = 0.65 mm⁻¹
β = 97.8724 (10)°	T = 100 K
V = 3639.51 (8) Å³	Lath, colourless
Z = 8	0.08 × 0.05 × 0.02 mm

Data collection top

XtaLAB Synergy, HyPix diffractometer	3856 independent reflections
Radiation source: micro-focus sealed X-ray tube	3694 reflections with I > 2σ(I)
Detector resolution: 10.0000 pixels mm^-1	R_int = 0.030
ω scans	θ_max = 77.6°, θ_min = 3.5°
Absorption correction: multi-scan (CrysalisPro; Rigaku OD, 2021)	h = −31→31
T_min = 0.826, T_max = 1.000	k = −11→11
61093 measured reflections	l = −19→19

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.086	w = 1/[σ²(F_o²) + (0.0362P)² + 2.6486P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max < 0.001
3856 reflections	Δρ_max = 0.22 e Å⁻³
245 parameters	Δρ_min = −0.20 e Å⁻³
1 restraint

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

24.6913 (0.0028) x - 2.0266 (0.0045) y - 2.5063 (0.0065) z = 7.9737 (0.0050)

* -0.0099 (0.0006) C4A * -0.0265 (0.0007) C5 * 0.0300 (0.0005) C6 * -0.0353 (0.0005) C8 * 0.0417 (0.0007) C8A -0.6525 (0.0015) C7

Rms deviation of fitted atoms = 0.0306

23.4020 (0.0039) x - 3.5289 (0.0034) y - 1.8463 (0.0073) z = 7.1162 (0.0054)

Angle to previous plane (with approximate esd) = 9.967 ( 0.036 )

* -0.0423 (0.0006) O1 * 0.0228 (0.0006) C2 * -0.0021 (0.0005) C3 * -0.0200 (0.0005) C4A * 0.0415 (0.0006) C8A -0.3166 (0.0014) C4

Rms deviation of fitted atoms = 0.0298

- 6.0033 (0.0056) x - 6.6409 (0.0023) y + 10.6832 (0.0042) z = 0.1010 (0.0050)

Angle to previous plane (with approximate esd) = 86.556 ( 0.027 )

* -0.0188 (0.0008) C12 * -0.0048 (0.0008) C13 * 0.0149 (0.0009) C14 * 0.0098 (0.0010) C15 * -0.0015 (0.0011) C16 * -0.0151 (0.0011) C17 * -0.0093 (0.0011) C18 * 0.0169 (0.0011) C19 * 0.0111 (0.0010) C20 * -0.0032 (0.0010) C21

Rms deviation of fitted atoms = 0.0119

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.42046 (3)	0.54277 (7)	0.46059 (4)	0.01878 (16)
C2	0.44459 (4)	0.67304 (10)	0.48220 (6)	0.01719 (19)
N1	0.45324 (4)	0.74447 (10)	0.41141 (6)	0.02197 (19)
H01	0.4646 (6)	0.8361 (15)	0.4146 (9)	0.038 (4)*
H02	0.4446 (6)	0.7028 (15)	0.3594 (8)	0.036 (4)*
C3	0.45648 (4)	0.71509 (10)	0.56594 (6)	0.0174 (2)
C4	0.43643 (4)	0.63303 (11)	0.63906 (6)	0.0175 (2)
H4	0.465617	0.629568	0.688927	0.021*
C4A	0.42383 (4)	0.48120 (10)	0.60884 (6)	0.0172 (2)
C5	0.42044 (4)	0.36809 (11)	0.67350 (6)	0.0198 (2)
O2	0.42982 (3)	0.39810 (8)	0.75024 (5)	0.02716 (18)
C6	0.40710 (4)	0.21643 (11)	0.64222 (7)	0.0231 (2)
H6A	0.389602	0.164811	0.686041	0.028*
H6B	0.440604	0.164729	0.636056	0.028*
C7	0.37033 (4)	0.21205 (11)	0.55576 (7)	0.0223 (2)
C8	0.39608 (4)	0.30239 (11)	0.49014 (6)	0.0204 (2)
H8A	0.426832	0.248784	0.473153	0.025*
H8B	0.369856	0.316614	0.437883	0.025*
C8A	0.41454 (4)	0.44589 (10)	0.52524 (6)	0.01697 (19)
C9	0.48381 (4)	0.84661 (11)	0.58446 (6)	0.0183 (2)
N2	0.50703 (4)	0.95261 (10)	0.60116 (6)	0.0238 (2)
C10	0.36359 (5)	0.05655 (12)	0.52270 (8)	0.0311 (3)
H10A	0.338967	0.055087	0.468724	0.047*
H10B	0.349210	−0.003296	0.565660	0.047*
H10C	0.398300	0.018361	0.512555	0.047*
C11	0.31556 (4)	0.27340 (14)	0.56747 (8)	0.0312 (3)
H11A	0.320032	0.368819	0.594563	0.047*
H11B	0.298005	0.208440	0.604174	0.047*
H11C	0.293616	0.282185	0.511149	0.047*
C12	0.33761 (4)	0.68876 (11)	0.62556 (6)	0.0203 (2)
H12	0.332117	0.622111	0.579111	0.024*
C13	0.38823 (4)	0.70882 (11)	0.66778 (6)	0.0189 (2)
C14	0.39613 (5)	0.80926 (12)	0.73650 (7)	0.0265 (2)
H14	0.430947	0.823540	0.766542	0.032*
C15	0.35431 (5)	0.88596 (13)	0.76020 (7)	0.0330 (3)
H15	0.360637	0.953461	0.806098	0.040*
C16	0.30184 (5)	0.86665 (13)	0.71766 (7)	0.0308 (3)
C17	0.25720 (6)	0.94476 (16)	0.73986 (9)	0.0462 (4)
H17	0.262423	1.014310	0.784776	0.055*
C18	0.20725 (6)	0.92164 (18)	0.69796 (10)	0.0517 (4)
H18	0.178037	0.975221	0.713572	0.062*
C19	0.19874 (5)	0.81873 (17)	0.63165 (10)	0.0460 (4)
H19	0.163632	0.801759	0.603416	0.055*
C20	0.24071 (5)	0.74252 (14)	0.60733 (8)	0.0336 (3)
H20	0.234466	0.674176	0.561864	0.040*
C21	0.29329 (4)	0.76481 (12)	0.64938 (7)	0.0249 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0252 (4)	0.0155 (3)	0.0155 (3)	−0.0050 (3)	0.0022 (3)	0.0003 (3)
C2	0.0174 (4)	0.0155 (4)	0.0189 (5)	−0.0018 (3)	0.0030 (3)	−0.0002 (4)
N1	0.0322 (5)	0.0182 (4)	0.0159 (4)	−0.0071 (4)	0.0049 (3)	−0.0012 (3)
C3	0.0179 (4)	0.0165 (5)	0.0176 (5)	−0.0017 (4)	0.0024 (3)	0.0004 (4)
C4	0.0204 (5)	0.0176 (5)	0.0141 (4)	−0.0018 (4)	0.0005 (3)	0.0008 (4)
C4A	0.0162 (4)	0.0164 (5)	0.0190 (5)	0.0003 (3)	0.0025 (3)	0.0014 (4)
C5	0.0195 (5)	0.0199 (5)	0.0204 (5)	0.0019 (4)	0.0036 (4)	0.0030 (4)
O2	0.0386 (4)	0.0249 (4)	0.0177 (4)	0.0001 (3)	0.0028 (3)	0.0039 (3)
C6	0.0281 (5)	0.0175 (5)	0.0238 (5)	−0.0008 (4)	0.0038 (4)	0.0050 (4)
C7	0.0246 (5)	0.0179 (5)	0.0247 (5)	−0.0042 (4)	0.0042 (4)	0.0025 (4)
C8	0.0238 (5)	0.0171 (5)	0.0207 (5)	−0.0023 (4)	0.0042 (4)	−0.0006 (4)
C8A	0.0163 (4)	0.0160 (4)	0.0189 (5)	0.0003 (3)	0.0036 (3)	0.0030 (4)
C9	0.0196 (5)	0.0203 (5)	0.0148 (4)	0.0007 (4)	0.0023 (3)	0.0008 (4)
N2	0.0290 (5)	0.0208 (4)	0.0210 (4)	−0.0049 (4)	0.0018 (3)	−0.0004 (3)
C10	0.0423 (7)	0.0197 (5)	0.0308 (6)	−0.0092 (5)	0.0036 (5)	0.0022 (4)
C11	0.0219 (5)	0.0343 (6)	0.0380 (6)	−0.0061 (5)	0.0062 (5)	0.0034 (5)
C12	0.0256 (5)	0.0172 (5)	0.0188 (5)	0.0001 (4)	0.0054 (4)	0.0007 (4)
C13	0.0265 (5)	0.0162 (5)	0.0148 (4)	−0.0013 (4)	0.0057 (4)	0.0018 (4)
C14	0.0361 (6)	0.0251 (5)	0.0183 (5)	−0.0046 (4)	0.0041 (4)	−0.0030 (4)
C15	0.0524 (7)	0.0264 (6)	0.0228 (5)	0.0005 (5)	0.0143 (5)	−0.0063 (4)
C16	0.0433 (7)	0.0259 (6)	0.0274 (6)	0.0071 (5)	0.0193 (5)	0.0043 (5)
C17	0.0621 (9)	0.0411 (8)	0.0421 (7)	0.0186 (7)	0.0304 (7)	0.0038 (6)
C18	0.0496 (8)	0.0577 (9)	0.0551 (9)	0.0287 (7)	0.0329 (7)	0.0181 (7)
C19	0.0308 (7)	0.0577 (9)	0.0527 (8)	0.0146 (6)	0.0174 (6)	0.0211 (7)
C20	0.0270 (6)	0.0363 (6)	0.0391 (7)	0.0045 (5)	0.0098 (5)	0.0102 (5)
C21	0.0291 (5)	0.0219 (5)	0.0261 (5)	0.0029 (4)	0.0121 (4)	0.0071 (4)

Geometric parameters (Å, º) top

O1—C2	1.3733 (11)	C17—C18	1.359 (2)
O1—C8A	1.3769 (11)	C18—C19	1.405 (2)
C2—N1	1.3355 (13)	C19—C20	1.3724 (18)
C2—C3	1.3628 (13)	C20—C21	1.4172 (17)
C3—C9	1.4109 (13)	N1—H01	0.895 (13)
C3—C4	1.5193 (13)	N1—H02	0.901 (13)
C4—C4A	1.5035 (13)	C4—H4	1.0000
C4—C13	1.5278 (14)	C6—H6A	0.9900
C4A—C8A	1.3400 (14)	C6—H6B	0.9900
C4A—C5	1.4681 (13)	C8—H8A	0.9900
C5—O2	1.2259 (13)	C8—H8B	0.9900
C5—C6	1.5101 (14)	C10—H10A	0.9800
C6—C7	1.5362 (15)	C10—H10B	0.9800
C7—C10	1.5316 (15)	C10—H10C	0.9800
C7—C11	1.5323 (15)	C11—H11A	0.9800
C7—C8	1.5384 (14)	C11—H11B	0.9800
C8—C8A	1.4885 (13)	C11—H11C	0.9800
C9—N2	1.1553 (13)	C12—H12	0.9500
C12—C13	1.3721 (14)	C14—H14	0.9500
C12—C21	1.4173 (14)	C15—H15	0.9500
C13—C14	1.4164 (14)	C17—H17	0.9500
C14—C15	1.3678 (17)	C18—H18	0.9500
C15—C16	1.4135 (18)	C19—H19	0.9500
C16—C21	1.4206 (17)	C20—H20	0.9500
C16—C17	1.4244 (17)

C2—O1—C8A	118.69 (7)	C12—C21—C16	118.93 (10)
N1—C2—C3	128.28 (9)	C2—N1—H01	120.8 (9)
N1—C2—O1	110.35 (8)	C2—N1—H02	119.5 (9)
C3—C2—O1	121.37 (9)	H01—N1—H02	119.5 (13)
C2—C3—C9	118.82 (9)	C4A—C4—H4	108.6
C2—C3—C4	122.11 (9)	C3—C4—H4	108.6
C9—C3—C4	118.77 (8)	C13—C4—H4	108.6
C4A—C4—C3	107.94 (8)	C5—C6—H6A	109.0
C4A—C4—C13	112.25 (8)	C7—C6—H6A	109.0
C3—C4—C13	110.83 (8)	C5—C6—H6B	109.0
C8A—C4A—C5	118.84 (9)	C7—C6—H6B	109.0
C8A—C4A—C4	122.52 (9)	H6A—C6—H6B	107.8
C5—C4A—C4	118.63 (8)	C8A—C8—H8A	109.2
O2—C5—C4A	119.62 (9)	C7—C8—H8A	109.2
O2—C5—C6	122.28 (9)	C8A—C8—H8B	109.2
C4A—C5—C6	118.07 (9)	C7—C8—H8B	109.2
C5—C6—C7	113.12 (8)	H8A—C8—H8B	107.9
C10—C7—C11	109.17 (9)	C7—C10—H10A	109.5
C10—C7—C6	110.45 (9)	C7—C10—H10B	109.5
C11—C7—C6	109.48 (9)	H10A—C10—H10B	109.5
C10—C7—C8	108.80 (9)	C7—C10—H10C	109.5
C11—C7—C8	110.60 (9)	H10A—C10—H10C	109.5
C6—C7—C8	108.34 (8)	H10B—C10—H10C	109.5
C8A—C8—C7	112.23 (8)	C7—C11—H11A	109.5
C4A—C8A—O1	122.61 (9)	C7—C11—H11B	109.5
C4A—C8A—C8	125.70 (9)	H11A—C11—H11B	109.5
O1—C8A—C8	111.69 (8)	C7—C11—H11C	109.5
N2—C9—C3	178.34 (11)	H11A—C11—H11C	109.5
C13—C12—C21	121.76 (10)	H11B—C11—H11C	109.5
C12—C13—C14	118.75 (10)	C13—C12—H12	119.1
C12—C13—C4	121.77 (9)	C21—C12—H12	119.1
C14—C13—C4	119.37 (9)	C15—C14—H14	119.5
C15—C14—C13	120.90 (11)	C13—C14—H14	119.5
C14—C15—C16	121.22 (11)	C14—C15—H15	119.4
C15—C16—C21	118.42 (10)	C16—C15—H15	119.4
C15—C16—C17	123.10 (12)	C18—C17—H17	119.4
C21—C16—C17	118.48 (13)	C16—C17—H17	119.4
C18—C17—C16	121.23 (14)	C17—C18—H18	119.9
C17—C18—C19	120.17 (12)	C19—C18—H18	119.9
C20—C19—C18	120.53 (14)	C20—C19—H19	119.7
C19—C20—C21	120.63 (13)	C18—C19—H19	119.7
C20—C21—C12	122.14 (11)	C19—C20—H20	119.7
C20—C21—C16	118.93 (11)	C21—C20—H20	119.7

C8A—O1—C2—N1	171.82 (8)	C4—C4A—C8A—C8	−172.89 (9)
C8A—O1—C2—C3	−8.36 (13)	C2—O1—C8A—C4A	10.40 (13)
N1—C2—C3—C9	−3.54 (16)	C2—O1—C8A—C8	−170.59 (8)
O1—C2—C3—C9	176.67 (9)	C7—C8—C8A—C4A	19.52 (14)
N1—C2—C3—C4	170.13 (10)	C7—C8—C8A—O1	−159.46 (8)
O1—C2—C3—C4	−9.65 (14)	C21—C12—C13—C14	−0.51 (15)
C2—C3—C4—C4A	22.65 (13)	C21—C12—C13—C4	−176.64 (9)
C9—C3—C4—C4A	−163.67 (8)	C4A—C4—C13—C12	−37.80 (12)
C2—C3—C4—C13	−100.65 (11)	C3—C4—C13—C12	82.98 (11)
C9—C3—C4—C13	73.03 (11)	C4A—C4—C13—C14	146.09 (9)
C3—C4—C4A—C8A	−20.86 (12)	C3—C4—C13—C14	−93.12 (11)
C13—C4—C4A—C8A	101.57 (11)	C12—C13—C14—C15	−0.50 (16)
C3—C4—C4A—C5	160.51 (8)	C4—C13—C14—C15	175.72 (10)
C13—C4—C4A—C5	−77.05 (11)	C13—C14—C15—C16	0.66 (17)
C8A—C4A—C5—O2	178.62 (9)	C14—C15—C16—C21	0.19 (17)
C4—C4A—C5—O2	−2.71 (14)	C14—C15—C16—C17	−179.62 (12)
C8A—C4A—C5—C6	0.61 (14)	C15—C16—C17—C18	−179.19 (13)
C4—C4A—C5—C6	179.28 (8)	C21—C16—C17—C18	0.99 (19)
O2—C5—C6—C7	150.21 (10)	C16—C17—C18—C19	0.3 (2)
C4A—C5—C6—C7	−31.83 (13)	C17—C18—C19—C20	−1.2 (2)
C5—C6—C7—C10	173.48 (9)	C18—C19—C20—C21	0.8 (2)
C5—C6—C7—C11	−66.28 (11)	C19—C20—C21—C12	−179.56 (11)
C5—C6—C7—C8	54.40 (11)	C19—C20—C21—C16	0.47 (17)
C10—C7—C8—C8A	−167.89 (9)	C13—C12—C21—C20	−178.63 (10)
C11—C7—C8—C8A	72.21 (11)	C13—C12—C21—C16	1.34 (15)
C6—C7—C8—C8A	−47.78 (11)	C15—C16—C21—C20	178.82 (10)
C5—C4A—C8A—O1	−175.40 (8)	C17—C16—C21—C20	−1.36 (16)
C4—C4A—C8A—O1	5.99 (15)	C15—C16—C21—C12	−1.16 (16)
C5—C4A—C8A—C8	5.73 (15)	C17—C16—C21—C12	178.66 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H01···N2ⁱ	0.90 (1)	2.11 (1)	2.9948 (12)	170 (1)
N1—H02···O2ⁱⁱ	0.90 (1)	1.94 (1)	2.8404 (11)	176 (1)
C6—H6B···N2ⁱⁱⁱ	0.99	2.69	3.6366 (14)	160

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

Acknowledgements

The authors acknowledge support by the Open Access Publication Funds of the Technical University of Braunschweig.

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