Hobartine: a tetra­cyclic indole alkaloid extracted from Aristotelia chilensis (maqui)

The natural compound hobartine {systematic name: (1R)-3-[(1S,5S)-(4,4,8-trimethylbicyclo[3.3.1]non-7-en-2-yl)methyl]-2,3-dihydro-1H-indole}, C₂₀H₂₆N₂, (I), is an indole alkaloid isolated from Aristotelia chilensis as part of a study of secondary metabolites from Chilean flora. The colourless compound has a tetra­cyclic structure closely related to the strongly coloured polymorphic structures discussed in Paz et al. [Acta Cryst. (2013), C69, 1509–1512] and Watson et al. [Acta Cryst. (1989), C45, 1322–1324]. The main differences reside in the absence of a keto group in (I) compared with the previous structures, as well as an endo double bond in (I) contrasting with the exo double bond found in the previous structures. The supra­molecular structure of (I) in strongly related to the twofold screw axis, around which isolated chains build up, inter­nally linked by an N—H...N hydrogen bond which is the only significant inter­molecular inter­action present in the structure.

S1. Introduction

Aristotelia chilensis ([Molina] Stuntz, Elaecarpaceae) is a native Chilean tree commonly known as maqui. It is used particularly as an anti-inflammatory agent against kidney pains, stomach ulcers, diverse digestive ailments (tumors and ulcers), fever and healing injuries (Bhakuni et al. 1976). The fruit is a black berry well known for its high concentration of phenolic compounds. Maqui berries are a healthy fruit with high ORAC (Oxygen Radical Absorbance Capacity) anti­oxidant properties (Céspedes et al. 2010). Indole alkaloids have been identified from extracts of maqui, such as aristoteline, aristotelone (Bhakuni et al., 1976), aristotelinine and aristone (Bittner et al., 1978). Continuing our study of naturally occurring products from the Chilean flora, we have isolated from Aristotelia chilensis the indole alkaloid hobartine, (I), which we have characterized by NMR spectroscopy. [No data or information given; remove statement?]

Even if the presence of hobartine in Aristotelia chilensis had not been reported, the compound was known to be present in Aristotelia Peduncularis (Hesse, 1979), and a number of syntheses of the alkaloid have been performed since its discovery (for example, Stevens & Kenney, 1983; Darbre et al., 1984; Gribble & Barden, 1985; Galli et al., 2002). All these latter reports gave the absolute configuration shown in Scheme 1, viz. 9R,12S,14S.

In addition, the compound is closely related to 8-oxo-9-de­hydro­makomakine (II) (Scheme 2), of a similar origin (Aristotelia chilensis) and previously reported in Paz et al. 2013, which was obtained in two polymorphic forms with a remarkable colour difference, viz. crystal of (IIa) were deep red and those of (IIb) were pale yellow.

In order to ascertain unambiguously the relative position of the double bonds in the structure, as well as to confirm the relative configurations of the asymmetric centres, we analyze herein the thus far unreported crystal structure of hobartine, (I). We shall also discuss similarities and differences with polymorphs (IIa) and (IIb).

S2. Experimental

S2.1. Extraction, purification and crystallization

A. chilensis (maqui) was collected in Concepción, VIII Region of Chile (S 36° 50' 01.51'' W 73° 01' 53.75'') in December 2012. Leaves (20 kg) were dried at 313 K, powdered and macerated for 7 d in water acidified with HCl to pH 3. The water layer (50 l) was then separated by filtration, made basic with NaOH to pH 10 and extracted with ethyl acetate (3 × 20 l). The organic layer was concentrated in vacuo to obtain a crude alkaloid fraction. The alkaloid extract was chromatographed on aluminum oxide and eluted with a hexane, hexane–ethyl acetate (1:1 v/v), ethyl acetate, ethyl acetate–methanol (8:2 v/v) gradient. The preparative chromatography was monitored by thin-layer chromatography (TLC; silica gel) and revealed using UV light and, later, Dragendorff's reagent; those fractions showing similar TLC patterns were pooled and subsequently purified by chromatography with the same procedure to give nine fractions. Fraction 8 (2.1 g) was applied to a Sephadex LH-20 column (EtOAc) and further separated by silica-gel CC (200–300 mesh, EtOAc 100%) afforded hobartine (yield 60 mg). Compound (I) was obtained as a white solid from ethyl acetate and was recrystallized from methanol producing colourless crystals suitable for X-ray diffraction analysis.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were identified in an inter­mediate difference map and treated differently in the refinement. H atoms on C atoms were idealized and allowed to ride both in coordinates as in displacement parameters, the latter taken as U_iso(H)= xU_eq(C), with C—H = 0.93 Å and x = 1.2 for aromatic, C—H = 0.97 Å and x = 1.2 for methyl­ene, and C—H = 0.96 Å and x = 1.5 for methyl groups. H atoms attached to N atoms were refined freely. The use of Mo Kα radiation for data collection precluded a trustable determination of the absolute structure from diffraction data alone and the reported configuration was chosen in accordance to the one unanimously agreed in synthetic works in the literature, viz. C9(R), C12(S) and C14(S).

S3. Results and discussion

Fig. 1 shows an ellipsoid plot of the alkaloid. The molecule is made up of a planar indole and a bulky aza­bicycle joined by a central –CH₂– bridge. It is precisely in this bridge where the main differences with the already reported polymorphs of 4,4-di­methyl-8-methyl­ene-3-aza­bicyclo­[3.3.1]non-2-en-2-yl 3-indolyl ketone, denoted (IIa) (Paz et al., 2013) and (IIb) (Watson et al., 1989), are apparent, the site in (IIa)/(IIb) being sp² hybridized and occupied by a ketone group, instead of the sp³ methyl­ene group seen in (I). The effect extends to the neighbouring C9 atom, also with sp² hybridization in (IIa)/(IIb), but a chiral sp³ hybridization in (I). These gross differences are clearly reflected in the distances, angles and torsion angles in the neighbourhood of atom C8, as given in Table 2 where a brief comparison on corresponding data in (I), (IIa) and (IIb) is made.

In this regard, it is worth noting that the most relevant difference between the (lively coloured) polymorphic forms (IIa) and (IIb) was found to be the torsion angle between the indolyl ketone system and the planar portion of the heterocyclic six-membered ring [C3—C8—C9—N10 = -47.8 (6)° in (IIa) versus -20.2 (3)° in (IIb)]. The responsibility for the colour variation was precisely ascribed to this difference in the degree of electronic conjugation it would give rise to. The fact that (I) presents no conjugation whatsoever in this bridging section [C3—C8—C9—N10 = -74.3 (3)°], while its crystals are strictly colourless seems to support this idea put forward in Paz et al. (2013).

Regarding the geometries of the two well-defined groups, the rigid indole and the more flexible 3-aza­bicycle. The former one does not show, as expected, any relevant difference departing from standard uncertainties. Sensible differences are found, however, in the latter and they mainly involve the single (s) or double (d) character which in (I), (IIa) and (IIb) present the bonds C9—N10 (s/d), C11—C16 (d/s) and C11—C17 (s/d) in a (I)/(IIa)/(IIb) sequence, as well as the already mentioned sp³/sp² character of atom C9 (Scheme 2). These differences lead to the misfit schematically shown in Fig. 2, where the three nuclei have been superposed by forcing the least-squares fit of those atoms not involved in the (s)/(d) bonding issue, viz. C12, C13, C14, C15 and C18.

In order to assess in a more qu­anti­tative way the real significance of these differences in the overall geometry of the `cage' four representative distances are represented in Table 3. Summarizing, they tell us that the eight-membered group in (I) is more `closed' (first entry) and that the `apical' C13 is sensibly leaned toward C16. Even if these differences may seem important, they appear small as compared with the spread of values found in similar 3-aza­bicycles in the literature (Table 3) which confirms that the group is rather flexible irrespective of its apparent closure.

Regarding the supra­molecular structure in (I), there is only one significant inter­molecular inter­action, involving the indole N1—H1N as donor, and hetherocyclic atom N10 as acceptor (Table 4); on the other hand, atom H10N is not involved in any hydrogen bond, as no further acceptor is available in the structure.

The N—H···Nhydrogen bond connects neighbouring molecules into a C(7) chain structure (Bernstein et al., 1995) running along b and built up around the twofold screw axis (Fig. 3a). Incidentally, this pattern is frequently found in compounds crystallizing in the few enanthio­meric space groups with screw axes; as a matter of fact it has also been found in polymorphs (IIa) and (IIb), even cosidering the different space groups (P2₁2₁2₁ versus P2₁) and different synthons (N—H···N versus N—H···O) involved in the inter­action.

These [010] chains are almost non-inter­active, with no mentionable link connecting them short of diffuse dispersion forces. This is observable in Fig. 3(b) (where chains are viewed alongside), and qu­anti­tatively assessed by the rather low packing index of 63.8 (Kitaigorodsky, 1973), as calculated in PLATON (Spek, 2009). As a comparison, packing indices for structures (IIa) and (IIb) are about 4–5% larger, viz. 66.3 for (IIa) and 67.3 for (IIb).

Related literature

For related literature, see: Bernstein et al. (1995); Bhakuni et al. (1976); Bittner et al. (1978); Céspedes et al. (2010); Darbre et al. (1984); Galli et al. (2002); Gribble & Barden (1985); Hesse (1979); Kitaigorodsky (1973); Paz et al. (2013); Spek (2009); Stevens & Kenney (1983); Watson et al. (1989).

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL2013 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of (I), with ellipsoids drawn at the 30% probability level. H atoms are shown with spheres of arbitrary radii.
	Fig. 2. Least-squares superposition of the azabicycles in (I), (IIa) and (IIb), highlighting the differences between them. Atoms used in the fit (circled) are C12, C13, C14, C15 and C18.
	Fig. 3. Packing views of (I), showing (a) the [010] hydrogen-bonded chain, with the hydrogen bonds drawn as broken lines, and (b) a view along b, showing the weakly interacting chains in projection (one of them is highlighted). The broken lines indicate the intra-chain hydrogen bonds.

(1R)-3-[(1S,5S)-(4,4,8-Trimethylbicyclo[3.3.1]non-7-en-2-yl)methyl]-2,3-dihydro-1H-indole

Crystal data

C20H26N2	F(000) = 320
Mr = 294.43	Dx = 1.117 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
a = 9.0358 (5) Å	Cell parameters from 2433 reflections
b = 9.0395 (4) Å	θ = 4.0–23.0°
c = 11.4988 (7) Å	µ = 0.07 mm^−1
β = 111.298 (6)°	T = 294 K
V = 875.07 (9) Å^3	Blocks, colourless
Z = 2	0.30 × 0.18 × 0.18 mm

Data collection

Oxford Diffraction Gemini CCD S Ultra diffractometer	2311 reflections with I > 2σ(I)
ω scans, thick slices	Rint = 0.075
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	θmax = 25.0°, θmin = 3.8°
Tmin = 0.97, Tmax = 0.99	h = −10→10
16112 measured reflections	k = −10→10
3074 independent reflections	l = −13→13

Refinement

Refinement on F^2	3 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.140	w = 1/[σ^2(Fo^2) + (0.096P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.84	(Δ/σ)max < 0.001
3074 reflections	Δρmax = 0.09 e Å^−3
210 parameters	Δρmin = −0.12 e Å^−3

Special details

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.

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

	x	y	z	Uiso*/Ueq
N1	−0.1645 (4)	0.1938 (4)	0.0433 (3)	0.0584 (9)
H1N	−0.218 (5)	0.149 (5)	−0.024 (3)	0.081 (14)*
C2	−0.1002 (4)	0.3316 (5)	0.0468 (3)	0.0550 (10)
H2	−0.1051	0.3858	−0.0232	0.066*
C3	−0.0281 (4)	0.3788 (4)	0.1670 (3)	0.0477 (8)
C3'	−0.0489 (4)	0.2617 (4)	0.2435 (3)	0.0462 (8)
C4	−0.0043 (5)	0.2434 (5)	0.3719 (3)	0.0600 (10)
H4	0.0526	0.3167	0.4266	0.072*
C5	−0.0457 (6)	0.1150 (5)	0.4162 (4)	0.0780 (14)
H5	−0.0153	0.1012	0.5018	0.094*
C6	−0.1319 (6)	0.0059 (5)	0.3354 (4)	0.0788 (14)
H6	−0.1602	−0.0789	0.3682	0.095*
C7	−0.1769 (5)	0.0196 (5)	0.2082 (4)	0.0668 (11)
H7	−0.2337	−0.0547	0.1546	0.080*
C7'	−0.1347 (4)	0.1479 (4)	0.1630 (3)	0.0493 (9)
C8	0.0641 (4)	0.5175 (4)	0.2155 (3)	0.0510 (9)
H8A	0.0298	0.5607	0.2787	0.061*
H8B	0.0423	0.5882	0.1479	0.061*
C9	0.2427 (4)	0.4876 (4)	0.2715 (3)	0.0475 (8)
H9	0.2581	0.3957	0.3197	0.057*
N10	0.3007 (3)	0.4620 (3)	0.1696 (3)	0.0436 (7)
H10N	0.244 (3)	0.392 (3)	0.125 (3)	0.042 (9)*
C11	0.3442 (5)	0.7536 (5)	0.2969 (4)	0.0663 (11)
C12	0.3460 (5)	0.6071 (5)	0.3587 (3)	0.0573 (10)
H12	0.3084	0.6219	0.4277	0.069*
C13	0.5150 (5)	0.5482 (5)	0.4117 (4)	0.0713 (12)
H13A	0.5176	0.4550	0.4543	0.086*
H13B	0.5833	0.6180	0.4712	0.086*
C14	0.5731 (5)	0.5257 (5)	0.3028 (4)	0.0653 (11)
H14	0.6814	0.4861	0.3371	0.078*
C15	0.5809 (6)	0.6782 (6)	0.2469 (5)	0.0865 (14)
H15A	0.6831	0.7226	0.2933	0.104*
H15B	0.5741	0.6654	0.1614	0.104*
C16	0.4536 (6)	0.7811 (5)	0.2483 (5)	0.0801 (14)
H16	0.4504	0.8733	0.2117	0.096*
C17	0.2200 (6)	0.8645 (6)	0.2973 (5)	0.0888 (16)
H17A	0.2421	0.9580	0.2675	0.133*
H17B	0.2216	0.8758	0.3807	0.133*
H17C	0.1172	0.8304	0.2438	0.133*
C18	0.4688 (4)	0.4119 (4)	0.2096 (3)	0.0540 (10)
C19	0.4934 (6)	0.2569 (5)	0.2697 (5)	0.0861 (15)
H19A	0.4283	0.1865	0.2107	0.129*
H19B	0.4644	0.2586	0.3422	0.129*
H19C	0.6030	0.2290	0.2938	0.129*
C20	0.5081 (6)	0.4008 (6)	0.0911 (4)	0.0790 (14)
H20A	0.4782	0.4910	0.0444	0.119*
H20B	0.4506	0.3196	0.0411	0.119*
H20C	0.6200	0.3847	0.1136	0.119*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.052 (2)	0.076 (2)	0.0448 (19)	−0.0122 (18)	0.0153 (15)	−0.0148 (16)
C2	0.044 (2)	0.082 (3)	0.0404 (19)	−0.005 (2)	0.0173 (16)	−0.0005 (18)
C3	0.0378 (18)	0.064 (2)	0.0435 (19)	−0.0044 (17)	0.0175 (15)	−0.0035 (17)
C3'	0.0389 (18)	0.059 (2)	0.0409 (17)	−0.0005 (17)	0.0150 (15)	−0.0061 (17)
C4	0.063 (2)	0.072 (3)	0.0435 (19)	−0.016 (2)	0.0179 (18)	−0.0069 (19)
C5	0.089 (3)	0.088 (3)	0.050 (2)	−0.019 (3)	0.017 (2)	0.012 (2)
C6	0.085 (3)	0.074 (3)	0.065 (3)	−0.020 (3)	0.013 (2)	0.015 (2)
C7	0.060 (3)	0.060 (2)	0.070 (3)	−0.011 (2)	0.011 (2)	−0.004 (2)
C7'	0.0378 (18)	0.063 (2)	0.045 (2)	0.0005 (17)	0.0130 (15)	−0.0043 (17)
C8	0.048 (2)	0.061 (2)	0.0477 (19)	−0.0044 (18)	0.0214 (16)	−0.0017 (16)
C9	0.047 (2)	0.053 (2)	0.0408 (17)	−0.0055 (16)	0.0144 (15)	0.0033 (16)
N10	0.0363 (16)	0.0463 (16)	0.0457 (16)	−0.0041 (13)	0.0119 (12)	−0.0030 (13)
C11	0.065 (3)	0.057 (2)	0.061 (2)	−0.014 (2)	0.005 (2)	−0.018 (2)
C12	0.053 (2)	0.075 (3)	0.0383 (19)	−0.008 (2)	0.0098 (17)	−0.0087 (18)
C13	0.059 (3)	0.089 (3)	0.048 (2)	−0.006 (2)	−0.0032 (19)	0.001 (2)
C14	0.038 (2)	0.074 (3)	0.073 (3)	−0.0051 (19)	0.0080 (19)	0.007 (2)
C15	0.071 (3)	0.074 (3)	0.115 (4)	−0.028 (3)	0.034 (3)	0.002 (3)
C16	0.078 (3)	0.055 (3)	0.095 (3)	−0.023 (2)	0.018 (3)	0.001 (2)
C17	0.089 (4)	0.077 (3)	0.081 (3)	0.006 (3)	0.007 (3)	−0.029 (3)
C18	0.044 (2)	0.056 (2)	0.060 (2)	0.0070 (17)	0.0173 (18)	0.0102 (18)
C19	0.078 (3)	0.065 (3)	0.111 (4)	0.022 (3)	0.030 (3)	0.023 (3)
C20	0.059 (3)	0.100 (4)	0.085 (3)	0.020 (3)	0.035 (2)	0.003 (3)

Geometric parameters (Å, º)

N1—C7'	1.367 (5)	C11—C12	1.500 (6)
N1—C2	1.369 (5)	C11—C17	1.506 (7)
N1—H1N	0.855 (14)	C12—C13	1.520 (6)
C2—C3	1.365 (5)	C12—H12	0.9800
C2—H2	0.9300	C13—C14	1.537 (6)
C3—C3'	1.431 (5)	C13—H13A	0.9700
C3—C8	1.496 (5)	C13—H13B	0.9700
C3'—C4	1.392 (5)	C14—C15	1.533 (6)
C3'—C7'	1.413 (5)	C14—C18	1.536 (5)
C4—C5	1.372 (6)	C14—H14	0.9800
C4—H4	0.9300	C15—C16	1.483 (7)
C5—C6	1.384 (6)	C15—H15A	0.9700
C5—H5	0.9300	C15—H15B	0.9700
C6—C7	1.374 (6)	C16—H16	0.9300
C6—H6	0.9300	C17—H17A	0.9600
C7—C7'	1.380 (6)	C17—H17B	0.9600
C7—H7	0.9300	C17—H17C	0.9600
C8—C9	1.529 (5)	C18—C20	1.531 (6)
C8—H8A	0.9700	C18—C19	1.543 (6)
C8—H8B	0.9700	C19—H19A	0.9600
C9—N10	1.466 (4)	C19—H19B	0.9600
C9—C12	1.537 (5)	C19—H19C	0.9600
C9—H9	0.9800	C20—H20A	0.9600
N10—C18	1.488 (5)	C20—H20B	0.9600
N10—H10N	0.855 (14)	C20—H20C	0.9600
C11—C16	1.324 (7)
C7'—N1—C2	108.7 (3)	C11—C12—H12	108.4
C7'—N1—H1N	128 (3)	C13—C12—H12	108.4
C2—N1—H1N	124 (3)	C9—C12—H12	108.4
C3—C2—N1	110.9 (3)	C12—C13—C14	108.0 (3)
C3—C2—H2	124.6	C12—C13—H13A	110.1
N1—C2—H2	124.6	C14—C13—H13A	110.1
C2—C3—C3'	105.6 (3)	C12—C13—H13B	110.1
C2—C3—C8	129.5 (3)	C14—C13—H13B	110.1
C3'—C3—C8	124.8 (3)	H13A—C13—H13B	108.4
C4—C3'—C7'	119.2 (3)	C15—C14—C18	114.8 (4)
C4—C3'—C3	133.4 (3)	C15—C14—C13	107.7 (4)
C7'—C3'—C3	107.4 (3)	C18—C14—C13	110.6 (3)
C5—C4—C3'	118.8 (3)	C15—C14—H14	107.8
C5—C4—H4	120.6	C18—C14—H14	107.8
C3'—C4—H4	120.6	C13—C14—H14	107.8
C4—C5—C6	121.1 (4)	C16—C15—C14	114.0 (4)
C4—C5—H5	119.5	C16—C15—H15A	108.8
C6—C5—H5	119.5	C14—C15—H15A	108.8
C7—C6—C5	121.8 (4)	C16—C15—H15B	108.8
C7—C6—H6	119.1	C14—C15—H15B	108.8
C5—C6—H6	119.1	H15A—C15—H15B	107.7
C6—C7—C7'	117.5 (4)	C11—C16—C15	126.0 (4)
C6—C7—H7	121.2	C11—C16—H16	117.0
C7'—C7—H7	121.2	C15—C16—H16	117.0
N1—C7'—C7	130.9 (3)	C11—C17—H17A	109.5
N1—C7'—C3'	107.4 (3)	C11—C17—H17B	109.5
C7—C7'—C3'	121.7 (3)	H17A—C17—H17B	109.5
C3—C8—C9	111.6 (3)	C11—C17—H17C	109.5
C3—C8—H8A	109.3	H17A—C17—H17C	109.5
C9—C8—H8A	109.3	H17B—C17—H17C	109.5
C3—C8—H8B	109.3	N10—C18—C20	106.6 (3)
C9—C8—H8B	109.3	N10—C18—C14	108.1 (3)
H8A—C8—H8B	108.0	C20—C18—C14	112.5 (3)
N10—C9—C8	108.7 (3)	N10—C18—C19	112.3 (3)
N10—C9—C12	108.9 (3)	C20—C18—C19	107.3 (4)
C8—C9—C12	116.7 (3)	C14—C18—C19	110.1 (3)
N10—C9—H9	107.4	C18—C19—H19A	109.5
C8—C9—H9	107.4	C18—C19—H19B	109.5
C12—C9—H9	107.4	H19A—C19—H19B	109.5
C9—N10—C18	115.0 (3)	C18—C19—H19C	109.5
C9—N10—H10N	106 (2)	H19A—C19—H19C	109.5
C18—N10—H10N	107 (2)	H19B—C19—H19C	109.5
C16—C11—C12	119.0 (4)	C18—C20—H20A	109.5
C16—C11—C17	123.2 (5)	C18—C20—H20B	109.5
C12—C11—C17	117.8 (4)	H20A—C20—H20B	109.5
C11—C12—C13	109.6 (4)	C18—C20—H20C	109.5
C11—C12—C9	114.3 (3)	H20A—C20—H20C	109.5
C13—C12—C9	107.4 (3)	H20B—C20—H20C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···N10^i	0.85 (4)	2.30 (4)	3.116 (5)	160 (5)

Symmetry code: (i) −x, y−1/2, −z.