Crystal structure of N-[(1S,2S)-2-amino-cyclo-hex-yl]-2,4,6-tri-methyl-benzene-sulfonamide.

The title compound, C15H24N2O2S, was synthesized via a substitution reaction between the enanti-opure (1S,2S)-(+)-1,2-di-amino-cyclo-hexane and 2,4,6-tri-methyl-benzene-1-sulfonyl chloride. The cyclo-hexyl and phenyl substituents are oriented gauche around the sulfonamide S-N bond. In the crystal, mol-ecules are linked via N-H⋯N hydrogen bonds, forming chains propagating along [100].

Chemical context

Many sulfonamides have been reported as anti­cancer, anti-inflammatory, and anti­viral agents (Navia, 2000 ▸; Yan et al., 2006 ▸; Palakurthy & Mandal, 2011 ▸). The use of sulfonamides as catalysts in asymmetric synthesis has also been reported (Lao et al., 2009 ▸; Feng et al., 2010 ▸; Jin et al., 2010 ▸). Through explicit hydrogen-bonding inter­actions with specific functional groups, the electrophilicity and stereoselectivity of a given substrate is enhanced.

Conjugate addition reactions of aldehydes and ketones to nitro­alkenes, catalyzed by chiral primary amines, have been reported (Huang & Jacobsen, 2006 ▸; Rabalakos & Wulff, 2008 ▸; Lao et al., 2009 ▸; Sun et al., 2012 ▸; Zhou et al., 2014 ▸; Ruiz-Olalla et al., 2015 ▸; Yang et al., 2015 ▸). The catalytic activity of chiral primary amine organocatalysts with particular emphasis on the role of the N—H acidity and hydrogen bonding has also been investigated (Lao et al., 2009 ▸). Although the N—H acidity and hydrogen-bonding modes could have an effect on the catalytic activity of the organocatalysts, the nature of the substrate and reaction conditions could be more important. Asymmetric conjugate addition reactions of aldehydes to nitro­alkenes have also been reported as a convenient synthesis of γ-amino acids (Horne & Gellman, 2008 ▸; Wiesner et al., 2008 ▸; Chi et al., 2008 ▸).

In line with our research inter­est in the synthesis of heterogeneous foldamers (Hayen et al., 2004 ▸), we synthesized the title compound as a chiral organocatalyst for conjugate addition. This conjugate addition was then applied for the synthesis of γ-amino acids, which have been shown to be inter­esting foldamer building blocks (Horne & Gellman, 2008 ▸). Therefore, as the title compound is of inter­est in our ongoing effort on foldamer design and synthesis, we report here on the synthesis and crystal structure of this chiral sulfonamide.

Structural commentary

The asymmetric part of the unit cell is shown in Fig. 1 ▸ along with the atom-numbering scheme. The absolute stereochemistry of this chiral sulfonamide was confirmed by a Flack parameter of 0.00 (2) (Parsons et al., 2013 ▸). The cyclo­hexyl (C1–C6) and benzene (C7–C12) substituents are oriented gauche around the sulfonamide S—N bond, with a C1—N1—S1—C7 torsion angle of 70.4 (2)°. A weak intra­molecular inter­action is present between the amine H2A atom and the sp 2-hybridized sulfonamide N1 atom (Table 1 ▸).

Figure 1

The asymmetric part of the unit cell along with the atom-numbering scheme and displacement ellipsoids drawn at the 50% probability level. An intra­molecular N—H⋯N inter­action is shown with a blue dashed line. Only N—H hydrogens are shown for clarity.

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯N1	0.89 (3)	2.43 (3)	2.877 (3)	111 (2)
N1—H1⋯N2i	0.79 (3)	2.14 (3)	2.921 (3)	170 (3)

Symmetry code: (i) .

As described in the Database survey section below, the structure of a racemic crystal of this compound has been reported (FAVHEP; Balsells, et al., 1998 ▸). In this crystal, there are two crystallographically unique mol­ecules of the sulfonamide compound in the asymmetric unit. Here, the cyclo­hexyl and benzene substituents are oriented gauche around the S—N bond with torsion angles of 86.8 (8) and 69.1 (7)°. While we expected that there would be an intra­molecular hydrogen bond in this crystal, in the model deposited in the CSD there are no intra­molecular hydrogen bonds present between the amine N—H group and the sulfonamide N atom.

Supra­molecular features

Mol­ecules of the title compound are held together in the solid state by inter­molecular hydrogen-bonding inter­actions between the donor sulfonamide N1—H1 and the acceptor amine N2 atoms (Table 1 ▸ and Fig. 2 ▸). These hydrogen bonds arrange mol­ecules into supra­molecular chains that are oriented along the [100] axis (Fig. 2 ▸). Weaker N2—H2B⋯O1(1 + x, y, z) inter­actions with an H2B⋯O1(1 + x, y, z) distance of 2.72 Å between the donor amine N2—H2B and the acceptor sulfonamide O1 atoms can also be noticed within this chain.

Figure 2

Intra- and inter­molecular hydrogen-bonding inter­actions present in the crystal. Hydrogen bonds are drawn as blue dashed lines. Only N—H hydrogens are shown for clarity. [Symmetry code: (i) x − , −y + , −z + 1.]

As for the racemic crystal FAVHEP, in the model deposited in the CSD there is one inter­molecular hydrogen bond present between a donor sulfonamide N1—H1 and a nearby amine acceptor N atom [D⋯H = 0.860 (7) Å; H⋯A = 2.160 (8) Å; D⋯A = 3.011 (8) Å; D—H⋯A = 169.9 (5)°].

Database survey

The Cambridge Structural Database (CSD, Version 5.36, May 2015; Groom & Allen, 2014 ▸) contains 35 sulfonamides bearing a mesitylene group on the S atom. Of these, there are four structures where the substituent bonded to the sulfonamide N atom is an aliphatic six-membered ring. In structures RAWMAF (Hou et al., 2012 ▸) and ZIQPAS (Wu et al., 2014 ▸), the amino­cyclo­hexane substituent is part of a larger fused-ring system. Inter­estingly, there are two structures with 1,2-di­amino­cyclo­hexane rings as the amide substituent. In structure OTOPAP (Schwarz et al., 2010 ▸), both amines of the trans-1,2-di­amino­cyclo­hexane ring are bonded to a mesitylsulfonamide group. Structure FAVHEP (Balsells et al., 1998 ▸) is the same as the title compound, but is present as a racemic mixture that crystallized in the space group P .

Synthesis and crystallization

To a stirred solution of (1S,2S)-(+)-1,2-di­amino­cyclo­hexane (0.77 g, 6.74 mmol) in 5 ml of CH2Cl2 at 273 K was added a solution of 2,4,6-tri­methyl­benzene-1-sulfonyl chloride (0.44 g, 2.01 mmol) in 5 ml CH2Cl2. After the addition was complete (20 min), the mixture was allowed to warm to room temperature and stirred overnight. The reaction mixture was washed with H2O (3 × 25 ml) and the aqueous layer was back-extracted with CH2Cl2 (20 ml). The combined organic extracts were dried over Na2SO4 and the solvent was removed under reduced pressure. The residue was purified by column chromatography over silica gel (CH2Cl2/EtOAc 1:1 v/v) to afford a pale-yellow–white solid (yield: 0.46 g, 78%). Part of the purified product was redissolved in CH2Cl2 and after slow evaporation for several days, white large chunky crystals (stained yellow) were formed that were suitable for analysis by X-ray diffraction (m.p. 406–407 K).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The positions of all non-polar H atoms were calculated geometrically and refined to ride on their parent atoms, with U iso(H) = 1.2U eq(C) for methine, methyl­ene and aryl groups, and U iso(H) = 1.5U eq(C) for methyl groups. H atoms bonded directly to N atoms (H1, H2A and H2B) were located in difference-Fourier maps and refined isotropically.

Table 2

Experimental details

Crystal data
Chemical formula	C15H24N2O2S
M r	296.42
Crystal system, space group	Orthorhombic, P212121
Temperature (K)	173
a, b, c (Å)	6.5215 (4), 10.0202 (6), 23.3660 (15)
V (Å3)	1526.89 (16)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.22
Crystal size (mm)	0.37 × 0.20 × 0.15
Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2014 ▸)
T min, T max	0.706, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	25587, 2799, 2667
R int	0.034
(sin θ/λ)max (Å−1)	0.602
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.029, 0.071, 1.06
No. of reflections	2799
No. of parameters	196
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.19, −0.21
Absolute structure	Flack parameter x determined using 1098 quotients [(I +)−(I −)]/[(I +)+(I −)] (Parsons et al., 2013 ▸)
Absolute structure parameter	0.00 (2)

Computer programs: APEX2 ad SAINT (Bruker, 2013 ▸), SHELXS97 (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), OLEX2 (Dolomanov et al., 2009 ▸; Bourhis et al., 2015 ▸) and CrystalMaker (Palmer, 2007 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S205698901502191X/gk2646sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S205698901502191X/gk2646Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S205698901502191X/gk2646Isup3.cml

CCDC reference: 1437453

Additional supporting information: crystallographic information; 3D view; checkCIF report

C15H24N2O2S	Dx = 1.289 Mg m−3
Mr = 296.42	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 9968 reflections
a = 6.5215 (4) Å	θ = 2.2–25.3°
b = 10.0202 (6) Å	µ = 0.22 mm−1
c = 23.3660 (15) Å	T = 173 K
V = 1526.89 (16) Å3	Block, colourless
Z = 4	0.37 × 0.20 × 0.15 mm
F(000) = 640

Bruker APEXII CCD diffractometer	2799 independent reflections
Radiation source: sealed tube	2667 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 8 pixels mm-1	θmax = 25.4°, θmin = 1.7°
φ and ω scans	h = −7→7
Absorption correction: multi-scan (SADABS; Bruker, 2014)	k = −12→12
Tmin = 0.706, Tmax = 0.745	l = −28→28
25587 measured reflections

Refinement on F2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.029	w = 1/[σ2(Fo2) + (0.0313P)2 + 0.5049P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.071	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.19 e Å−3
2799 reflections	Δρmin = −0.21 e Å−3
196 parameters	Absolute structure: Flack parameter x determined using 1098 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
0 restraints	Absolute structure parameter: 0.00 (2)

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.

	x	y	z	Uiso*/Ueq
S1	0.39425 (9)	0.81200 (6)	0.62892 (2)	0.03018 (16)
O1	0.2464 (3)	0.72704 (19)	0.65596 (8)	0.0412 (4)
O2	0.3238 (3)	0.93797 (17)	0.60697 (8)	0.0408 (5)
N1	0.5015 (3)	0.7361 (2)	0.57616 (9)	0.0297 (5)
N2	0.9140 (3)	0.6769 (2)	0.54061 (8)	0.0287 (4)
C1	0.5776 (3)	0.5984 (2)	0.58084 (9)	0.0238 (5)
H1A	0.6425	0.5872	0.6193	0.029*
C2	0.7442 (3)	0.5816 (2)	0.53502 (9)	0.0234 (5)
H2	0.6780	0.5986	0.4971	0.028*
C3	0.8271 (3)	0.4398 (2)	0.53360 (10)	0.0273 (5)
H3A	0.9052	0.4225	0.5692	0.033*
H3B	0.9228	0.4306	0.5009	0.033*
C4	0.6574 (4)	0.3363 (2)	0.52793 (10)	0.0308 (5)
H4A	0.7174	0.2457	0.5300	0.037*
H4B	0.5902	0.3460	0.4902	0.037*
C5	0.4980 (4)	0.3528 (2)	0.57518 (11)	0.0314 (5)
H5A	0.3864	0.2871	0.5696	0.038*
H5B	0.5624	0.3353	0.6128	0.038*
C6	0.4094 (4)	0.4934 (2)	0.57442 (10)	0.0300 (5)
H6A	0.3095	0.5031	0.6061	0.036*
H6B	0.3356	0.5080	0.5379	0.036*
C7	0.5988 (4)	0.8413 (2)	0.67770 (9)	0.0252 (5)
C8	0.7523 (4)	0.9336 (2)	0.66163 (9)	0.0270 (5)
C9	0.9071 (4)	0.9619 (2)	0.69984 (10)	0.0321 (5)
H9	1.0119	1.0225	0.6887	0.039*
C10	0.9154 (4)	0.9054 (2)	0.75383 (10)	0.0340 (6)
C11	0.7662 (4)	0.8131 (3)	0.76822 (10)	0.0346 (5)
H11	0.7724	0.7723	0.8049	0.042*
C12	0.6078 (4)	0.7775 (2)	0.73148 (9)	0.0291 (5)
C13	0.7568 (5)	1.0087 (2)	0.60541 (10)	0.0384 (6)
H13A	0.7084	0.9502	0.5746	0.058*
H13B	0.8974	1.0373	0.5972	0.058*
H13C	0.6675	1.0871	0.6080	0.058*
C14	1.0799 (5)	0.9459 (3)	0.79566 (13)	0.0532 (8)
H14A	1.2117	0.9523	0.7757	0.080*
H14B	1.0897	0.8789	0.8261	0.080*
H14C	1.0452	1.0327	0.8124	0.080*
C15	0.4607 (5)	0.6726 (3)	0.75300 (12)	0.0440 (7)
H15A	0.3236	0.7116	0.7569	0.066*
H15B	0.5071	0.6399	0.7903	0.066*
H15C	0.4559	0.5983	0.7258	0.066*
H2A	0.864 (5)	0.754 (3)	0.5537 (12)	0.047 (8)*
H1	0.484 (5)	0.768 (3)	0.5458 (13)	0.040 (8)*
H2B	1.003 (5)	0.645 (3)	0.5683 (13)	0.045 (8)*

	U11	U22	U33	U12	U13	U23
S1	0.0271 (3)	0.0327 (3)	0.0307 (3)	0.0072 (3)	0.0005 (3)	−0.0065 (2)
O1	0.0275 (8)	0.0496 (11)	0.0465 (10)	−0.0037 (8)	0.0092 (8)	−0.0111 (8)
O2	0.0427 (10)	0.0387 (10)	0.0410 (10)	0.0196 (8)	−0.0057 (8)	−0.0067 (8)
N1	0.0371 (11)	0.0293 (11)	0.0228 (10)	0.0109 (9)	−0.0014 (9)	−0.0010 (9)
N2	0.0283 (10)	0.0250 (10)	0.0329 (10)	−0.0021 (9)	0.0002 (9)	−0.0004 (9)
C1	0.0239 (11)	0.0250 (11)	0.0225 (10)	0.0044 (9)	−0.0012 (9)	−0.0009 (9)
C2	0.0228 (10)	0.0238 (11)	0.0236 (10)	0.0009 (9)	0.0001 (9)	0.0016 (9)
C3	0.0261 (11)	0.0259 (12)	0.0300 (12)	0.0053 (10)	0.0036 (9)	0.0003 (9)
C4	0.0357 (13)	0.0241 (11)	0.0326 (12)	0.0008 (10)	0.0001 (10)	−0.0010 (9)
C5	0.0315 (13)	0.0313 (13)	0.0315 (12)	−0.0059 (10)	0.0014 (10)	0.0010 (10)
C6	0.0229 (11)	0.0359 (12)	0.0312 (11)	−0.0006 (11)	0.0032 (11)	−0.0033 (10)
C7	0.0278 (11)	0.0242 (10)	0.0235 (10)	0.0038 (10)	0.0040 (10)	−0.0040 (8)
C8	0.0327 (12)	0.0217 (11)	0.0267 (11)	0.0030 (10)	0.0081 (10)	−0.0020 (9)
C9	0.0291 (12)	0.0290 (12)	0.0382 (13)	−0.0015 (11)	0.0069 (12)	−0.0045 (10)
C10	0.0319 (13)	0.0361 (13)	0.0340 (13)	0.0076 (11)	−0.0008 (11)	−0.0102 (10)
C11	0.0465 (14)	0.0342 (12)	0.0232 (11)	0.0075 (13)	0.0014 (11)	0.0010 (10)
C12	0.0367 (12)	0.0247 (11)	0.0259 (11)	0.0018 (11)	0.0062 (11)	−0.0010 (9)
C13	0.0536 (16)	0.0285 (12)	0.0331 (13)	−0.0021 (12)	0.0098 (13)	0.0058 (11)
C14	0.0455 (18)	0.0629 (19)	0.0512 (17)	0.0037 (16)	−0.0124 (16)	−0.0140 (15)
C15	0.0569 (18)	0.0351 (14)	0.0401 (14)	−0.0079 (13)	0.0094 (13)	0.0066 (12)

S1—O1	1.4330 (19)	C6—H6A	0.9900
S1—O2	1.4379 (18)	C6—H6B	0.9900
S1—N1	1.609 (2)	C7—C8	1.414 (3)
S1—C7	1.779 (2)	C7—C12	1.411 (3)
N1—C1	1.470 (3)	C8—C9	1.377 (3)
N1—H1	0.79 (3)	C8—C13	1.514 (3)
N2—C2	1.469 (3)	C9—H9	0.9500
N2—H2A	0.89 (3)	C9—C10	1.384 (3)
N2—H2B	0.93 (3)	C10—C11	1.384 (4)
C1—H1A	1.0000	C10—C14	1.507 (4)
C1—C2	1.535 (3)	C11—H11	0.9500
C1—C6	1.527 (3)	C11—C12	1.390 (4)
C2—H2	1.0000	C12—C15	1.509 (3)
C2—C3	1.521 (3)	C13—H13A	0.9800
C3—H3A	0.9900	C13—H13B	0.9800
C3—H3B	0.9900	C13—H13C	0.9800
C3—C4	1.522 (3)	C14—H14A	0.9800
C4—H4A	0.9900	C14—H14B	0.9800
C4—H4B	0.9900	C14—H14C	0.9800
C4—C5	1.525 (3)	C15—H15A	0.9800
C5—H5A	0.9900	C15—H15B	0.9800
C5—H5B	0.9900	C15—H15C	0.9800
C5—C6	1.523 (3)
O1—S1—O2	117.62 (12)	C1—C6—H6A	109.4
O1—S1—N1	110.46 (11)	C1—C6—H6B	109.4
O1—S1—C7	108.68 (11)	C5—C6—C1	111.33 (19)
O2—S1—N1	106.31 (11)	C5—C6—H6A	109.4
O2—S1—C7	108.86 (11)	C5—C6—H6B	109.4
N1—S1—C7	104.06 (11)	H6A—C6—H6B	108.0
S1—N1—H1	116 (2)	C8—C7—S1	117.96 (16)
C1—N1—S1	122.24 (17)	C12—C7—S1	121.78 (19)
C1—N1—H1	120 (2)	C12—C7—C8	120.2 (2)
C2—N2—H2A	108 (2)	C7—C8—C13	124.7 (2)
C2—N2—H2B	108.1 (18)	C9—C8—C7	118.8 (2)
H2A—N2—H2B	107 (3)	C9—C8—C13	116.5 (2)
N1—C1—H1A	108.4	C8—C9—H9	118.8
N1—C1—C2	106.87 (18)	C8—C9—C10	122.4 (2)
N1—C1—C6	113.39 (19)	C10—C9—H9	118.8
C2—C1—H1A	108.4	C9—C10—C14	120.6 (3)
C6—C1—H1A	108.4	C11—C10—C9	117.9 (2)
C6—C1—C2	111.36 (17)	C11—C10—C14	121.5 (2)
N2—C2—C1	113.59 (18)	C10—C11—H11	118.5
N2—C2—H2	107.1	C10—C11—C12	123.0 (2)
N2—C2—C3	109.98 (18)	C12—C11—H11	118.5
C1—C2—H2	107.1	C7—C12—C15	125.9 (2)
C3—C2—C1	111.70 (18)	C11—C12—C7	117.7 (2)
C3—C2—H2	107.1	C11—C12—C15	116.5 (2)
C2—C3—H3A	109.1	C8—C13—H13A	109.5
C2—C3—H3B	109.1	C8—C13—H13B	109.5
C2—C3—C4	112.32 (19)	C8—C13—H13C	109.5
H3A—C3—H3B	107.9	H13A—C13—H13B	109.5
C4—C3—H3A	109.1	H13A—C13—H13C	109.5
C4—C3—H3B	109.1	H13B—C13—H13C	109.5
C3—C4—H4A	109.4	C10—C14—H14A	109.5
C3—C4—H4B	109.4	C10—C14—H14B	109.5
C3—C4—C5	111.02 (19)	C10—C14—H14C	109.5
H4A—C4—H4B	108.0	H14A—C14—H14B	109.5
C5—C4—H4A	109.4	H14A—C14—H14C	109.5
C5—C4—H4B	109.4	H14B—C14—H14C	109.5
C4—C5—H5A	109.5	C12—C15—H15A	109.5
C4—C5—H5B	109.5	C12—C15—H15B	109.5
H5A—C5—H5B	108.1	C12—C15—H15C	109.5
C6—C5—C4	110.51 (19)	H15A—C15—H15B	109.5
C6—C5—H5A	109.5	H15A—C15—H15C	109.5
C6—C5—H5B	109.5	H15B—C15—H15C	109.5
S1—N1—C1—C2	−156.04 (17)	C2—C1—C6—C5	55.2 (2)
S1—N1—C1—C6	80.9 (2)	C2—C3—C4—C5	−55.0 (3)
S1—C7—C8—C9	177.22 (17)	C3—C4—C5—C6	56.8 (3)
S1—C7—C8—C13	−0.7 (3)	C4—C5—C6—C1	−57.3 (3)
S1—C7—C12—C11	−175.90 (18)	C6—C1—C2—N2	−177.74 (19)
S1—C7—C12—C15	4.4 (3)	C6—C1—C2—C3	−52.6 (2)
O1—S1—N1—C1	−46.1 (2)	C7—S1—N1—C1	70.4 (2)
O1—S1—C7—C8	−173.93 (17)	C7—C8—C9—C10	−1.4 (3)
O1—S1—C7—C12	4.7 (2)	C8—C7—C12—C11	2.7 (3)
O2—S1—N1—C1	−174.73 (18)	C8—C7—C12—C15	−177.0 (2)
O2—S1—C7—C8	−44.7 (2)	C8—C9—C10—C11	2.8 (4)
O2—S1—C7—C12	133.97 (19)	C8—C9—C10—C14	−176.1 (2)
N1—S1—C7—C8	68.36 (19)	C9—C10—C11—C12	−1.4 (4)
N1—S1—C7—C12	−112.99 (19)	C10—C11—C12—C7	−1.3 (4)
N1—C1—C2—N2	57.9 (2)	C10—C11—C12—C15	178.4 (2)
N1—C1—C2—C3	−176.97 (18)	C12—C7—C8—C9	−1.5 (3)
N1—C1—C6—C5	175.8 (2)	C12—C7—C8—C13	−179.4 (2)
N2—C2—C3—C4	179.90 (18)	C13—C8—C9—C10	176.7 (2)
C1—C2—C3—C4	52.8 (3)	C14—C10—C11—C12	177.4 (2)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···N1	0.89 (3)	2.43 (3)	2.877 (3)	111 (2)
N1—H1···N2i	0.79 (3)	2.14 (3)	2.921 (3)	170 (3)