Synthesis, crystal structure and Hirshfeld surface analysis of bis­(caffeinium) hexa­chlorido­platinum(IV) in comparison with some related compounds

Zagidullin, K.A.; Novikov, A.P.; Zelenina, D.A.; Grigoriev, M.S.; German, K.E.

doi:10.1107/S2056989023005157

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ISSN: 2056-9890

Volume 79| Part 7| July 2023| Pages 644-647

https://doi.org/10.1107/S2056989023005157

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Synthesis, crystal structure and Hirshfeld surface analysis of bis(caffeinium) hexachloridoplatinum(IV) in comparison with some related compounds

Karim A. Zagidullin,^a Anton P. Novikov,^a,^b Daria A. Zelenina,^a,^c ^* Mikhail S. Grigoriev ^a and Konstantin E. German ^a

^aFrumkin Institute of Physical Chemistry and Electrochemistry Russian, Academy, of Sciences, 31 Leninsky Prospekt bldg 4, 119071 Moscow, Russian Federation, ^bPeoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya, St, 117198, Moscow, Russian Federation, and ^cKyrgyz-Russian Slavic University, 6 Chuy Avenue, Bishkek, Kyrgyzstan
^*Correspondence e-mail: den-taranee.92@mail.ru

Edited by A. S. Batsanov, University of Durham, United Kingdom (Received 14 April 2023; accepted 8 June 2023; online 16 June 2023)

The molecular and crystal structure of the title compound, (C₈H₁₁N₄O₂)₂[PtCl₆], synthesized from hexachloroplatinic acid and caffeine in methanol, was studied by single-crystal X-ray diffraction. The caffeinium cations form a double layer via hydrogen bonds and π-stacking interactions. The Hirshfeld surface analysis showed that the largest contribution to the crystal packing is made by H⋯H (31.2%), H⋯Cl/Cl⋯H (22.6%), O⋯H/H⋯O (21.9%) contacts for the cation and H⋯Cl/Cl⋯H (79.3%) contacts for the anion.

Keywords: crystal structure; platinum; Pt; caffeine; Hirshfeld surface analysis; hexahalide; π-stacking.

CCDC reference: 2268577

1. Chemical context

Caffeine is a biologically active compound involved in a number of biochemical processes (Costa et al., 2010 ; Santos et al., 2010 ; Herman & Herman, 2012 ). Some sources consider it the most common medicine in the world, constantly used by the population (Knapik et al., 2022 ). It is known that caffeine compounds are able to exert a strong influence on the action of various pharmaceutical drugs (Traganos et al., 1991 ). Currently, an active search is underway for platinum-based pharmaceutical drugs, primarily those with antitumor activity (Dilruba & Kalayda, 2016 ). In this regard, it seemed important to us to study the interaction of caffeine with the chemical forms of platinum used in the pharmaceutical industry. In addition, platinum is actively used as a catalyst in chemical reactions, including various fields of fine organic synthesis (Blaser & Studer, 2007 ; Zhang et al., 2006 ; Seselj et al., 2015 ). Study of interaction of Pt^IV with various heterocyclic organic molecules is of great importance in the context of search for new catalytic reactions and synthetic routes. Studies on the interaction of hexachloroplatinates with various biological organic compounds have been performed before, for example by Novikov et al. (2021 , 2022 ).

In this work, the title compound I containing [PtCl₆]²⁻ anions and caffeinium cations was synthesized by the reaction of caffeine with H₂[PtCl₆] in methanol and structurally characterized, using Hirshfeld surface analysis to estimate relative contribution of non-covalent intermolecular interactions in comparison with similar compounds, bis(3-carboxypyridinium) hexachloroplatinum RECJAO (II; Novikov et al., 2022) and methylcaffeinium hexafluorophospate AXUQIT (III; Kascatan-Nebioglu et al., 2004 ).

2. Structural commentary

Compound I (Fig.1a) crystallizes in the triclinic space group P $[\overline{1}]$ . The unit cell (Fig. 1b) contains two caffeinium cations and one centrosymmetric hexachloroplatinate anion with a platinum atom in a special position 1a. In the imidazole ring of the caffeine molecule, the nitrogen N1 atom is protonated. The cation, including the methyl groups, has a flat geometry (maximum deviation for non-hydrogen atoms 0.030 Å). The [PtCl₆]²⁻ anion has a slightly distorted octahedral geometry with similar Pt—Cl bond distances (Table 1).

Table 1
Selected geometric parameters (Å, °)

Pt1—Cl1	2.3153 (6)	Pt1—Cl3	2.3222 (6)
Pt1—Cl2	2.3161 (6)

Cl1—Pt1—Cl2	89.97 (2)	Cl1ⁱ—Pt1—Cl3	89.93 (2)
Cl1ⁱ—Pt1—Cl2	90.03 (2)	Cl2ⁱ—Pt1—Cl3ⁱ	89.48 (3)
Cl1—Pt1—Cl3	90.07 (2)	Cl2—Pt1—Cl3ⁱ	90.52 (3)
Symmetry code: (i) .

Figure 1
(a) Molecular structure of the title compound and (b) the unit cell with π-stacking interactions [symmetry code: (i) −x, −y, −z].

3. Supramolecular features

Hydrogen bonds and π-stacking play a significant role in the formation of intermolecular interactions in the crystal structure of I. π-stacking is observed between the six-membered pyrimidine rings. Pairs of parallel cations related by an inversion centre, are stacked with interplanar separation of 3.404 (3) Å (Fig. 1b).

Similarly, π–halogen interactions (Lucas et al., 2016 ; Savastano et al., 2018 ; Frontera et al., 2011 ; Novikov et al., 2022) are found between the aromatic ring C6/N4/C8/N3/C2/C1 (centroid Cz) and chlorine atoms Cl1 and Cl2, with Cz ⋯ Cl distances of 3.8643 (11) and 3.7170 (11) Å, respectively, and α angles between the ring plane and the Cz⋯Cl vector of 61.82 (7) and 62.28 (7)°, respectively. It is uncertain whether such an interaction exists with Cl3 [Cz⋯Cl = 4.1102 (12) Å, α = 58.68 (8)°].

The crystal packing in I can be represented as cationic and anionic layers parallel to the (001) plane (Fig. 2). The caffeinium cations are linked by π-stacking interactions and weak C—H⋯O hydrogen bonds into double layers, which are connected to the anionic layers by hydrogen bonds of the N—H⋯Cl and C—H⋯C types (Table 2), the N1—H1⋯Cl3ⁱⁱ [symmetry code: (ii) −x + 1, −y + 1, −z] interaction being the strongest.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Cl3ⁱⁱ	0.85 (2)	2.45 (2)	3.296 (2)	174 (3)
C3—H3⋯Cl2ⁱⁱ	0.89 (3)	2.81 (3)	3.455 (3)	131 (3)
C5—H5C⋯Cl2	0.96	2.91	3.563 (3)	127
C7—H7B⋯O1ⁱⁱⁱ	0.96	2.44	3.346 (4)	157
Symmetry codes: (ii) ; (iii) .

Figure 2
Crystal packing of I, showing the pseudo-layered character.

4. Hirshfeld surface analysis

Crystal Explorer 21 was used to calculate the Hirshfeld surfaces (HS) and two-dimensional fingerprint plots (Figs. 3 and 4). The donor and acceptor groups are visualized using a standard (high) surface resolution and d_norm surfaces are mapped over a fixed colour scale of −0.401 (red) to 1.063 (blue) for cation and −0.402 to 0.934 a.u. for anion, as illustrated in Fig. 3. Additionally, characteristic red and blue triangles indicative of π-stacking interactions are observed on the shape-index surface (Fig. 3b).

Figure 3
Hirshfeld surface of the caffeinium cation mapped over (a) d_norm and (b) shape-index.

Figure 4
Two-dimensional fingerprint plots for the cations and anions in I.

Analysis of intermolecular contacts shows that for the caffeinum cation, the largest contributions are made by H⋯H, Cl⋯H/H⋯Cl and O⋯H/H⋯O contacts (Fig. 5), and for the anion, by Cl⋯H/H⋯Cl and Cl⋯C/C⋯Cl contacts (Fig. 6). Whereas H⋯H contacts correspond to van der Waals interactions, O⋯H and Cl⋯H contacts can be described as weak hydrogen bonds. Typically, hydrogen bonds are revealed by characteristic discrete `spikes' in the fingerprint plots – indeed, such features can be observed in Fig. 4c,d,i. The structures of II and III show distributions of contacts (Figs. 5 and 6) broadly similar to that of I, if corrected for the different cation–anion ratios (1:1 for I and III, 2:1 for II).

Figure 5
Percentage contributions of intermolecular interactions for the cations in I and similar compounds.

Figure 6
Percentage contributions of intermolecular interactions for the anions in I and similar compounds.

5. Database survey

A search of the Cambridge Structural Database (CSD, Version 5.43, update of November 2022; Groom et al., 2016 ) revealed 13 unique structures with caffeinium cations, but none of them contained anions of MHal₆ type. The closest analogues of I found were II and III (see above), the former containing N-protonated 3-carboxypyridine (nicotinic acid) as the cation and [PtCl₆]²⁻ as the anion, the latter containing a caffeinium cation with a methylated (rather than protonated) N1 atom and a PF₆⁻ anion.

6. Synthesis and crystallization

A saturated solution of dried caffeine in 5 mL of methanol was prepared, to which a few drops of a concentrated solution of hexachloroplatinic acid in hydrochloric acid were added. After one week, the yellow crystals of I that formed were extracted from the solution.

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. Reflections with resolution > 5 Å, obscured by the beamstop (beam diameter 0.6 mm), were excluded from the refinement. The methyl groups C5H₃ and C7H₃ were refined as rigid bodies rotating around N—C bonds [U_iso(H) refined], C4H₃ as rotationally disordered between two orientations with occupancies of 0.62 (4) and 0.38 (4) [U_iso(H) = 1.2U_eq(C)], with C—H 0.96 Å in each case. The H atoms at N1 and C3 were refined isotropically.

Table 3
Experimental details

Crystal data
Chemical formula	(C₈H₁₁N₄O₂)₂[PtCl₆]
M_r	798.20
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	296
a, b, c (Å)	7.8800 (2), 8.1542 (2), 10.5374 (3)
α, β, γ (°)	95.784 (2), 91.525 (2), 112.472 (1)
V (Å³)	620.92 (3)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	6.34
Crystal size (mm)	0.18 × 0.08 × 0.02

Data collection
Diffractometer	Bruker Kappa APEXII area-detector
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.734, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	9764, 3616, 3573
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.022, 0.041, 1.04
No. of reflections	3616
No. of parameters	173
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)	0.45, −0.89
Computer programs: APEX3 (Bruker, 2018 ), SAINT (Bruker, 2013 ), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 2268577

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989023005157/zv2027sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989023005157/zv2027Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2018); cell refinement: SAINT v7.68A (Bruker, 2013); data reduction: SAINT v7.68A (Bruker, 2013); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: Olex2 1.5 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 1.5 (Dolomanov et al., 2009).

Bis(1,3,7-trimethyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-9-ium) hexachloridoplatinum(IV) top

Crystal data top

(C₈H₁₁N₄O₂)₂[PtCl₆]	Z = 1
M_r = 798.20	F(000) = 386
Triclinic, P1	D_x = 2.135 Mg m⁻³
a = 7.8800 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.1542 (2) Å	Cell parameters from 4212 reflections
c = 10.5374 (3) Å	θ = 3.1–29.8°
α = 95.784 (2)°	µ = 6.34 mm⁻¹
β = 91.525 (2)°	T = 296 K
γ = 112.472 (1)°	Plate, orange
V = 620.92 (3) Å³	0.18 × 0.08 × 0.02 mm

Data collection top

Bruker Kappa APEXII area-detector diffractometer	3573 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.035
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 30.0°, θ_min = 3.5°
T_min = 0.734, T_max = 1.000	h = −11→11
9764 measured reflections	k = −11→11
3616 independent reflections	l = −14→14

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.022	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.041	w = 1/[σ²(F_o²) + (0.0171P)²] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3616 reflections	Δρ_max = 0.45 e Å⁻³
173 parameters	Δρ_min = −0.89 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.

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Pt1	0.000000	0.000000	0.000000	0.02050 (4)
Cl1	−0.04784 (10)	0.01026 (9)	0.21599 (5)	0.03560 (15)
Cl2	0.30304 (9)	0.03978 (10)	0.04685 (6)	0.03557 (14)
Cl3	0.08989 (10)	0.30803 (8)	0.01376 (6)	0.03532 (14)
O1	0.5394 (3)	0.1187 (3)	0.3683 (2)	0.0474 (5)
O2	0.1510 (3)	0.4010 (3)	0.4685 (2)	0.0517 (6)
N1	0.5642 (3)	0.6187 (3)	0.1713 (2)	0.0340 (5)
H1	0.656 (3)	0.646 (4)	0.126 (3)	0.053 (10)*
N2	0.3378 (3)	0.6487 (3)	0.2696 (2)	0.0317 (5)
N3	0.5758 (3)	0.3628 (3)	0.2700 (2)	0.0296 (5)
N4	0.3502 (3)	0.2641 (3)	0.42037 (19)	0.0289 (5)
C1	0.3648 (4)	0.5055 (3)	0.3126 (2)	0.0271 (5)
C2	0.5073 (4)	0.4880 (3)	0.2510 (2)	0.0269 (5)
C3	0.4589 (4)	0.7135 (4)	0.1859 (3)	0.0378 (7)
H3	0.475 (4)	0.812 (4)	0.150 (3)	0.046 (9)*
C4	0.1984 (5)	0.7171 (4)	0.3115 (3)	0.0485 (8)
H4A	0.127241	0.645910	0.373253	0.058*	0.38 (4)
H4B	0.258237	0.838989	0.349513	0.058*	0.38 (4)
H4C	0.118735	0.711220	0.239191	0.058*	0.38 (4)
H4D	0.208901	0.818169	0.268052	0.058*	0.62 (4)
H4E	0.077905	0.625090	0.291792	0.058*	0.62 (4)
H4F	0.217407	0.752859	0.402113	0.058*	0.62 (4)
C5	0.7299 (4)	0.3460 (4)	0.2023 (3)	0.0461 (8)
H5A	0.817041	0.334293	0.262454	0.097 (9)*
H5B	0.788825	0.450488	0.160388	0.097 (9)*
H5C	0.684455	0.242150	0.139850	0.097 (9)*
C6	0.2746 (4)	0.3915 (3)	0.4059 (2)	0.0306 (5)
C7	0.2650 (4)	0.1360 (4)	0.5105 (3)	0.0387 (7)
H7A	0.226895	0.194389	0.581227	0.051 (5)*
H7B	0.352395	0.090814	0.541266	0.051 (5)*
H7C	0.159753	0.038818	0.468151	0.051 (5)*
C8	0.4901 (4)	0.2398 (4)	0.3536 (2)	0.0312 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.02068 (7)	0.02260 (7)	0.01919 (6)	0.00823 (5)	0.00384 (4)	0.00678 (4)
Cl1	0.0415 (4)	0.0448 (4)	0.0214 (3)	0.0164 (3)	0.0078 (2)	0.0081 (2)
Cl2	0.0232 (3)	0.0458 (4)	0.0396 (3)	0.0136 (3)	0.0015 (2)	0.0125 (3)
Cl3	0.0420 (4)	0.0236 (3)	0.0410 (3)	0.0114 (3)	0.0123 (3)	0.0088 (2)
O1	0.0488 (13)	0.0419 (12)	0.0622 (14)	0.0242 (11)	0.0122 (10)	0.0258 (10)
O2	0.0584 (15)	0.0519 (14)	0.0569 (13)	0.0294 (12)	0.0344 (11)	0.0201 (11)
N1	0.0342 (13)	0.0317 (12)	0.0351 (12)	0.0088 (10)	0.0109 (10)	0.0131 (9)
N2	0.0337 (12)	0.0253 (11)	0.0357 (11)	0.0106 (10)	0.0019 (9)	0.0054 (9)
N3	0.0285 (12)	0.0289 (11)	0.0327 (11)	0.0110 (9)	0.0066 (9)	0.0085 (8)
N4	0.0331 (12)	0.0278 (11)	0.0258 (10)	0.0103 (9)	0.0052 (8)	0.0090 (8)
C1	0.0280 (13)	0.0218 (12)	0.0303 (12)	0.0079 (10)	0.0015 (10)	0.0040 (9)
C2	0.0288 (13)	0.0236 (12)	0.0251 (11)	0.0062 (10)	0.0009 (9)	0.0049 (9)
C3	0.0453 (18)	0.0281 (14)	0.0393 (15)	0.0110 (13)	0.0048 (12)	0.0129 (11)
C4	0.0430 (18)	0.0396 (18)	0.071 (2)	0.0243 (15)	0.0078 (16)	0.0092 (15)
C5	0.0368 (17)	0.0457 (18)	0.062 (2)	0.0201 (14)	0.0206 (14)	0.0134 (15)
C6	0.0328 (14)	0.0288 (13)	0.0283 (12)	0.0097 (11)	0.0043 (10)	0.0033 (10)
C7	0.0433 (17)	0.0378 (16)	0.0320 (13)	0.0087 (13)	0.0098 (12)	0.0172 (11)
C8	0.0290 (14)	0.0296 (14)	0.0329 (13)	0.0081 (11)	0.0001 (10)	0.0082 (10)

Geometric parameters (Å, º) top

Pt1—Cl1ⁱ	2.3153 (6)	N4—C7	1.464 (3)
Pt1—Cl1	2.3153 (6)	N4—C8	1.389 (3)
Pt1—Cl2ⁱ	2.3161 (6)	C1—C2	1.358 (4)
Pt1—Cl2	2.3161 (6)	C1—C6	1.433 (3)
Pt1—Cl3	2.3222 (6)	C3—H3	0.89 (3)
Pt1—Cl3ⁱ	2.3222 (6)	C4—H4A	0.9600
O1—C8	1.213 (3)	C4—H4B	0.9600
O2—C6	1.213 (3)	C4—H4C	0.9600
N1—H1	0.846 (18)	C4—H4D	0.9600
N1—C2	1.370 (3)	C4—H4E	0.9600
N1—C3	1.335 (4)	C4—H4F	0.9600
N2—C1	1.380 (3)	C5—H5A	0.9600
N2—C3	1.312 (4)	C5—H5B	0.9600
N2—C4	1.469 (4)	C5—H5C	0.9600
N3—C2	1.354 (3)	C7—H7A	0.9600
N3—C5	1.468 (3)	C7—H7B	0.9600
N3—C8	1.389 (3)	C7—H7C	0.9600
N4—C6	1.399 (3)

Cl1ⁱ—Pt1—Cl1	180.0	C1—C2—N1	107.3 (2)
Cl1—Pt1—Cl2	89.97 (2)	N1—C3—H3	125 (2)
Cl1—Pt1—Cl2ⁱ	90.03 (2)	N2—C3—N1	109.9 (2)
Cl1ⁱ—Pt1—Cl2	90.03 (2)	N2—C3—H3	125 (2)
Cl1ⁱ—Pt1—Cl2ⁱ	89.97 (2)	N2—C4—H4A	109.5
Cl1—Pt1—Cl3ⁱ	89.93 (2)	N2—C4—H4B	109.5
Cl1—Pt1—Cl3	90.07 (2)	N2—C4—H4C	109.5
Cl1ⁱ—Pt1—Cl3	89.93 (2)	H4A—C4—H4B	109.5
Cl1ⁱ—Pt1—Cl3ⁱ	90.07 (2)	H4A—C4—H4C	109.5
Cl2—Pt1—Cl2ⁱ	180.0	H4B—C4—H4C	109.5
Cl2ⁱ—Pt1—Cl3	90.52 (3)	H4D—C4—H4E	109.5
Cl2—Pt1—Cl3	89.48 (3)	H4D—C4—H4F	109.5
Cl2ⁱ—Pt1—Cl3ⁱ	89.48 (3)	H4E—C4—H4F	109.5
Cl2—Pt1—Cl3ⁱ	90.52 (3)	N3—C5—H5A	109.5
Cl3ⁱ—Pt1—Cl3	180.0	N3—C5—H5B	109.5
C2—N1—H1	128 (2)	N3—C5—H5C	109.5
C3—N1—H1	124 (2)	H5A—C5—H5B	109.5
C3—N1—C2	107.7 (2)	H5A—C5—H5C	109.5
C1—N2—C4	125.7 (2)	H5B—C5—H5C	109.5
C3—N2—C1	108.2 (2)	O2—C6—N4	122.2 (2)
C3—N2—C4	126.1 (2)	O2—C6—C1	126.5 (3)
C2—N3—C5	123.2 (2)	N4—C6—C1	111.2 (2)
C2—N3—C8	117.9 (2)	N4—C7—H7A	109.5
C8—N3—C5	118.8 (2)	N4—C7—H7B	109.5
C6—N4—C7	116.2 (2)	N4—C7—H7C	109.5
C8—N4—C6	127.2 (2)	H7A—C7—H7B	109.5
C8—N4—C7	116.5 (2)	H7A—C7—H7C	109.5
N2—C1—C6	131.1 (2)	H7B—C7—H7C	109.5
C2—C1—N2	106.9 (2)	O1—C8—N3	120.5 (3)
C2—C1—C6	122.0 (2)	O1—C8—N4	122.1 (2)
N3—C2—N1	128.6 (2)	N4—C8—N3	117.3 (2)
N3—C2—C1	124.1 (2)

N2—C1—C2—N1	−0.4 (3)	C5—N3—C2—N1	−0.8 (4)
N2—C1—C2—N3	179.0 (2)	C5—N3—C2—C1	179.9 (3)
N2—C1—C6—O2	−0.4 (5)	C5—N3—C8—O1	−1.5 (4)
N2—C1—C6—N4	−179.0 (2)	C5—N3—C8—N4	177.2 (2)
C1—N2—C3—N1	0.3 (3)	C6—N4—C8—O1	−175.8 (3)
C2—N1—C3—N2	−0.6 (3)	C6—N4—C8—N3	5.4 (4)
C2—N3—C8—O1	175.7 (2)	C6—C1—C2—N1	−178.6 (2)
C2—N3—C8—N4	−5.5 (3)	C6—C1—C2—N3	0.7 (4)
C2—C1—C6—O2	177.4 (3)	C7—N4—C6—O2	3.3 (4)
C2—C1—C6—N4	−1.2 (3)	C7—N4—C6—C1	−178.1 (2)
C3—N1—C2—N3	−178.7 (3)	C7—N4—C8—O1	0.3 (4)
C3—N1—C2—C1	0.6 (3)	C7—N4—C8—N3	−178.4 (2)
C3—N2—C1—C2	0.0 (3)	C8—N3—C2—N1	−178.0 (3)
C3—N2—C1—C6	178.1 (3)	C8—N3—C2—C1	2.8 (4)
C4—N2—C1—C2	−179.4 (3)	C8—N4—C6—O2	179.4 (3)
C4—N2—C1—C6	−1.4 (4)	C8—N4—C6—C1	−2.0 (4)
C4—N2—C3—N1	179.8 (3)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Cl3ⁱⁱ	0.85 (2)	2.45 (2)	3.296 (2)	174 (3)
C3—H3···Cl2ⁱⁱ	0.89 (3)	2.81 (3)	3.455 (3)	131 (3)
C5—H5C···Cl2	0.96	2.91	3.563 (3)	127
C7—H7B···O1ⁱⁱⁱ	0.96	2.44	3.346 (4)	157

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

Acknowledgements

The X-ray diffraction experiment was carried out at the Centre of Shared Use of Physical Methods of Investigation of IPCE RAS.

Funding information

Funding for this research was provided by: Ministry of Science and Higher Education of the Russian Federation (award No. 122011300061-3). This work was supported by the RUDN University Strategic Academic Leadership Program.

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