Crystal structures and Hirshfeld surface analyses of hypoxanthine salts involving 5-sulfosalicylate and perchlorate anions

Sathya, U.; Nirmalram, J.S.; Gomathi, S.; Perdih, F.; Jegan Jennifer, S.; Abdul Razak, I.

doi:10.1107/S2056989022004753

research communications

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ISSN: 2056-9890

Volume 78| Part 6| June 2022| Pages 574-583

https://doi.org/10.1107/S2056989022004753

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Crystal structures and Hirshfeld surface analyses of hypoxanthine salts involving 5-sulfosalicylate and perchlorate anions

Udhayasuriyan Sathya,^a Jeyaraman Selvaraj Nirmalram,^a ^* Sundaramoorthy Gomathi,^b Franc Perdih,^c Samson Jegan Jennifer ^d and Ibrahim Abdul Razak ^d

^aCentre for Research and Development, PRIST Deemed to be University, Thanjavur 613 403, Tamil Nadu, India, ^bDepartment of Chemistry, Periyar Maniammai Institute of Science and Technology, Thanjavur 613 403, Tamil Nadu, India, ^cFaculty of Chemistry and Chemical Technology, University of Ljubljana, Vecna, pot 113, PO Box 537, SI-1000 Ljubljana, Slovenia, and ^dX-ray Crystallography Unit, School of Physics, University Sains Malaysia, 11800, USM, Penang, Malaysia
^*Correspondence e-mail: nirmalramjs@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 25 March 2022; accepted 3 May 2022; online 13 May 2022)

Two salts of 1,9-dihydropurin-6-one (hypoxanthine), namely, 6-oxo-1,9-dihydropurin-7-ium 5-sulfosalicylate dihydrate, C₅H₅N₄O⁺·C₇H₅O₆S⁻·2H₂O, (I), and 6-oxo-1,9-dihydropurin-7-ium perchlorate monohydrate, C₅H₅N₄O⁺·ClO₄⁻·H₂O, (II), have been synthesized and characterized using single-crystal X-ray diffraction and Hirshfeld analysis. In both salts, the hypoxanthine molecule is protonated at the N7 position of the purine ring. In salt (I), the cation and anion are connected through N—H⋯O interactions. The protonated hypoxanthine cations of salt (I) form base pairs with another symmetry-related hypoxanthine cation through N—H⋯O hydrogen bonds with an R₂²(8) ring motif, while in salt (II), the hypoxanthine cations are paired through a water molecule via N—H⋯O and O—H⋯N hydrogen bonds with an R₃³(11) ring motif. The packings within the crystal structures are stabilized by π–π stacking interactions in salt (I) and C—O⋯π interactions in salt (II). The combination of several interactions leads to the formation of supramolecular sheets extending parallel to (010) in salts (I) and (II). Hirshfeld surface analysis and fingerprint plots reveal that O⋯H/H⋯O contacts play the major role in the crystal packing of each of the salts, with a 54.1% contribution in salt (I) and 62.3% in salt (II).

Keywords: crystal structure; hydrogen bonding; Hirshfeld surface analysis; hypoxanthine.

CCDC references: 2170315; 2170314

1. Chemical context

1,9-Dihydropurin-6-one (hypoxanthine, C₅H₄N₄O), a notable purine-based nucleotide (Emel'yanenko et al., 2017 ), is present in the anticodon as nucleoside inosine in t-RNA (Costas & Acevedo-Chávez, 1997 ; Holley et al., 1965 ; Stryer, 1988 ; Plekan et al., 2012 ; Hughes, 1981 ; Schmalle et al., 1988 ). Hypoxanthine and xanthine are significant as drugs in the treatment of infections like gout and xanthinuria. Hypoxanthine is additionally utilized against hypoxia and is known to repress the impact of few medications (Dubler et al., 1987a ,b ; Biradha et al., 2010 ).

Hypoxanthine (HX), a potential oxygen-free radical generator, is a strong agent against cancer cells (Susithra et al., 2018 ; Latosińska et al., 2014 ; Rutledge et al., 2007 ). The presence of the imine group in its structure is responsible for its pharmacological activity. Hypoxanthine can exist in two stable tautomers, viz. as the oxo-N7(H) form and as the oxo-N9(H) form. When hypoxanthine interacts with strong acids, it becomes protonated at position N7 or N9. A limited number of hypoxanthine salts like hypoxanthine nitrate (Cabaj & Dominiak, 2021 ; Cabaj et al., 2019 ) and hypoxanthine hydrochloride monohydrate (Sletten & Jensen, 1969 ) have been reported so far in the literature.

The current article reports the crystal structures of hypoxanthinium 5-sulfosalicylate dihydrate, (I), and hypoxanthinium perchlorate monohydrate, (II), salts and the noncovalent interactions that govern their crystal packings.

2. Structural commentary

Salt (I) crystallizes with two hypoxanthinium cations (A⁺ and B⁺), two 5-sufosalicylate anions (5SCA⁻; A and B) and four solvent water molecules (O1W, O2W, O3W and O4W) in the asymmetric unit, as shown in Fig. 1. In salt (I), the B cation is equally disordered over two sets of sites for atoms C5B/C5C, C6B/C6C and O6B/O6C. Atoms H1B/H1C and H7B/H7C attached to N1B and N7B, respectively, are also disordered. The solvent water molecule O3W is also disordered over two positions. Atoms N7A and N7B are protonated, which is confirmed by widening of the C5A—N7A—C8A angle to 107.1 (4)° compared to the value of 103.8° in the two polymorphic forms of the neutral HX molecule (Schmalle et al., 1988; Yang & Xie, 2007 ); the situation for C5B—N7B—C8B is less clear due to the observed disorder. The torsion angles of N3A—C4A—C5A—N7A = −179.2 (4)° and N3B—C4B—C5C—N7B = −178.3 (6)° are similar to those of the two forms of the neutral HX molecule (−179.55 and −178.99°; Schmalle et al., 1988; Yang & Xie, 2007). The carboxylic acid group in each of the two 5SCA⁻ anions is coplanar with the benzene ring [O7A—C9A—C10A—C11A = −178.2 (4)° and O7B—C9B—C10B—C11B = 175.9 (4)°], a situation that is likewise observed for previously reported crystal structures involving 5SCA⁻ anions.

Figure 1
The asymmetric unit of salt (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonding and the disorder of cation B⁺ is shown.

Salt (II) crystallizes with one hypoxanthinium cation, one perchlorate anion (PCA⁻) and one solvent water molecule in the asymmetric unit. The molecular structure of salt (II) is shown in Fig. 2. Again, the N7 atom of the purine ring is protonated, as confirmed by the widening of the C5—N7—C8 angle to 108.00 (12)°. The N3—C4—C5—N7 torsion angle of 179.34 (14)° is similar to the values determined for salt (I). The PCA⁻ anion has the characteristic tetrahedral shape, with Cl—O bond lengths between 1.4116 (15) and 1.4421 (15) Å, and O—Cl—O angles between 108.29 (9) and 111.24 (12)°.

Figure 2
The asymmetric unit of salt (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonding.

3. Supramolecular features

In the crystal structure of salt (I), (010) sheets of cations and sheets of anions are stacked alternately along [010]. The crystal packing is governed by N—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds (Table 1). Symmetry-related A⁺ cations interact through a pair of N1A—H1A⋯O6A hydrogen bonds with a robust R₂²(8) motif (Bernstein et al., 1995 ; Motherwell et al., 2000 ). Solvent water molecule OW1 connects the A⁺ cation via N7A—H7A⋯O1W and O1W—H1WA⋯O6A hydrogen bonds with an R₄⁴(14) motif. The A⁺ cations are further connected via C2A—H2A⋯O1W, C8A—H8A⋯O2W, N9A—H9A⋯O2W and O2W—H2WA⋯N3A, N1A—H1A⋯O6A hydrogen bonds with R₃²(7), R₄⁴(14), R₄³(10) and R₄²(10) motifs (Fig. 3).

Table 1
Hydrogen-bond geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N7B—H7B⋯O3WAⁱ	0.86	2.26	3.08	158
O7A—H7D⋯O10Aⁱⁱ	0.82	1.86	2.677	170
O7B—H7E⋯O10Bⁱ	0.82	1.84	2.655	175
O9A—H9D⋯O12Bⁱⁱ	0.82	2.34	2.924	128
O9B—H9E⋯O12Aⁱⁱⁱ	0.82	2.54	3.143	131
O1W—H1WA⋯O6A^iv	0.85	2.31	2.801	117
O1W—H1WA⋯O10B^iv	0.85	2.28	2.917	132
N9B—H9B⋯O6B^v	0.86	2.42	3.044	130
N9B—H9B⋯O3WA^vi	0.86	2.47	3.07	128
N1A—H1A⋯O6A^vii	0.86	2.05	2.898	170
N1B—H1C⋯O4W	0.86	2.22	2.890	135
N1B—H1C⋯O11A	0.86	2.45	2.998	122
O1W—H1WB⋯O12B	0.85	2.01	2.844	169
O2W—H2WA⋯N3A	0.83	2.07	2.849	157
O2W—H2WB⋯O12A	0.82	2.03	2.815	160
N7A—H7A⋯O1W	0.86	1.77	2.615	168
N9A—H9A⋯O2W	0.86	1.89	2.697	157
C2A—H2A⋯O1Wⁱⁱ	0.93	2.43	3.149	134
C2B—H2B⋯O11A	0.93	2.46	2.974	114
C8A—H8A⋯O2W^viii	0.93	2.40	3.310	167
C15B—H15B⋯O9A	0.93	2.59	3.510	172
Symmetry codes: (i) x+1, y, z; (ii) ; (iii) ; (iv) ; (v) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (vi) $[x+1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (vii) ; (viii) .

Figure 3
The crystal packing of (I), showing the N—H⋯O and O—H⋯O ring motifs formed between the A⁺ cation and water molecules.

The B⁺ cations interact with the O atom of the solvent water molecules O3W and O4W through N1B—H1C⋯O4W and N9B—H9B⋯O3WA, and with N9B—H9B⋯O6B with an R₂²(7) motif. Short O3WA⋯O4W contacts with an R₅⁵(20) motif are also observed (Fig. 4). Furthermore, the two 5SCA⁻ anions (A and B) self assemble into sheets by interaction of symmetry-related counterparts through O7A—H7D⋯O10A and O7B—H7E⋯O10B, respectively (Fig. 5). A and B sheets are interconnected through O9B—H9E⋯O12A and through O9A—H9D⋯O12B and C15B—H15B⋯O9A interactions, resulting in R₂²(7), R₄⁴(23) and R₄⁴(26) ring motifs. Moreover, cation B⁺ interacts with 5SCA⁻ (A) via N1B—H1C⋯O11A and C2B—H2B⋯O11A with an R₂¹(5) motif. Another interconnection between cationic and anionic sheets involves the solvent water molecules through O1W—H1WA⋯O10B, O1W—H1WB⋯O12B, O2W—H2WA⋯N3A and O2W—H2WB⋯O12A (Fig. 6).

Figure 4
The crystal packing of (I), showing the N—H⋯O and O—H⋯O ring motifs formed between the B⁺ cation and (disordered) water molecules.

Figure 5
The supramolecular layer of assembled 5SCA⁻ anions in salt (I).

Figure 6
The alternating arrangement of cationic and anionic sheets in salt (I).

The crystal structure of (I) is consolidated by π–π interactions between the phenyl rings of the two 5SCA anions (C10A–C15A and C10B–C15B), and the imidazole ring (C4A–N9A) and the pyrimidine ring (N1A–C6A) of cation A⁺, with centroid-to-centroid distances of 3.547 (3), 3.562 (3), 3.554 (3) and 3.533 (3) Å, and slippages of 0.815, 1.300, 1.182 and 1.105 Å (Fig. 7).

Figure 7
π–π stacking interactions in (I) between the imidazole and pyrimidine rings of the cations and the phenyl rings of the anions.

In the crystal structure of salt (II), (010) sheets of cations and sheets of anions are stacked alternately along [010]. The crystal packing of salt (II) is dominated by N—H⋯O and O—H⋯O hydrogen bonds, and to a minor extent by C—H⋯O hydrogen bonds (Table 2). The protonated N atom of the cation forms an N7—H7⋯O1Wⁱⁱ hydrogen bond with the O atom of the water molecule. The water molecule disrupts the formation of base pairs but connects symmetry-related cations through O1W—H2W⋯N3^iv. Additional N9—H9⋯O6ⁱⁱⁱ interactions with an R₃³(11) ring motif generate a cationic strand along [201]. Parallel cationic strands are connected through the solvent water molecule and the PCA⁻ anion through O1W—H1W⋯O3 and bifurcated N1—H1⋯O4 and N1—H1⋯O5 interactions, respectively, forming R₃²(9), R₆⁴(14) and R₆⁶(20) motifs. The crystal packing of salt (II) is shown in Fig. 8. The crystal structure is further stabilized by carbonyl⋯π (π refers to the ring system of the cation) interactions, with distances of 3.6097 (13), 3.2983 (13), 3.4580 (13) and 3.7236 (14) Å (Fig. 9).

Table 2
Hydrogen-bond geometry (Å, °) for (II)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4	0.82	2.60	3.249	138
N1—H1⋯O5	0.82	2.09	2.879	162
N7—H7⋯O2ⁱ	0.91	2.60	3.031	110.2
N7—H7⋯O1Wⁱⁱ	0.91	1.76	2.6489	165
N9—H9⋯O6ⁱⁱⁱ	0.84	1.93	2.7602	166
O1W—H1W⋯O3^iv	0.85	2.17	3.018	172
O1W—H2W⋯N3	0.85	2.11	2.951	172
C8—H8⋯O2ⁱ	0.93	2.47	2.970	114
C8—H8⋯O3ⁱⁱⁱ	0.93	2.47	3.268	144
C8—H8⋯O4ⁱⁱⁱ	0.93	2.55	3.072	116
Symmetry codes: (i) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[x+1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[x-1, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) .

Figure 8
A view of the supramolecular arrangement involving hydrogen-bonded rings in salt (II).

Figure 9
A view of the PCA⁻ anions and water molecules connecting sheets through O—H⋯O hydrogen bonds and a view of the C—O⋯π interactions (π = imidazole and pyrimidine rings of the cation) in salt (II). [Symmetry codes: (i) −x + 2, y − $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (ii) x + 1, −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ .]

4. Hirshfeld surface analysis

Hirshfeld surface (HS) analyses of salts (I) and (II) were performed using CrystalExplorer17 (Turner et al., 2017 ). The results of the HS analysis mapped over d_norm are shown in Figs. 10(a) and 10(b) for (I) and (II), respectively. Corresponding two-dimensional fingerprint plots (Spackman & Jayatilaka, 2009 ) for (I) and (II) are shown in Figs. 11 and 12, respectively. The contributions of the noncovalent interactions to the HS in the two salts are: O⋯H/H⋯O 54.1% (I), 62.3% (II); N⋯H/H⋯N 3.1% (I), 6.8% (II); C⋯H/H⋯C 5.9% (I), 5.4% (II); H⋯H/H⋯H 16.0% (I), 5.3% (II); C⋯C/C⋯C 0.9% (I), 0.1% (II).

Figure 10
Hirshfeld surface for salts (a) (I) and (b) (II) mapped over d_norm.

Figure 11
Fingerprint plots of salt (I) showing all intermolecular interactions and delineated into O⋯H/H⋯O, H⋯N/N⋯H, C⋯O, C⋯N, C⋯H/H⋯C and H⋯H contacts.

Figure 12
Fingerprint plots of salt (II) showing all intermolecular interactions and delineated into O⋯H/H⋯O, H⋯N/N⋯H, C⋯O, C⋯H/H⋯C and H⋯H contacts.

5. Comparison with the structures of related compounds

Crystal data, supramolecular interactions and hydrogen bonding motifs of structurally similar halide/nitrate/phosphite/phosphate/perchlorate or sulfate salts like guanidinium bromide (Wei, 1977 ), guanidinium chloride (Maixner & Zachová, 1991 ), bis(guanidinium) hydrogen phosphate 2.5-hydrate (Low et al., 1986 ), guanidinium phosphite (Bendeif et al., 2007 ), guanidinium sulfate (Cherouana et al., 2003 ), guanidinium dinitrate dihydrate (Bouchouit et al., 2002 ), xanthinium nitrate, xanthinium sulfate (Sridhar, 2011 ), xanthinium perchlorate dihydrate (Biradha et al., 2010), hypoxanthinium chloride monohydrate (Sletten & Jensen, 1969) and hypoxanthinium nitrate monohydrate (Cabaj et al., 2019) are listed and compared in Table 3.

Table 3
Comparison of salt forms of purine derivatives containing halides/nitrate/phosphite/phosphate/sulfate and perchlorates as anions

Compound	Space group	Primary interaction between	Graph-set motif	Motif type	Secondary interaction between	Graph-set motif	Motif type
Guanidinium hydrochloride	Monoclinic P2₁/c,	N—H⋯N,	R₂²(8),	IV and V	N—H⋯Cl,	R₃²(8),	XII and XIII
	a = 4.479 Å	N—H⋯O	R₂²(10)		C—H⋯Cl,	R₄³(11)
	b = 9.995 Å				O—H⋯N,
	c = 19.304 Å				O—H⋯Cl
	β = 107.90°
Guanidinium hydrobromide	Monoclinic P2₁/c	N—H⋯N,	R₂²(8),	IV and V	N—H⋯Br,	R₃²(8),	XII and XIII
	a = 4.8708 Å	N—H⋯O	R₂²(10)		N—H⋯N,	R₄³(11)
	b = 13.237 Å				O—H⋯Br,
	c = 14.638 Å				C—H⋯Br
	β = 93.906°
Guanidinium dinitrate dihydrate	Monoclinic P2₁/c	N—H⋯O	R₂²(8)	V	N—H⋯O,	R₄³(12)	XII
	a = 6.6340 Å				O—H⋯O
	b = 10.2020 Å
	c = 11.0440 Å
	β = 106.04°
Guanidinium phosphite monohydrate	Monoclinic P2₁/c	N—H⋯N	R₂²(8)	IV	N—H⋯O	R₂¹(6),	XII and XVIII
	a = 4.9700 Å					R₄³(10)
	b = 12.7506 Å
	c = 15.0499 Å
	β = 92.293°
Guanidinium phosphite dihydrate form (I)	Monoclinic P2₁/c	N—H⋯N	R₂²(8)	IV	N—H⋯N,	R₃²(8),	XIII and XVIII
	a = 4.6812 Å				N—H⋯O	R₂¹(6)
	b = 24.0561 Å
	c = 9.5186 Å
	β = 99.773°
Guanidinium phosphite dihydrate form (II)	Monoclinic P2₁/c	N—H⋯N	R₂²(8)	IV	N—H⋯N,	R₃²(8),	XIII and XVIII
	a = 4.7340 Å				N—H⋯O	R₂¹(6)
	b = 24.0450 Å
	c = 9.5050 Å
	β = 98.860°
Guanidinium phosphate hydrate form (I)	Triclinic, P $[\overline{1}]$	N—H⋯N	R₂²(8)	IV	N—H⋯O,	R₂²(9)	XVI and XVII
	a = 9.607 Å				O—H⋯O	R₂²(10)
	b = 10.221 Å
	c = 10.603 Å
	α = 84.5°
	β = 108.2°
	γ = 119.7°
Guanidinium phosphate monohydrate form (II)	Monoclinic P2₁/n	N—H⋯N	R₂²(8)	IV	N—H⋯O,	R₂²(8),	VI, XIII and XVI
	a = 4.5414 Å				O—H⋯O	R₃²(8),
	b = 12.5774 Å					R₂²(9)
	c = 18.1485 Å
	β = 93.689 °
Guanidinium sulfate monohydrate	Monoclinic P2₁/c	N—H⋯O	R₂²(8)	VI	N—H⋯O,	R₄³(12)	XV
	a = 8.9940 Å				O—H⋯O
	b = 10.2020 Å
	c = 11.0440 Å
	β = 106.04°
Xanthinium nitrate monohydrate	Triclinic, P $[\overline{1}]$	N—H⋯O	R₂²(8)	I	O—H⋯N,	R₂²(4),	VIII, XI and XIII
	a = 5.0416 Å				O—H⋯O	R₃²(8),
	b = 7.4621 Å					R₆⁴(14)
	c = 12.1396 Å
	α = 80.248°
	β = 80.800°
	γ = 75.657°
Xanthinium sulfate monohydrate	Monoclinic P2₁	N—H⋯O	R₂²(8)	I	O—H⋯N,	R₃²(8)	XIII
	a = 5.183 Å
	b = 24.805 Å
	c = 7.701 Å
	β = 103.510°
Xanthinium perchlorate dihydrate	Triclinic, P $[\overline{1}]$	N—H⋯O	R₂²(8)	I	O—H⋯N,	R₃²(8)	XIII
	a = 5.1625 Å				O—H⋯O
	b = 7.7449 Å
	c = 13.696 Å
	α = 100.214°
	β = 91.591°
	γ = 100.880°
Hypoxanthinium hydrochloride monohydrate	Monoclinic P2₁/c	N—H⋯Cl	R₃²(9)	III	N—H⋯Cl,	R₃³(11),	IX, X and XI
	a = 4.8295 Å				C—H⋯Cl,	R₄⁴(16),
	b = 17.7285 Å				O—H⋯N,	R₆⁴(14)
	c = 9.0077 Å				O—H⋯Cl
	β = 94.59°
Hypoxanthinium nitrate monohydrate form (I)	Orthorhombic Pnma	N—H⋯O	R₂²(8)	II	N—H⋯O,	R₂²(6),	XIII and XIV
	a = 13.701 Å				O—H⋯O,	R₃²(8),
	b = 6.236 Å					R₆⁶(20)
	c = 10.078 Å
Hypoxanthinium nitrate monohydrate form (II)	Monoclinic P2₁/n	N—H⋯O	R₂²(8)	II	N—H⋯O,	R₂²(6),	XIII and XIV
	a = 6.1452 Å				O—H⋯O,	R₃²(8)
	b = 13.7517 Å
	c = 10.0414 Å
	β = 95.601°

A comparison of salts (I) and (II) with the related salt forms of guanine, xanthinium and hypoxanthine reveal that, in most of the crystal structures containing purine derivatives, the purine forms base pairs through pairs of N—H⋯O or N—H⋯N hydrogen bonds with an R₂²(8) primary ring motif. When it comes to an interaction between the purine base and a strong acid, the chloride/nitrate/sulfate/phosphite/phosphate or perchlorate salts of guanine/xanthine and hypoxanthine have different molecular recognition patterns. The most important primary and secondary motifs formed by hypoxanthine and similar compounds are summarized in Figs. 13 and 14. Crystallographic studies of salts involving perchlorate and sulfate anions reveal that most of these salts have similar crystal packing arrangements (Bishop et al., 2014 ). In general, salts of structurally similar systems will have similar molecular recognition patterns and supramolecular motifs. However, for salts (I) and (II) and related systems compiled in Table 3, great similarities are not observed. The differences in molecular recognition and supramolecular self-assembly might be due to the involvement of other functional groups or substituents in the structures, the intrusion of water molecules in the crystal structure, or the ratio of anions and cations present in the asymmetric unit.

Figure 13
Primary ring motifs observed in purine derivatives.

Figure 14
Secondary ring motifs observed in purine derivatives.

6. Synthesis and crystallization

Salt (I) was synthesized by mixing an equimolar ratio of hypoxanthine (0.0340 g) and 5-sulfosalicylic acid (0.0545 g) in hot water. The solution was heated to 333 K for 1 h and then allowed to cool slowly to room temperature. Colourless needle-shaped crystals were harvested from the mother liquid after one week.

Salt (II) was synthesized by mixing an equimolar ratio of hypoxanthine (0.0340 g) and iron perchlorate monohydrate (0.0681 g) in hot water. The solution was heated to 333 K with constant stirring for 1 h and then allowed to cool slowly to room temperature. Colourless plate-like crystals were harvested from the mother liquid after one week.

7. Refinement

Crystal data, data collection and structure refinement details of salts (I) and (II) are summarized in Table 4. In salt (I), carbon (C5 and C6) and oxygen (O6) atoms of cation B are equally disordered over two sets of sites, with a refined occupancy ratio of 0.503 (18):0.497 (18). The solvent water molecule O3W is disordered over two positions, with a refined site-occupancy ratio of 0.58 (6):0.42 (6). The H atoms of water molecules O1W and O2W were located from a difference Fourier map, and the O—H distance restrained to 0.82 Å. Attempts to localize the H atoms of O3W and O4W in (I) from difference Fourier maps failed as there were no relevant electron densities close to these atoms. Hence, these H atoms are not part of the model but are included in the formula. All C- and N-bound H atoms in (I) were placed in idealized positions and refined freely using a riding model, with C—H = 0.95 Å and N—H = 0.86 Å, and with U_iso(H) = 1.2U_eq(C,N). In salt (II), the N-bound H atoms were located in a difference Fourier map and refined freely. The H atoms of the water molecule were likewise located from a difference Fourier map. The geometry of the water molecule was restrained using DFIX commands with an O—H distance of 0.85 Å and an H⋯H distance of 1.36 Å. All C-bound H atoms were treated as for salt (I).

Table 4
Experimental details

	(I)	(II)
Crystal data
Chemical formula	C₅H₅N₄O⁺·C₇H₅O₆S⁻·2H₂O	C₅H₅N₄O⁺·ClO₄⁻·H₂O
M_r	388.32	254.60
Crystal system, space group	Monoclinic, P2₁/c	Monoclinic, P2₁/c
Temperature (K)	293	296
a, b, c (Å)	8.7055 (3), 25.9927 (13), 13.6479 (5)	5.0307 (6), 20.386 (2), 9.0181 (10)
β (°)	91.864 (3)	94.233 (2)
V (Å³)	3086.6 (2)	922.33 (18)
Z	8	4
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	0.27	0.44
Crystal size (mm)	0.55 × 0.20 × 0.10	0.45 × 0.02 × 0.003

Data collection
Diffractometer	Bruker APEXII CCD	Bruker APEXII CCD
Absorption correction	–	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	–	0.957, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	21075, 7079, 5905	16360, 2752, 2370
R_int	0.032	0.025
(sin θ/λ)_max (Å⁻¹)	0.649	0.711

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.087, 0.190, 1.22	0.038, 0.111, 1.05
No. of reflections	7079	2752
No. of parameters	521	165
No. of restraints	2	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.74, −0.43	0.37, −0.29
Computer programs: APEX2 and SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), Mercury (Macrae et al., 2020 ), POVRay (Cason, 2004 ), PLATON (Spek, 2020 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 2170315; 2170314

Crystal structure: contains datablocks I, II, global. DOI: https://doi.org/10.1107/S2056989022004753/wm5640sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022004753/wm5640Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989022004753/wm5640IIsup3.hkl

checkCIF report

Computing details top

For both structures, data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: PLATON (Spek, 2020), Mercury (Macrae et al., 2020) and POVRay (Cason, 2004); software used to prepare material for publication: PLATON (Spek, 2020) and publCIF (Westrip, 2010).

6-Oxo-1,9-dihydropurin-7-ium 5-sulfosalicylate dihydrate (I) top

Crystal data top

C₅H₅N₄O⁺·C₇H₅O₆S⁻·2H₂O	F(000) = 1600
M_r = 388.32	D_x = 1.671 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.7055 (3) Å	Cell parameters from 7079 reflections
b = 25.9927 (13) Å	θ = 2.8–27.5°
c = 13.6479 (5) Å	µ = 0.27 mm⁻¹
β = 91.864 (3)°	T = 293 K
V = 3086.6 (2) Å³	Needle, colourless
Z = 8	0.55 × 0.20 × 0.10 mm

Data collection top

Bruker APEXII CCD diffractometer	R_int = 0.032
φ and ω scans	θ_max = 27.5°, θ_min = 2.9°
21075 measured reflections	h = −11→11
7079 independent reflections	k = −23→33
5905 reflections with I > 2σ(I)	l = −17→17

Refinement top

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)] = 0.087	w = 1/[σ²(F_o²) + (0.0167P)² + 13.1153P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.190	(Δ/σ)_max < 0.001
S = 1.22	Δρ_max = 0.74 e Å⁻³
7079 reflections	Δρ_min = −0.43 e Å⁻³
521 parameters	Extinction correction: SHELXL (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.0013 (3)

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)
O6A	0.1947 (4)	0.49617 (15)	0.5394 (2)	0.0415 (8)
N1A	−0.0096 (4)	0.49891 (15)	0.6407 (3)	0.0312 (8)
H1A	−0.072122	0.497638	0.590694	0.037*
N3A	0.0062 (4)	0.50335 (15)	0.8125 (3)	0.0311 (8)
N7A	0.3886 (4)	0.49922 (15)	0.7338 (3)	0.0321 (8)
H7A	0.459823	0.497846	0.691626	0.038*
N9A	0.2725 (4)	0.50320 (16)	0.8730 (3)	0.0331 (9)
H9A	0.257740	0.504829	0.934876	0.040*
C2A	−0.0710 (5)	0.50158 (18)	0.7299 (3)	0.0325 (10)
H2A	−0.177576	0.502197	0.732324	0.039*
C4A	0.1607 (5)	0.50245 (17)	0.8000 (3)	0.0263 (9)
C5A	0.2318 (4)	0.50003 (17)	0.7134 (3)	0.0261 (9)
C6A	0.1473 (5)	0.49805 (18)	0.6231 (3)	0.0287 (9)
C8A	0.4084 (5)	0.50097 (19)	0.8307 (3)	0.0355 (10)
H8A	0.503178	0.500683	0.864222	0.043*
N1B	0.7702 (5)	0.25698 (19)	0.9705 (5)	0.0620 (15)
H1C	0.689866	0.258941	1.005445	0.074*	0.497 (18)
H1B	0.716586	0.258513	1.022312	0.074*	0.503 (18)
C2B	0.7345 (7)	0.2589 (2)	0.8774 (6)	0.0581 (16)
H2B	0.631879	0.262454	0.857329	0.070*
N3B	0.8390 (5)	0.25613 (17)	0.8117 (3)	0.0445 (10)
C4B	0.9779 (5)	0.25070 (18)	0.8592 (3)	0.0331 (10)
O6B	0.9419 (18)	0.2493 (6)	1.1190 (8)	0.054 (3)	0.497 (18)
C5C	1.0267 (15)	0.2496 (4)	0.9577 (8)	0.035 (3)	0.497 (18)
C6B	0.9094 (14)	0.2524 (4)	1.0314 (7)	0.035 (3)	0.497 (18)
O6C	1.0195 (19)	0.2484 (6)	1.1206 (10)	0.062 (3)	0.503 (18)
C5B	0.9336 (17)	0.2513 (4)	0.9552 (8)	0.040 (3)	0.503 (18)
C6C	1.0442 (17)	0.2479 (4)	1.0326 (7)	0.048 (4)	0.503 (18)
N7B	1.1875 (6)	0.2444 (2)	0.9780 (5)	0.0680 (16)
H7B	1.241971	0.242864	1.031666	0.082*	0.497 (18)
H7C	1.267726	0.243141	1.016423	0.082*	0.503 (18)
C8B	1.2225 (7)	0.2428 (2)	0.8848 (6)	0.0565 (16)
H8B	1.324295	0.239139	0.867383	0.068*
N9B	1.1141 (5)	0.24629 (17)	0.8172 (4)	0.0479 (11)
H9B	1.127857	0.245844	0.755081	0.058*
O3WA	0.367 (4)	0.2714 (4)	1.1689 (17)	0.063 (5)	0.58 (6)
O3WB	0.296 (4)	0.2700 (6)	1.1468 (11)	0.043 (6)	0.42 (6)
S1A	0.40654 (12)	0.36757 (5)	0.96698 (8)	0.0300 (3)
O7A	−0.1915 (4)	0.38972 (17)	0.9153 (3)	0.0473 (10)
H7D	−0.284261	0.394380	0.919381	0.071*
O8A	−0.2547 (4)	0.38674 (17)	0.7567 (3)	0.0489 (10)
O9A	−0.0354 (4)	0.37374 (16)	0.6296 (2)	0.0453 (9)
H9D	−0.123261	0.380142	0.645875	0.068*
O10A	0.5153 (4)	0.40963 (14)	0.9514 (3)	0.0386 (8)
O11A	0.4769 (4)	0.31756 (14)	0.9629 (3)	0.0467 (9)
O12A	0.3208 (4)	0.37511 (15)	1.0554 (2)	0.0429 (9)
C9A	−0.1574 (5)	0.38438 (18)	0.8225 (3)	0.0309 (9)
C10A	0.0083 (5)	0.37720 (17)	0.8061 (3)	0.0295 (9)
C11A	0.0590 (5)	0.37254 (18)	0.7101 (3)	0.0322 (10)
C12A	0.2158 (5)	0.3673 (2)	0.6944 (4)	0.0381 (11)
H12A	0.250192	0.364424	0.630852	0.046*
C13A	0.3201 (5)	0.36641 (19)	0.7726 (3)	0.0352 (10)
H13A	0.424567	0.363245	0.761467	0.042*
C14A	0.2696 (5)	0.37022 (17)	0.8681 (3)	0.0299 (9)
C15A	0.1145 (5)	0.37553 (17)	0.8842 (3)	0.0287 (9)
H15A	0.080905	0.378003	0.948039	0.034*
S1B	0.56102 (12)	0.37011 (5)	0.45829 (9)	0.0341 (3)
O7B	1.1577 (4)	0.38612 (17)	0.4147 (2)	0.0443 (9)
H7E	1.248391	0.394576	0.418788	0.066*
O8B	1.2092 (4)	0.37883 (17)	0.2566 (3)	0.0497 (10)
O9B	0.9832 (4)	0.36982 (17)	0.1295 (2)	0.0492 (9)
H9E	1.073533	0.369136	0.148463	0.074*
O10B	0.4520 (4)	0.41174 (15)	0.4380 (3)	0.0465 (9)
O11B	0.4889 (4)	0.31994 (16)	0.4549 (3)	0.0542 (10)
O12B	0.6496 (4)	0.37900 (17)	0.5491 (3)	0.0509 (10)
C9B	1.1165 (5)	0.37948 (18)	0.3224 (3)	0.0317 (10)
C10B	0.9504 (5)	0.37406 (17)	0.3041 (3)	0.0280 (9)
C11B	0.8925 (5)	0.37007 (18)	0.2071 (3)	0.0333 (10)
C12B	0.7338 (6)	0.3667 (2)	0.1889 (4)	0.0405 (11)
H12B	0.695190	0.363737	0.124781	0.049*
C13B	0.6350 (5)	0.36764 (19)	0.2646 (4)	0.0365 (11)
H13B	0.529554	0.365968	0.251642	0.044*
C14B	0.6914 (5)	0.37113 (17)	0.3618 (3)	0.0287 (9)
C15B	0.8480 (5)	0.37456 (16)	0.3811 (3)	0.0269 (9)
H15B	0.885372	0.377214	0.445531	0.032*
O1W	0.6140 (4)	0.48175 (16)	0.6162 (2)	0.0449 (9)
H1WA	0.605842	0.503025	0.569001	0.067*
H1WB	0.613001	0.452409	0.588798	0.067*
O2W	0.2476 (4)	0.48039 (15)	1.0649 (3)	0.0412 (8)
O4W	0.6239 (8)	0.2277 (2)	1.1488 (4)	0.100 (2)
H2WA	0.161 (5)	0.487 (4)	1.082 (7)	0.150*
H2WB	0.270 (12)	0.4502 (13)	1.075 (8)	0.150*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O6A	0.0336 (17)	0.066 (2)	0.0244 (16)	−0.0003 (17)	0.0008 (13)	−0.0022 (16)
N1A	0.0239 (18)	0.041 (2)	0.0279 (19)	0.0016 (16)	−0.0058 (14)	−0.0027 (17)
N3A	0.0270 (18)	0.040 (2)	0.0268 (19)	0.0015 (16)	0.0048 (15)	0.0003 (16)
N7A	0.0220 (17)	0.045 (2)	0.0296 (19)	0.0007 (16)	0.0021 (14)	0.0066 (17)
N9A	0.0300 (19)	0.049 (2)	0.0205 (17)	0.0018 (17)	−0.0007 (14)	0.0037 (17)
C2A	0.026 (2)	0.036 (2)	0.036 (2)	0.0014 (18)	0.0062 (18)	−0.002 (2)
C4A	0.028 (2)	0.031 (2)	0.0198 (19)	0.0007 (17)	0.0007 (16)	0.0010 (17)
C5A	0.0191 (18)	0.036 (2)	0.023 (2)	0.0006 (17)	0.0023 (15)	0.0005 (18)
C6A	0.030 (2)	0.034 (2)	0.023 (2)	−0.0007 (18)	0.0008 (16)	0.0000 (18)
C8A	0.025 (2)	0.047 (3)	0.034 (2)	−0.003 (2)	0.0002 (18)	0.007 (2)
N1B	0.034 (2)	0.046 (3)	0.106 (5)	0.002 (2)	0.006 (3)	−0.012 (3)
C2B	0.046 (3)	0.044 (3)	0.086 (5)	0.003 (3)	0.017 (3)	−0.002 (3)
N3B	0.037 (2)	0.043 (2)	0.052 (3)	0.0017 (19)	−0.008 (2)	0.003 (2)
C4B	0.038 (2)	0.029 (2)	0.032 (2)	0.0005 (19)	0.0027 (19)	0.0034 (19)
O6B	0.058 (7)	0.077 (7)	0.026 (4)	−0.009 (7)	−0.003 (5)	−0.003 (4)
C5C	0.023 (6)	0.030 (5)	0.051 (7)	0.004 (4)	−0.005 (5)	−0.003 (4)
C6B	0.052 (8)	0.034 (5)	0.020 (5)	−0.003 (5)	−0.004 (4)	−0.001 (4)
O6C	0.061 (8)	0.081 (7)	0.044 (6)	−0.014 (8)	−0.012 (6)	0.009 (5)
C5B	0.040 (8)	0.031 (5)	0.048 (7)	−0.006 (5)	0.001 (5)	−0.001 (5)
C6C	0.094 (12)	0.032 (5)	0.018 (5)	−0.013 (6)	0.020 (5)	0.004 (4)
N7B	0.041 (3)	0.047 (3)	0.115 (5)	−0.003 (2)	−0.009 (3)	0.002 (3)
C8B	0.035 (3)	0.044 (3)	0.089 (5)	0.005 (2)	−0.015 (3)	−0.004 (3)
N9B	0.047 (3)	0.044 (3)	0.053 (3)	−0.004 (2)	0.011 (2)	−0.008 (2)
O3WA	0.054 (12)	0.070 (6)	0.065 (7)	−0.018 (5)	0.002 (9)	0.012 (5)
O3WB	0.039 (13)	0.056 (6)	0.032 (6)	0.001 (6)	−0.005 (5)	−0.005 (5)
S1A	0.0190 (5)	0.0406 (6)	0.0304 (5)	0.0041 (4)	0.0014 (4)	0.0024 (5)
O7A	0.0204 (15)	0.082 (3)	0.0395 (19)	0.0058 (18)	0.0025 (14)	0.0025 (19)
O8A	0.0254 (16)	0.081 (3)	0.040 (2)	0.0042 (17)	−0.0062 (14)	0.0015 (19)
O9A	0.0374 (19)	0.064 (2)	0.0339 (18)	0.0009 (19)	−0.0081 (15)	0.0020 (18)
O10A	0.0233 (15)	0.048 (2)	0.045 (2)	−0.0038 (14)	−0.0008 (14)	0.0051 (16)
O11A	0.0363 (19)	0.045 (2)	0.058 (2)	0.0119 (16)	−0.0007 (17)	0.0030 (18)
O12A	0.0297 (17)	0.066 (2)	0.0331 (18)	0.0037 (17)	0.0043 (14)	0.0005 (17)
C9A	0.024 (2)	0.036 (2)	0.033 (2)	−0.0022 (18)	−0.0001 (17)	0.0048 (19)
C10A	0.0214 (19)	0.029 (2)	0.038 (2)	0.0005 (17)	0.0022 (17)	0.0051 (19)
C11A	0.032 (2)	0.031 (2)	0.033 (2)	0.0002 (19)	−0.0038 (18)	0.0015 (19)
C12A	0.036 (2)	0.048 (3)	0.031 (2)	0.001 (2)	0.0036 (19)	−0.001 (2)
C13A	0.024 (2)	0.044 (3)	0.038 (2)	0.005 (2)	0.0063 (18)	−0.004 (2)
C14A	0.024 (2)	0.031 (2)	0.035 (2)	0.0021 (17)	−0.0004 (17)	−0.0004 (19)
C15A	0.024 (2)	0.032 (2)	0.031 (2)	0.0006 (17)	0.0008 (16)	−0.0007 (18)
S1B	0.0199 (5)	0.0449 (7)	0.0374 (6)	0.0012 (5)	−0.0017 (4)	0.0018 (5)
O7B	0.0216 (15)	0.080 (3)	0.0314 (17)	−0.0009 (17)	−0.0012 (13)	0.0034 (18)
O8B	0.0331 (18)	0.080 (3)	0.0366 (19)	−0.0020 (18)	0.0085 (15)	−0.0028 (19)
O9B	0.048 (2)	0.069 (3)	0.0303 (18)	0.000 (2)	0.0063 (15)	−0.0004 (18)
O10B	0.0261 (17)	0.053 (2)	0.060 (2)	0.0086 (16)	−0.0035 (16)	−0.0015 (19)
O11B	0.041 (2)	0.052 (2)	0.070 (3)	−0.0094 (18)	0.0085 (19)	0.003 (2)
O12B	0.0287 (17)	0.088 (3)	0.0354 (19)	0.0048 (19)	−0.0048 (14)	−0.003 (2)
C9B	0.029 (2)	0.036 (2)	0.030 (2)	0.0049 (19)	0.0029 (18)	0.0043 (19)
C10B	0.025 (2)	0.029 (2)	0.030 (2)	0.0021 (17)	−0.0024 (16)	0.0034 (18)
C11B	0.038 (2)	0.035 (2)	0.027 (2)	0.000 (2)	0.0025 (18)	0.0020 (19)
C12B	0.039 (3)	0.050 (3)	0.032 (2)	−0.002 (2)	−0.007 (2)	−0.006 (2)
C13B	0.027 (2)	0.041 (3)	0.041 (3)	−0.003 (2)	−0.0124 (19)	−0.002 (2)
C14B	0.025 (2)	0.031 (2)	0.030 (2)	−0.0007 (17)	−0.0004 (16)	0.0033 (19)
C15B	0.0243 (19)	0.029 (2)	0.027 (2)	0.0013 (17)	−0.0014 (16)	−0.0012 (18)
O1W	0.0373 (19)	0.064 (2)	0.0336 (18)	−0.0042 (19)	0.0112 (16)	0.0006 (17)
O2W	0.0378 (19)	0.057 (2)	0.0288 (17)	0.0041 (17)	0.0081 (14)	0.0002 (17)
O4W	0.165 (6)	0.065 (3)	0.067 (3)	0.006 (4)	−0.048 (4)	−0.014 (3)

Geometric parameters (Å, º) top

O6A—C6A	1.228 (5)	S1A—O12A	1.453 (3)
N1A—C2A	1.346 (6)	S1A—O10A	1.466 (3)
N1A—C6A	1.395 (5)	S1A—C14A	1.772 (4)
N1A—H1A	0.8600	O7A—C9A	1.318 (6)
N3A—C2A	1.293 (6)	O7A—H7D	0.8200
N3A—C4A	1.362 (5)	O8A—C9A	1.216 (5)
N7A—C8A	1.330 (6)	O9A—C11A	1.350 (5)
N7A—C5A	1.384 (5)	O9A—H9D	0.8200
N7A—H7A	0.8600	C9A—C10A	1.479 (6)
N9A—C8A	1.334 (6)	C10A—C15A	1.389 (6)
N9A—C4A	1.370 (5)	C10A—C11A	1.402 (6)
N9A—H9A	0.8600	C11A—C12A	1.395 (6)
C2A—H2A	0.9300	C12A—C13A	1.378 (7)
C4A—C5A	1.354 (6)	C12A—H12A	0.9300
C5A—C6A	1.415 (6)	C13A—C14A	1.394 (6)
C8A—H8A	0.9300	C13A—H13A	0.9300
N1B—C2B	1.300 (9)	C14A—C15A	1.382 (6)
N1B—C6B	1.452 (12)	C15A—H15A	0.9300
N1B—C5B	1.452 (15)	S1B—O11B	1.447 (4)
N1B—H1C	0.8600	S1B—O12B	1.456 (4)
N1B—H1B	0.8600	S1B—O10B	1.460 (4)
C2B—N3B	1.301 (7)	S1B—C14B	1.767 (4)
C2B—C5B	2.013 (16)	O7B—C9B	1.310 (5)
C2B—H2B	0.9300	O7B—H7E	0.8200
N3B—C4B	1.361 (6)	O8B—C9B	1.227 (5)
C4B—N9B	1.339 (6)	O9B—C11B	1.342 (6)
C4B—C5B	1.378 (12)	O9B—H9E	0.8200
C4B—C5C	1.396 (12)	C9B—C10B	1.466 (6)
O6B—C6B	1.222 (15)	C10B—C15B	1.401 (6)
C5C—N7B	1.425 (13)	C10B—C11B	1.405 (6)
C5C—C6B	1.458 (18)	C11B—C12B	1.399 (7)
C5C—C8B	2.009 (15)	C12B—C13B	1.366 (7)
O6C—C6C	1.227 (16)	C12B—H12B	0.9300
C5B—C6C	1.41 (2)	C13B—C14B	1.401 (6)
C6C—N7B	1.476 (14)	C13B—H13B	0.9300
N7B—C8B	1.319 (9)	C14B—C15B	1.383 (6)
N7B—H7B	0.8600	C15B—H15B	0.9300
N7B—H7C	0.8600	O1W—H1WA	0.8501
C8B—N9B	1.301 (7)	O1W—H1WB	0.8493
C8B—H8B	0.9300	O2W—H2WA	0.821 (10)
N9B—H9B	0.8600	O2W—H2WB	0.820 (10)
S1A—O11A	1.439 (4)

C2A—N1A—C6A	125.2 (4)	N9B—C8B—C5C	74.8 (5)
C2A—N1A—H1A	117.4	N7B—C8B—C5C	45.0 (4)
C6A—N1A—H1A	117.4	N9B—C8B—H8B	120.1
C2A—N3A—C4A	112.2 (4)	N7B—C8B—H8B	120.1
C8A—N7A—C5A	107.1 (4)	C5C—C8B—H8B	165.1
C8A—N7A—H7A	126.4	C8B—N9B—C4B	109.5 (5)
C5A—N7A—H7A	126.4	C8B—N9B—H9B	125.2
C8A—N9A—C4A	107.7 (4)	C4B—N9B—H9B	125.2
C8A—N9A—H9A	126.1	O11A—S1A—O12A	112.6 (2)
C4A—N9A—H9A	126.1	O11A—S1A—O10A	113.0 (2)
N3A—C2A—N1A	125.4 (4)	O12A—S1A—O10A	111.8 (2)
N3A—C2A—H2A	117.3	O11A—S1A—C14A	106.4 (2)
N1A—C2A—H2A	117.3	O12A—S1A—C14A	106.0 (2)
C5A—C4A—N3A	126.3 (4)	O10A—S1A—C14A	106.4 (2)
C5A—C4A—N9A	107.5 (4)	C9A—O7A—H7D	109.5
N3A—C4A—N9A	126.2 (4)	C11A—O9A—H9D	109.5
C4A—C5A—N7A	107.5 (4)	O8A—C9A—O7A	122.1 (4)
C4A—C5A—C6A	121.5 (4)	O8A—C9A—C10A	123.6 (4)
N7A—C5A—C6A	131.0 (4)	O7A—C9A—C10A	114.2 (4)
O6A—C6A—N1A	121.4 (4)	C15A—C10A—C11A	119.5 (4)
O6A—C6A—C5A	129.1 (4)	C15A—C10A—C9A	121.1 (4)
N1A—C6A—C5A	109.5 (4)	C11A—C10A—C9A	119.4 (4)
N7A—C8A—N9A	110.1 (4)	O9A—C11A—C12A	116.8 (4)
N7A—C8A—H8A	125.0	O9A—C11A—C10A	123.8 (4)
N9A—C8A—H8A	125.0	C12A—C11A—C10A	119.4 (4)
C2B—N1B—C6B	137.0 (7)	C13A—C12A—C11A	120.5 (4)
C2B—N1B—C5B	93.9 (7)	C13A—C12A—H12A	119.8
C2B—N1B—H1C	111.5	C11A—C12A—H12A	119.8
C6B—N1B—H1C	111.5	C12A—C13A—C14A	120.2 (4)
C2B—N1B—H1B	133.1	C12A—C13A—H13A	119.9
C5B—N1B—H1B	133.1	C14A—C13A—H13A	119.9
N1B—C2B—N3B	121.5 (6)	C15A—C14A—C13A	119.7 (4)
N1B—C2B—C5B	46.0 (5)	C15A—C14A—S1A	121.3 (3)
N3B—C2B—C5B	75.5 (5)	C13A—C14A—S1A	119.0 (3)
N1B—C2B—H2B	119.3	C14A—C15A—C10A	120.7 (4)
N3B—C2B—H2B	119.3	C14A—C15A—H15A	119.6
C5B—C2B—H2B	165.3	C10A—C15A—H15A	119.6
C2B—N3B—C4B	107.9 (5)	O11B—S1B—O12B	112.8 (3)
N9B—C4B—N3B	126.2 (5)	O11B—S1B—O10B	112.5 (2)
N9B—C4B—C5B	133.4 (8)	O12B—S1B—O10B	111.5 (2)
N3B—C4B—C5B	100.4 (7)	O11B—S1B—C14B	106.2 (2)
N9B—C4B—C5C	99.5 (7)	O12B—S1B—C14B	107.3 (2)
N3B—C4B—C5C	134.3 (7)	O10B—S1B—C14B	106.1 (2)
C4B—C5C—N7B	117.1 (10)	C9B—O7B—H7E	109.5
C4B—C5C—C6B	117.7 (10)	C11B—O9B—H9E	109.5
N7B—C5C—C6B	125.2 (10)	O8B—C9B—O7B	122.7 (4)
C4B—C5C—C8B	76.2 (6)	O8B—C9B—C10B	122.9 (4)
N7B—C5C—C8B	40.9 (5)	O7B—C9B—C10B	114.4 (4)
C6B—C5C—C8B	166.0 (9)	C15B—C10B—C11B	119.4 (4)
O6B—C6B—N1B	136.7 (11)	C15B—C10B—C9B	121.3 (4)
O6B—C6B—C5C	121.8 (11)	C11B—C10B—C9B	119.3 (4)
N1B—C6B—C5C	101.5 (8)	O9B—C11B—C12B	117.6 (4)
C4B—C5B—C6C	120.4 (12)	O9B—C11B—C10B	122.8 (4)
C4B—C5B—N1B	116.4 (10)	C12B—C11B—C10B	119.6 (4)
C6C—C5B—N1B	123.2 (10)	C13B—C12B—C11B	120.5 (4)
C4B—C5B—C2B	76.3 (7)	C13B—C12B—H12B	119.8
C6C—C5B—C2B	163.3 (10)	C11B—C12B—H12B	119.8
N1B—C5B—C2B	40.1 (5)	C12B—C13B—C14B	120.5 (4)
O6C—C6C—C5B	126.6 (13)	C12B—C13B—H13B	119.8
O6C—C6C—N7B	132.2 (13)	C14B—C13B—H13B	119.8
C5B—C6C—N7B	101.2 (8)	C15B—C14B—C13B	119.8 (4)
C8B—N7B—C5C	94.1 (7)	C15B—C14B—S1B	120.8 (3)
C8B—N7B—C6C	135.6 (7)	C13B—C14B—S1B	119.4 (3)
C8B—N7B—H7B	133.0	C14B—C15B—C10B	120.2 (4)
C5C—N7B—H7B	133.0	C14B—C15B—H15B	119.9
C8B—N7B—H7C	112.2	C10B—C15B—H15B	119.9
C6C—N7B—H7C	112.2	H1WA—O1W—H1WB	104.5
N9B—C8B—N7B	119.8 (6)	H2WA—O2W—H2WB	112 (10)

C4A—N3A—C2A—N1A	0.3 (7)	C6B—C5C—N7B—C8B	178.1 (9)
C6A—N1A—C2A—N3A	−0.5 (8)	O6C—C6C—N7B—C8B	178.6 (13)
C2A—N3A—C4A—C5A	0.0 (7)	C5B—C6C—N7B—C8B	−2.0 (12)
C2A—N3A—C4A—N9A	−179.1 (4)	C5C—N7B—C8B—N9B	0.3 (8)
C8A—N9A—C4A—C5A	−0.4 (5)	C6C—N7B—C8B—N9B	2.6 (12)
C8A—N9A—C4A—N3A	179.0 (4)	N7B—C8B—N9B—C4B	−0.6 (8)
N3A—C4A—C5A—N7A	−179.2 (4)	C5C—C8B—N9B—C4B	−0.4 (5)
N9A—C4A—C5A—N7A	0.1 (5)	N3B—C4B—N9B—C8B	178.7 (5)
N3A—C4A—C5A—C6A	−0.1 (7)	C5B—C4B—N9B—C8B	−1.3 (10)
N9A—C4A—C5A—C6A	179.2 (4)	C5C—C4B—N9B—C8B	0.5 (7)
C8A—N7A—C5A—C4A	0.2 (5)	O8A—C9A—C10A—C15A	179.1 (5)
C8A—N7A—C5A—C6A	−178.8 (5)	O7A—C9A—C10A—C15A	1.1 (6)
C2A—N1A—C6A—O6A	−179.1 (5)	O8A—C9A—C10A—C11A	−0.3 (7)
C2A—N1A—C6A—C5A	0.4 (6)	O7A—C9A—C10A—C11A	−178.2 (4)
C4A—C5A—C6A—O6A	179.4 (5)	C15A—C10A—C11A—O9A	−180.0 (4)
N7A—C5A—C6A—O6A	−1.7 (9)	C9A—C10A—C11A—O9A	−0.6 (7)
C4A—C5A—C6A—N1A	−0.1 (6)	C15A—C10A—C11A—C12A	−1.3 (7)
N7A—C5A—C6A—N1A	178.7 (4)	C9A—C10A—C11A—C12A	178.1 (4)
C5A—N7A—C8A—N9A	−0.4 (6)	O9A—C11A—C12A—C13A	179.2 (5)
C4A—N9A—C8A—N7A	0.5 (6)	C10A—C11A—C12A—C13A	0.4 (7)
C6B—N1B—C2B—N3B	0.6 (12)	C11A—C12A—C13A—C14A	0.6 (8)
C5B—N1B—C2B—N3B	−0.6 (8)	C12A—C13A—C14A—C15A	−0.8 (7)
N1B—C2B—N3B—C4B	0.6 (8)	C12A—C13A—C14A—S1A	178.7 (4)
C5B—C2B—N3B—C4B	0.2 (5)	O11A—S1A—C14A—C15A	116.8 (4)
C2B—N3B—C4B—N9B	179.7 (5)	O12A—S1A—C14A—C15A	−3.4 (5)
C2B—N3B—C4B—C5B	−0.2 (7)	O10A—S1A—C14A—C15A	−122.5 (4)
C2B—N3B—C4B—C5C	−2.7 (10)	O11A—S1A—C14A—C13A	−62.7 (4)
N9B—C4B—C5C—N7B	−0.4 (9)	O12A—S1A—C14A—C13A	177.2 (4)
N3B—C4B—C5C—N7B	−178.3 (6)	O10A—S1A—C14A—C13A	58.0 (4)
N9B—C4B—C5C—C6B	−178.6 (8)	C13A—C14A—C15A—C10A	−0.1 (7)
N3B—C4B—C5C—C6B	3.4 (13)	S1A—C14A—C15A—C10A	−179.6 (3)
N9B—C4B—C5C—C8B	−0.3 (4)	C11A—C10A—C15A—C14A	1.1 (7)
N3B—C4B—C5C—C8B	−178.3 (6)	C9A—C10A—C15A—C14A	−178.2 (4)
C2B—N1B—C6B—O6B	−177.8 (13)	O8B—C9B—C10B—C15B	179.5 (5)
C2B—N1B—C6B—C5C	−0.1 (12)	O7B—C9B—C10B—C15B	−1.8 (6)
C4B—C5C—C6B—O6B	176.7 (11)	O8B—C9B—C10B—C11B	−2.8 (7)
N7B—C5C—C6B—O6B	−1.4 (17)	O7B—C9B—C10B—C11B	175.9 (4)
C8B—C5C—C6B—O6B	4 (4)	C15B—C10B—C11B—O9B	179.4 (4)
C4B—C5C—C6B—N1B	−1.5 (11)	C9B—C10B—C11B—O9B	1.6 (7)
N7B—C5C—C6B—N1B	−179.6 (8)	C15B—C10B—C11B—C12B	0.0 (7)
C8B—C5C—C6B—N1B	−174 (3)	C9B—C10B—C11B—C12B	−177.8 (5)
N9B—C4B—C5B—C6C	1.7 (14)	O9B—C11B—C12B—C13B	−178.9 (5)
N3B—C4B—C5B—C6C	−178.4 (9)	C10B—C11B—C12B—C13B	0.5 (8)
N9B—C4B—C5B—N1B	179.9 (6)	C11B—C12B—C13B—C14B	−1.1 (8)
N3B—C4B—C5B—N1B	−0.1 (9)	C12B—C13B—C14B—C15B	1.2 (7)
N9B—C4B—C5B—C2B	−179.8 (6)	C12B—C13B—C14B—S1B	−177.9 (4)
N3B—C4B—C5B—C2B	0.1 (4)	O11B—S1B—C14B—C15B	−114.7 (4)
C2B—N1B—C5B—C4B	0.4 (9)	O12B—S1B—C14B—C15B	6.0 (5)
C2B—N1B—C5B—C6C	178.6 (9)	O10B—S1B—C14B—C15B	125.3 (4)
C4B—C5B—C6C—O6C	179.4 (12)	O11B—S1B—C14B—C13B	64.3 (4)
N1B—C5B—C6C—O6C	1.2 (19)	O12B—S1B—C14B—C13B	−174.9 (4)
C2B—C5B—C6C—O6C	4 (4)	O10B—S1B—C14B—C13B	−55.6 (4)
C4B—C5B—C6C—N7B	0.0 (12)	C13B—C14B—C15B—C10B	−0.6 (7)
N1B—C5B—C6C—N7B	−178.2 (8)	S1B—C14B—C15B—C10B	178.4 (3)
C2B—C5B—C6C—N7B	−175 (3)	C11B—C10B—C15B—C14B	0.0 (7)
C4B—C5C—N7B—C8B	0.1 (9)	C9B—C10B—C15B—C14B	177.8 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N7B—H7B···O3WAⁱ	0.86	2.26	3.08	158
O7A—H7D···O10Aⁱⁱ	0.82	1.86	2.677	170
O7B—H7E···O10Bⁱ	0.82	1.84	2.655	175
O9A—H9D···O12Bⁱⁱ	0.82	2.34	2.924	128
O9B—H9E···O12Aⁱⁱⁱ	0.82	2.54	3.143	131
O1W—H1WA···O6A^iv	0.85	2.31	2.801	117
O1W—H1WA···O10B^iv	0.85	2.28	2.917	132
N9B—H9B···O6B^v	0.86	2.42	3.044	130
N9B—H9B···O3WA^vi	0.86	2.47	3.07	128
N1A—H1A···O6A^vii	0.86	2.05	2.898	170
N1B—H1C···O4W	0.86	2.22	2.890	135
N1B—H1C···O11A	0.86	2.45	2.998	122
O1W—H1WB···O12B	0.85	2.01	2.844	169
O2W—H2WA···N3A	0.83	2.07	2.849	157
O2W—H2WB···O12A	0.82	2.03	2.815	160
N7A—H7A···O1W	0.86	1.77	2.615	168
N9A—H9A···O2W	0.86	1.89	2.697	157
C2A—H2A···O1Wⁱⁱ	0.93	2.43	3.149	134
C2B—H2B···O11A	0.93	2.46	2.974	114
C8A—H8A···O2W^viii	0.93	2.40	3.310	167
C15B—H15B···O9A	0.93	2.59	3.510	172

Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z; (iii) x+1, y, z−1; (iv) −x+1, −y+1, −z+1; (v) x, −y+1/2, z−1/2; (vi) x+1, −y+1/2, z−1/2; (vii) −x, −y+1, −z+1; (viii) −x+1, −y+1, −z+2.

6-Oxo-1,9-dihydropurin-7-ium perchlorate monohydrate (II) top

Crystal data top

C₅H₅N₄O⁺·ClO₄⁻·H₂O	F(000) = 520
M_r = 254.60	D_x = 1.833 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 5.0307 (6) Å	Cell parameters from 2752 reflections
b = 20.386 (2) Å	θ = 2.0–30.3°
c = 9.0181 (10) Å	µ = 0.44 mm⁻¹
β = 94.233 (2)°	T = 296 K
V = 922.33 (18) Å³	Plate, colourless
Z = 4	0.45 × 0.02 × 0.003 mm

Data collection top

Bruker APEXII CCD diffractometer	2370 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.025
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θ_max = 30.3°, θ_min = 2.0°
T_min = 0.957, T_max = 1.000	h = −7→7
16360 measured reflections	k = −28→28
2752 independent reflections	l = −12→12

Refinement top

Refinement on F²	3 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.038	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.111	w = 1/[σ²(F_o²) + (0.0576P)² + 0.3728P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
2752 reflections	Δρ_max = 0.37 e Å⁻³
165 parameters	Δρ_min = −0.29 e Å⁻³

Special details top

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

	x	y	z	U_iso*/U_eq
Cl1	1.32826 (7)	0.47612 (2)	0.23036 (5)	0.03437 (13)
O6	1.1975 (2)	0.28099 (6)	0.28926 (13)	0.0395 (3)
O2	1.2250 (4)	0.53538 (8)	0.1690 (2)	0.0699 (5)
O3	1.6141 (3)	0.47706 (8)	0.2342 (2)	0.0627 (4)
O4	1.2288 (3)	0.42071 (7)	0.14577 (18)	0.0571 (4)
O5	1.2456 (3)	0.46991 (8)	0.37946 (17)	0.0598 (4)
N1	0.9409 (3)	0.35230 (6)	0.41720 (15)	0.0334 (3)
H1	1.018 (4)	0.3843 (12)	0.387 (3)	0.049 (6)*
N7	0.8829 (2)	0.17434 (6)	0.43852 (14)	0.0281 (3)
H7	0.992 (5)	0.1492 (12)	0.387 (3)	0.060 (7)*
N9	0.5789 (2)	0.20049 (6)	0.58838 (14)	0.0284 (3)
H9	0.462 (5)	0.1993 (11)	0.650 (3)	0.046 (6)*
C2	0.7509 (3)	0.36488 (7)	0.51258 (18)	0.0342 (3)
H2	0.716229	0.408591	0.533422	0.041*
N3	0.6127 (3)	0.32029 (6)	0.57756 (14)	0.0312 (3)
C4	0.6819 (3)	0.25866 (7)	0.53983 (15)	0.0246 (3)
C5	0.8730 (3)	0.24168 (7)	0.44524 (15)	0.0243 (3)
C6	1.0223 (3)	0.29051 (7)	0.37512 (16)	0.0272 (3)
C8	0.7053 (3)	0.15077 (7)	0.52526 (17)	0.0311 (3)
H8	0.672604	0.106462	0.540420	0.037*
O1W	0.2214 (3)	0.38054 (6)	0.76425 (18)	0.0511 (4)
H1W	0.252 (5)	0.4216 (5)	0.765 (3)	0.066 (7)*
H2W	0.344 (4)	0.3627 (10)	0.718 (3)	0.081 (9)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0347 (2)	0.02074 (17)	0.0495 (2)	−0.00172 (12)	0.01561 (16)	−0.00075 (13)
O6	0.0398 (6)	0.0391 (6)	0.0428 (6)	−0.0012 (5)	0.0248 (5)	0.0054 (5)
O2	0.0807 (12)	0.0369 (7)	0.0952 (13)	0.0172 (7)	0.0277 (10)	0.0222 (8)
O3	0.0351 (7)	0.0545 (9)	0.1004 (13)	−0.0050 (6)	0.0182 (7)	−0.0109 (8)
O4	0.0551 (8)	0.0419 (8)	0.0757 (10)	−0.0102 (6)	0.0147 (7)	−0.0226 (7)
O5	0.0734 (10)	0.0587 (9)	0.0503 (8)	−0.0211 (8)	0.0244 (7)	−0.0040 (6)
N1	0.0377 (7)	0.0255 (6)	0.0388 (7)	−0.0043 (5)	0.0146 (5)	0.0030 (5)
N7	0.0305 (6)	0.0236 (5)	0.0317 (6)	0.0031 (4)	0.0130 (5)	0.0006 (4)
N9	0.0282 (6)	0.0285 (6)	0.0304 (6)	−0.0020 (4)	0.0141 (5)	0.0016 (4)
C2	0.0410 (8)	0.0242 (6)	0.0385 (8)	0.0007 (6)	0.0120 (6)	−0.0031 (6)
N3	0.0331 (6)	0.0269 (6)	0.0351 (6)	0.0024 (5)	0.0132 (5)	−0.0026 (5)
C4	0.0233 (6)	0.0261 (6)	0.0254 (6)	−0.0003 (5)	0.0075 (5)	0.0005 (5)
C5	0.0246 (6)	0.0241 (6)	0.0251 (6)	0.0007 (5)	0.0085 (5)	0.0023 (5)
C6	0.0269 (6)	0.0279 (6)	0.0277 (6)	−0.0020 (5)	0.0083 (5)	0.0032 (5)
C8	0.0338 (7)	0.0245 (6)	0.0367 (7)	−0.0007 (5)	0.0128 (6)	0.0022 (5)
O1W	0.0546 (8)	0.0302 (6)	0.0739 (9)	−0.0081 (6)	0.0417 (7)	−0.0050 (6)

Geometric parameters (Å, º) top

Cl1—O2	1.4116 (15)	N9—C8	1.3452 (19)
Cl1—O4	1.4324 (13)	N9—C4	1.3784 (17)
Cl1—O3	1.4359 (15)	N9—H9	0.84 (2)
Cl1—O5	1.4421 (15)	C2—N3	1.309 (2)
O6—C6	1.2307 (17)	C2—H2	0.9300
N1—C2	1.357 (2)	N3—C4	1.3539 (18)
N1—C6	1.3860 (19)	C4—C5	1.3758 (17)
N1—H1	0.82 (2)	C5—C6	1.4229 (18)
N7—C8	1.3204 (18)	C8—H8	0.9300
N7—C5	1.3752 (18)	O1W—H1W	0.852 (9)
N7—H7	0.90 (3)	O1W—H2W	0.850 (9)

O2—Cl1—O4	111.24 (12)	N3—C2—H2	117.4
O2—Cl1—O3	109.68 (11)	N1—C2—H2	117.4
O4—Cl1—O3	109.46 (9)	C2—N3—C4	112.14 (12)
O2—Cl1—O5	108.50 (11)	N3—C4—C5	126.43 (12)
O4—Cl1—O5	108.29 (9)	N3—C4—N9	127.50 (12)
O3—Cl1—O5	109.63 (11)	C5—C4—N9	106.07 (12)
C2—N1—C6	125.56 (13)	N7—C5—C4	107.91 (11)
C2—N1—H1	115.8 (16)	N7—C5—C6	131.06 (12)
C6—N1—H1	118.5 (16)	C4—C5—C6	121.02 (13)
C8—N7—C5	108.00 (12)	O6—C6—N1	123.73 (13)
C8—N7—H7	124.0 (16)	O6—C6—C5	126.53 (14)
C5—N7—H7	128.0 (16)	N1—C6—C5	109.75 (12)
C8—N9—C4	108.26 (11)	N7—C8—N9	109.76 (12)
C8—N9—H9	129.5 (15)	N7—C8—H8	125.1
C4—N9—H9	122.2 (15)	N9—C8—H8	125.1
N3—C2—N1	125.11 (14)	H1W—O1W—H2W	106.9 (14)

C6—N1—C2—N3	−1.1 (3)	N3—C4—C5—C6	0.0 (2)
N1—C2—N3—C4	0.5 (2)	N9—C4—C5—C6	−179.54 (13)
C2—N3—C4—C5	0.0 (2)	C2—N1—C6—O6	−179.27 (16)
C2—N3—C4—N9	179.42 (15)	C2—N1—C6—C5	1.0 (2)
C8—N9—C4—N3	−179.25 (14)	N7—C5—C6—O6	0.6 (3)
C8—N9—C4—C5	0.24 (16)	C4—C5—C6—O6	179.83 (15)
C8—N7—C5—C4	0.01 (17)	N7—C5—C6—N1	−179.65 (14)
C8—N7—C5—C6	179.31 (15)	C4—C5—C6—N1	−0.4 (2)
N3—C4—C5—N7	179.34 (14)	C5—N7—C8—N9	0.15 (18)
N9—C4—C5—N7	−0.15 (15)	C4—N9—C8—N7	−0.24 (18)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4	0.82	2.60	3.249	138
N1—H1···O5	0.82	2.09	2.879	162
N7—H7···O2ⁱ	0.91	2.60	3.031	110.2
N7—H7···O1Wⁱⁱ	0.91	1.76	2.6489	165
N9—H9···O6ⁱⁱⁱ	0.84	1.93	2.7602	166
O1W—H1W···O3^iv	0.85	2.17	3.018	172
O1W—H2W···N3	0.85	2.11	2.951	172
C8—H8···O2ⁱ	0.93	2.47	2.970	114
C8—H8···O3ⁱⁱⁱ	0.93	2.47	3.268	144
C8—H8···O4ⁱⁱⁱ	0.93	2.55	3.072	116

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

Comparison of salt forms of purine derivatives containing halides/nitrate/phosphite/phosphate/sulfate and perchlorates as anions top

Compound	Space group	Primary interaction between	Graph-set motif	Motif type	Secondary interaction between	Graph-set motif	Motif type
Guaninidinium hydrochloride	Monoclinic P2₁/c,	N—H···N, N—H···O	R₂²(8),	IV and V	N—H···Cl,	R₃²(8),	XII and XIII
	a = 4.479 Å		R₂²(10)		C—H···Cl,	R₄³(11)
	b = 9.995 Å				O—H···N,
	c = 19.304 Å				O—H···Cl
	β = 107.90°
Guaninidinium hydrobromide	Monoclinic P2₁/c	N—H···N, N—H···O	R₂²(8),	IV and V	N—H···Br,	R₃²(8),	XII and XIII
	a = 4.8708 Å		R₂²(10)		N—H···N,	R₄³(11)
	b = 13.237 Å				O—H···Br,
	c = 14.638 Å				C—H···Br
	β = 93.906°
Guaninidinium dinitrate dihydrate	Monoclinic P2₁/c	N—H···O	R₂²(8)	V	N—H···O,	R₄³(12)	XII
	a = 6.6340 Å				O—H···O
	b = 10.2020 Å
	c = 11.0440 Å
	β = 106.04°
Guaninidinium phosphite monohydrate	Monoclinic P2₁/c	N—H···N	R₂²(8)	IV	N—H···O	R₂¹(6),	XII and XVIII
	a = 4.9700 Å					R₄³(10)
	b = 12.7506 Å
	c = 15.0499 Å
	β = 92.293°
Guaninidinium phosphite dihydrate form (I)	Monoclinic P2₁/c	N—H···N	R₂²(8)	IV	N—H···N,	R₃²(8),	XIII and XVIII
	a = 4.6812 Å				N—H···O	R₂¹(6)
	b = 24.0561 Å
	c = 9.5186 Å
	β = 99.773°
Guaninidinium phosphite dihydrate form (II)	Monoclinic P2₁/c	N—H···N	R₂²(8)	IV	N—H···N,	R₃²(8),	XIII and XVIII
	a = 4.7340 Å				N—H···O	R₂¹(6)
	b = 24.0450 Å
	c = 9.5050 Å
	β = 98.860°
Guaninidinium phosphate hydrate form (I)	Triclinic, P1	N—H···N	R₂²(8)	IV	N—H···O,	R₂²(9)	XVI and XVII
	a = 9.607 Å				O—H···O	R₂²(10)
	b = 10.221 Å
	c = 10.603 Å
	α = 84.5°
	β = 108.2°
	γ = 119.7°
Guaninidinium phosphate monohydrate form (II)	Monoclinic P2₁/n	N—H···N	R₂²(8)	IV	N—H···O,	R₂²(8),	VI, XIII and XVI
	a = 4.5414 Å				O—H···O	R₃²(8),
	b = 12.5774 Å					R₂²(9)
	c = 18.1485 Å
	β = 93.689 °
Guaninidinium sulfate monohydrate	Monoclinic P2₁/c	N—H···O	R₂²(8)	VI	N—H···O, O-H···O	R₄³(12)	XV
	a = 8.9940 Å
	b = 10.2020 Å
	c = 11.0440 Å
	β = 106.04°
Xanthinium nitrate monohydrate	Triclinic, P1	N—H···O	R₂²(8)	I	O—H···N,	R₂²(4),	VIII, XI and XIII
	a = 5.0416 Å				O—H···O	R₃²(8),
	b = 7.4621 Å					R₆⁴(14)
	c = 12.1396 Å
	α = 80.248°
	β = 80.800°
	γ = 75.657°
Xanthinium sulfate monohydrate	Monoclinic P2₁	N—H···O	R₂²(8)	I	O—H···N,	R₃²(8)	XIII
	a = 5.183 Å
	b = 24.805 Å
	c = 7.701 Å
	β = 103.510°
Xanthinium perchlorate dihydrate	Triclinic, P1	N—H···O	R₂²(8)	I	O—H···N,	R₃²(8)	XIII
	a = 5.1625 Å				O—H···O
	b = 7.7449 Å
	c = 13.696 Å
	α = 100.214°
	β = 91.591°
	γ = 100.880°
Hypoxanthinium hydrochloride monohydrate	Monoclinic P2₁/c	N—H···Cl	R₃²(9)	III	N—H···Cl,	R₃³(11),	IX, X and XI
	a = 4.8295 Å				C—H···Cl,	R₄⁴(16),
	b = 17.7285 Å				O—H···N,	R₆⁴(14)
	c = 9.0077 Å				O—H···Cl
	β = 94.59°
Hypoxanthinium nitrate monohydrate form (I)	Orthorhombic Pnma	N—H···O	R₂²(8)	II	N—H···O,	R₂²(6),	XIII and XIV
	a = 13.701 Å				O—H···O,	R₃²(8),
	b = 6.236 Å					R₆⁶(20)
	c = 10.078 Å
Hypoxanthinium nitrate monohydrate form (II)	Monoclinic P2₁/n	N—H···O	R₂²(8)	II	N—H···O,	R₂²(6),	XIII and XIV
	a = 6.1452 Å				O—H···O,	R₃²(8)
	b = 13.7517 Å
	c = 10.0414 Å
	β = 95.601°

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Volume 78| Part 6| June 2022| Pages 574-583

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research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Crystal structures and Hirshfeld surface analyses of hypoxanthine salts involving 5-sulfosalicylate and perchlorate anions

1. Chemical context

2. Structural commentary

3. Supra­molecular features

4. Hirshfeld surface analysis

5. Comparison with the structures of related compounds

6. Synthesis and crystallization

7. Refinement

Supporting information

References

research communications

3. Supramolecular features