2,2′-Disulfanediylbis(pyridine N-oxide)–hydrogen peroxide (1/1)

In the title co-crystal, C₁₀H₈N₂O₂S₂·H₂O₂, both mol­ecules are generated by crystallographic twofold symmetry; the dihedral angle between the pyridine rings is 101.16 (9)°. In the crystal, the components are linked by O—H⋯O hydrogen bonds to generate [010] chains of alternating 2,2′-di­thio­bis­(pyridine N-oxide) and hydrogen peroxide mol­ecules. The structure was refined as a two-component inversion twin.

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Chemical scheme

Structure description

The anti­fungal and anti­bacterial properties of the bis­pyri­thione family have made the compound 2,2′-di­thio­bis­(pyridine N-oxide) of inter­est for many years (O'Donnell et al., 2009; Paulus, 1993; Zhang et al., 2001). A number of reports on the improved synthesis of the di­thio­bis compound have also been reported (e.g. Li et al., 2012).

The title compound, C₁₀H₈N₂O₂S₂^.H₂O₂, is a co-crystal (Fig. 1) formed via a hydrogen-bonding network inter­linking the di­thio­bis­(pyridine N-oxide) mol­ecules with a C₂²(12) assembly. The hydrogen bond is formed between the peroxide OH moiety and the pyridine N-oxide O atom with O⋯O = 2.672 (3) Å (Table 1). The hydrogen bonding network generates [010] chains (Fig. 2) of alternating di­thio­bis­(pyridine N-oxide) and hydrogen peroxide mol­ecules. The O2—O2ⁱⁱ and S1—S1ⁱ bond distances are 1.454 (4) and 2.067 (2) Å, respectively [symmetry codes: (i) 1 – x, –y, z; (ii) 1–x, 1 – y, z]. Both the hydrogen peroxide and the di­sulfide mol­ecules are generated by crystallographic twofold symmetry. The torsion angle between the pyridine N-oxide rings is slightly greater than perpendicular at 101.16 (9)°. The torsion angle C1—S1—S1ⁱ—C1ⁱ that bridges the pyridine rings is slighly less at 100.43 (13)°.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯O1	0.95 (3)	1.73 (3)	2.672 (3)	174 (3)

Figure 1 A view of the mol­ecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) −x + 1, −y + 1, z; (ii) 1 − x, 1 − y, z.]

Figure 2 Crystal packing diagram of title compound viewed along [001]. Hydrogen bonds are colored red.

The hydrogen peroxide H2A—O2—O2ⁱⁱ—H2Aⁱⁱ torsion angle is equal to 133.86 (7)°. Similar compounds have been observed to have this torsion angle much closer to 90°. For example the hydrogen peroxide torsion angle in the (Z)-N-benzyl­idene-1-phenyl-methanamine oxide solvate is reported to be 88° (Churakov et al., 2017) while a piperizine N-oxide derivative (Ravikumar et al., 2005) is found to be 90°. Similar torsion angles of 101° and lower have been observed in phosphine oxide hydrogen peroxide adducts (see for example Ahn et al., 2015). This large angle can be attributed to the lowest energy confirmation imposed by the solid-state supra­molecular structure where the O1⋯O2—O2ⁱⁱ⋯O1ⁱⁱ pseudo torsion angle (via the hydrogen bonds) is 140.06 (6)°.

Synthesis and crystallization

The title compound was synthesized by modification of the literature procedure (Bernstein & Losee, 1956): 2.0 g of 2-pyridine­thiol-N-oxide was dissolved in 15 ml of water. To this was slowly added 1.9 ml of 30% hydrogen peroxide. The reaction mixture was stirred for 1 h and a white solid was collected by filtration. The white solid was determined to be 2,2′-di­thio­bis­(pyridine N-oxide) as confirmed by ¹H NMR and melting point. The filtrate was allowed to stand for 4 days, at which time colorless prisms of the title compound were collected in a yield of 12%.

Refinement

Crystal data, data collection, and structure refinement details are summarized in Table 2. The structure was refined with inversion twinning as the Flack parameter indicated racemic twinning.

Table 2
Experimental details

Crystal data
Chemical formula	C10H8N2O2S2·H2O2
Mr	286.32
Crystal system, space group	Orthorhombic, P21212
Temperature (K)	173
a, b, c (Å)	11.232 (2), 12.283 (3), 4.401 (1)
V (Å^3)	607.2 (2)
Z	2
Radiation type	Mo Kα
μ (mm^−1)	0.45
Crystal size (mm)	0.60 × 0.10 × 0.10
Data collection
Diffractometer	Rigaku XtaLAB mini CCD
Absorption correction	Multi-scan (REQAB; Rigaku, 1998)
Tmin, Tmax	0.890, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	6396, 1386, 1316
Rint	0.045
(sin θ/λ)max (Å^−1)	0.648
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.024, 0.059, 1.05
No. of reflections	1386
No. of parameters	87
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å^−3)	0.13, −0.18
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.36 (10)
Computer programs: CrystalClear (Rigaku, 2009), SHELXT (Sheldrick, 2015a), SHELXL (Sheldrick, 2015b) and OLEX2 (Dolomanov et al., 2009).

Structural data

Computing details

Data collection: CrystalClear (Rigaku, 2009); cell refinement: CrystalClear (Rigaku, 2009); data reduction: CrystalClear (Rigaku, 2009); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

2,2'-(Disulfanediyl)bis(pyridine N-oxide)–hydrogen peroxide (1/1)

Crystal data

C10H8N2O2S2·H2O2	Dx = 1.566 Mg m^−3
Mr = 286.32	Mo Kα radiation, λ = 0.71075 Å
Orthorhombic, P21212	Cell parameters from 1941 reflections
a = 11.232 (2) Å	θ = 2.5–27.5°
b = 12.283 (3) Å	µ = 0.45 mm^−1
c = 4.401 (1) Å	T = 173 K
V = 607.2 (2) Å^3	Prism, colorless
Z = 2	0.60 × 0.10 × 0.10 mm
F(000) = 296

Data collection

Rigaku XtaLAB mini CCD diffractometer	1386 independent reflections
Radiation source: Sealed Tube	1316 reflections with I > 2σ(I)
Graphite Monochromator monochromator	Rint = 0.045
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.4°, θmin = 2.5°
profile data from ω–scans	h = −14→14
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	k = −15→15
Tmin = 0.890, Tmax = 1.000	l = −5→5
6396 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.024	w = 1/[σ^2(Fo^2) + (0.025P)^2 + 0.1P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.059	(Δ/σ)max < 0.001
S = 1.05	Δρmax = 0.13 e Å^−3
1386 reflections	Δρmin = −0.18 e Å^−3
87 parameters	Absolute structure: Refined as an inversion twin
0 restraints	Absolute structure parameter: 0.36 (10)
Primary atom site location: structure-invariant direct methods

Special details

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.

Refinement. Refined as a two-component inversion twin. Carbon-bound H-atoms were placed in calculated positions (C—H = 0.95 Å) and were included in the refinement in the riding model approximation,with U_iso(H) set to 1.2U_equiv(C).

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

	x	y	z	Uiso*/Ueq
S1	0.53255 (4)	0.07871 (4)	0.37729 (11)	0.02740 (14)
O1	0.56020 (13)	0.28267 (12)	0.5366 (4)	0.0341 (4)
N1	0.46320 (15)	0.24721 (13)	0.6798 (4)	0.0262 (4)
C1	0.43106 (16)	0.14203 (15)	0.6311 (5)	0.0238 (4)
C2	0.32900 (17)	0.10057 (17)	0.7678 (5)	0.0285 (4)
H2	0.305069	0.029391	0.729631	0.034*
C3	0.2635 (2)	0.16604 (18)	0.9608 (5)	0.0331 (5)
H3	0.195453	0.139037	1.054822	0.040*
C4	0.2999 (2)	0.27245 (19)	1.0134 (5)	0.0352 (5)
H4	0.256619	0.316832	1.144195	0.042*
C5	0.40004 (19)	0.31208 (17)	0.8720 (6)	0.0341 (5)
H5	0.424655	0.383244	0.907584	0.041*
O2	0.56329 (15)	0.48760 (13)	0.3328 (5)	0.0470 (5)
H2A	0.559 (3)	0.417 (2)	0.416 (6)	0.067 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0285 (2)	0.0256 (2)	0.0281 (2)	0.00163 (19)	0.0033 (2)	0.0034 (2)
O1	0.0291 (8)	0.0270 (8)	0.0460 (9)	−0.0033 (6)	0.0009 (7)	0.0068 (7)
N1	0.0260 (8)	0.0239 (8)	0.0286 (8)	0.0002 (7)	−0.0048 (7)	0.0020 (7)
C1	0.0246 (9)	0.0228 (9)	0.0241 (9)	0.0013 (7)	−0.0048 (8)	0.0020 (8)
C2	0.0276 (10)	0.0289 (10)	0.0290 (10)	−0.0025 (8)	−0.0022 (8)	−0.0004 (9)
C3	0.0279 (10)	0.0403 (13)	0.0310 (12)	0.0019 (9)	0.0013 (9)	0.0000 (9)
C4	0.0366 (12)	0.0379 (13)	0.0312 (11)	0.0110 (10)	−0.0020 (9)	−0.0083 (10)
C5	0.0401 (11)	0.0253 (10)	0.0369 (11)	0.0033 (8)	−0.0075 (11)	−0.0054 (10)
O2	0.0433 (9)	0.0287 (9)	0.0688 (11)	0.0072 (7)	0.0155 (9)	0.0110 (9)

Geometric parameters (Å, º)

S1—C1	1.775 (2)	C3—C4	1.389 (4)
S1—S1^i	2.067 (2)	C3—H3	0.9300
O1—N1	1.332 (2)	C4—C5	1.374 (3)
N1—C1	1.358 (3)	C4—H4	0.9300
N1—C5	1.362 (3)	C5—H5	0.9300
C1—C2	1.391 (3)	O2—O2^ii	1.454 (4)
C2—C3	1.382 (3)	O2—H2A	0.95 (3)
C2—H2	0.9300
C1—S1—S1^i	100.52 (9)	C2—C3—C4	119.5 (2)
O1—N1—C1	117.00 (16)	C2—C3—H3	120.2
O1—N1—C5	121.92 (17)	C4—C3—H3	120.2
C1—N1—C5	121.07 (19)	C5—C4—C3	119.9 (2)
N1—C1—C2	119.93 (18)	C5—C4—H4	120.0
N1—C1—S1	110.19 (15)	C3—C4—H4	120.0
C2—C1—S1	129.85 (16)	N1—C5—C4	120.0 (2)
C3—C2—C1	119.5 (2)	N1—C5—H5	120.0
C3—C2—H2	120.3	C4—C5—H5	120.0
C1—C2—H2	120.3	O2^ii—O2—H2A	98.1 (18)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···O1	0.95 (3)	1.73 (3)	2.672 (3)	174 (3)