2,2′-Di­thio­bis­pyrazine: about the di­sulfide bond

X-ray diffraction studies reveal that pyrazine-2-thiol undergoes condensation to 2,2′-di­thio­bis­pyrazine [systematic name: 2-(pyrazin-2-yldisulfanyl)pyrazine], C₈H₆N₄S₂ (I), under aerial conditions. In the mol­ecule of I, the pyrazine rings are arranged in an almost perpendicular manner, with an absolute value of the C—S—S—C torsion angle of −91.45 (6)°. A search in the Cambridge Structural Database confirmed that such a conformation is typical for di­sulfide com­pounds. Three different rotamers of di­sulfide I were studied using quantum theoretical studies. The rotamer of lowest energy was observed in the crystalline state in the structure stabilized by hydrogen-bond, chalcogen-bond and stacking inter­actions. Further quantum chemical com­putations confirm that 2,2′-di­thio­bis­pyrazine can react according to the S_N2 mechanism.

Computing details

Data collection: CrysAlis PRO (Rigaku OD, 2020); cell refinement: CrysAlis PRO (Rigaku OD, 2020); data reduction: CrysAlis PRO (Rigaku OD, 2020); program(s) used to solve structure: SHELXT2018 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

2-(Pyrazin-2-yldisulfanyl)pyrazine

Crystal data

C8H6N4S2	Z = 2
Mr = 222.29	F(000) = 228
Triclinic, P1	Dx = 1.550 Mg m^−3
a = 5.6832 (1) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.4639 (2) Å	Cell parameters from 6130 reflections
c = 11.7473 (3) Å	θ = 2.8–29.2°
α = 91.524 (2)°	µ = 0.52 mm^−1
β = 95.245 (2)°	T = 293 K
γ = 106.024 (2)°	Cut plate, yellow
V = 476.24 (2) Å^3	0.24 × 0.08 × 0.03 mm

Data collection

Rigaku XtaLAB Synergy Dualflex diffractometer with a HyPix detector	2551 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source	1990 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.032
Detector resolution: 10.0000 pixels mm^-1	θmax = 31.1°, θmin = 2.8°
ω scans	h = −7→7
Absorption correction: gaussian (CrysAlis PRO; Rigaku OD, 2020)	k = −10→10
Tmin = 0.646, Tmax = 1.000	l = −16→16
13219 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.032	H-atom parameters constrained
wR(F^2) = 0.087	w = 1/[σ^2(Fo^2) + (0.0388P)^2 + 0.0599P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
2551 reflections	Δρmax = 0.24 e Å^−3
127 parameters	Δρmin = −0.26 e Å^−3
0 restraints

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.

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

	x	y	z	Uiso*/Ueq
S12A	0.88777 (8)	0.82515 (5)	0.24527 (3)	0.05535 (14)
S12	0.51768 (8)	0.75339 (6)	0.21054 (3)	0.05632 (14)
N11A	1.1678 (2)	0.85466 (18)	0.43568 (11)	0.0534 (3)
N11	0.5985 (2)	0.42008 (18)	0.16399 (12)	0.0542 (3)
N14A	0.8155 (3)	0.6392 (2)	0.56361 (12)	0.0586 (3)
N14	0.1119 (2)	0.2607 (2)	0.07399 (12)	0.0613 (4)
C12	0.4351 (3)	0.5157 (2)	0.15903 (11)	0.0416 (3)
C12A	0.9380 (3)	0.77714 (18)	0.39184 (12)	0.0435 (3)
C13A	0.7614 (3)	0.6697 (2)	0.45469 (13)	0.0512 (4)
H13A	0.602192	0.618027	0.420052	0.061*
C15	0.2761 (3)	0.1648 (2)	0.07863 (13)	0.0531 (4)
H15	0.227497	0.040696	0.051216	0.064*
C13	0.1918 (3)	0.4365 (2)	0.11467 (13)	0.0558 (4)
H13	0.082179	0.508859	0.113540	0.067*
C16A	1.2209 (3)	0.8212 (2)	0.54463 (15)	0.0591 (4)
H16A	1.380639	0.871281	0.579086	0.071*
C16	0.5152 (3)	0.2425 (2)	0.12250 (15)	0.0574 (4)
H16	0.623987	0.169461	0.123587	0.069*
C15A	1.0470 (3)	0.7152 (2)	0.60712 (14)	0.0589 (4)
H15A	1.092551	0.695813	0.682846	0.071*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S12A	0.0613 (3)	0.0465 (2)	0.0493 (2)	−0.00156 (17)	0.01245 (17)	0.00042 (15)
S12	0.0651 (3)	0.0501 (2)	0.0575 (2)	0.02468 (19)	0.00036 (18)	−0.00203 (17)
N11A	0.0421 (7)	0.0502 (7)	0.0609 (8)	0.0008 (5)	0.0103 (5)	−0.0097 (6)
N11	0.0383 (7)	0.0471 (7)	0.0743 (8)	0.0114 (5)	−0.0045 (6)	−0.0062 (6)
N14A	0.0550 (8)	0.0572 (8)	0.0553 (7)	0.0016 (6)	0.0059 (6)	0.0074 (6)
N14	0.0394 (7)	0.0701 (9)	0.0683 (8)	0.0094 (6)	−0.0052 (6)	−0.0069 (7)
C12	0.0414 (7)	0.0488 (7)	0.0364 (6)	0.0151 (6)	0.0041 (5)	0.0044 (5)
C12A	0.0441 (8)	0.0329 (6)	0.0497 (7)	0.0039 (5)	0.0089 (6)	−0.0047 (5)
C13A	0.0425 (8)	0.0489 (8)	0.0540 (8)	−0.0005 (6)	0.0042 (6)	0.0040 (6)
C15	0.0444 (8)	0.0508 (8)	0.0573 (8)	0.0033 (7)	0.0037 (6)	−0.0045 (7)
C13	0.0415 (8)	0.0699 (11)	0.0592 (9)	0.0237 (8)	−0.0027 (6)	−0.0004 (8)
C16A	0.0432 (8)	0.0613 (10)	0.0672 (10)	0.0089 (7)	−0.0017 (7)	−0.0119 (8)
C16	0.0424 (8)	0.0472 (8)	0.0815 (11)	0.0141 (7)	−0.0015 (7)	−0.0068 (7)
C15A	0.0591 (10)	0.0608 (10)	0.0537 (9)	0.0144 (8)	−0.0015 (7)	−0.0011 (7)

Geometric parameters (Å, º)

S12A—S12	2.0216 (6)	C12—C13	1.391 (2)
S12A—C12A	1.7816 (14)	C12A—C13A	1.385 (2)
S12—C12	1.7792 (15)	C13A—H13A	0.9300
N11A—C12A	1.3227 (19)	C15—H15	0.9300
N11A—C16A	1.334 (2)	C15—C16	1.367 (2)
N11—C12	1.3166 (19)	C13—H13	0.9300
N11—C16	1.340 (2)	C16A—H16A	0.9300
N14A—C13A	1.329 (2)	C16A—C15A	1.369 (3)
N14A—C15A	1.328 (2)	C16—H16	0.9300
N14—C15	1.321 (2)	C15A—H15A	0.9300
N14—C13	1.324 (2)
C12A—S12A—S12	104.70 (5)	N14—C15—H15	119.0
C12—S12—S12A	104.87 (5)	N14—C15—C16	122.02 (15)
C12A—N11A—C16A	115.79 (13)	C16—C15—H15	119.0
C12—N11—C16	115.54 (13)	N14—C13—C12	121.76 (15)
C15A—N14A—C13A	116.19 (14)	N14—C13—H13	119.1
C15—N14—C13	116.23 (13)	C12—C13—H13	119.1
N11—C12—S12	120.89 (11)	N11A—C16A—H16A	119.1
N11—C12—C13	122.03 (14)	N11A—C16A—C15A	121.84 (15)
C13—C12—S12	117.08 (11)	C15A—C16A—H16A	119.1
N11A—C12A—S12A	112.32 (10)	N11—C16—C15	122.42 (15)
N11A—C12A—C13A	122.57 (13)	N11—C16—H16	118.8
C13A—C12A—S12A	125.10 (11)	C15—C16—H16	118.8
N14A—C13A—C12A	121.17 (14)	N14A—C15A—C16A	122.42 (15)
N14A—C13A—H13A	119.4	N14A—C15A—H15A	118.8
C12A—C13A—H13A	119.4	C16A—C15A—H15A	118.8
S12A—S12—C12—N11	8.43 (12)	C12—N11—C16—C15	−0.5 (2)
S12A—S12—C12—C13	−172.07 (10)	C12A—N11A—C16A—C15A	−0.8 (2)
S12A—C12A—C13A—N14A	179.24 (12)	C13A—N14A—C15A—C16A	0.8 (3)
S12—S12A—C12A—N11A	−165.73 (10)	C15—N14—C13—C12	0.4 (2)
S12—S12A—C12A—C13A	15.01 (14)	C13—N14—C15—C16	−0.2 (2)
S12—C12—C13—N14	179.87 (13)	C16A—N11A—C12A—S12A	−178.51 (11)
N11A—C12A—C13A—N14A	0.0 (2)	C16A—N11A—C12A—C13A	0.8 (2)
N11A—C16A—C15A—N14A	0.1 (3)	C16—N11—C12—S12	−179.90 (12)
N11—C12—C13—N14	−0.6 (2)	C16—N11—C12—C13	0.6 (2)
N14—C15—C16—N11	0.3 (3)	C15A—N14A—C13A—C12A	−0.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C13A—H13A···S12	0.93	2.74	3.2220 (16)	113
C13A—H13A···N14A^i	0.93	2.64	3.433 (2)	144

Symmetry code: (i) −x+1, −y+1, −z+1.