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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 SN2 mechanism.
Supporting information
CCDC reference: 2290145
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
top
Crystal data top
| 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) Å3 | 0.24 × 0.08 × 0.03 mm |
Data collection top
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 top
| Refinement on F2 | Primary atom site location: dual |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.032 | H-atom parameters constrained |
| wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.0388P)2 + 0.0599P]
where P = (Fo2 + 2Fc2)/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 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 | 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 (Å2) top| | U11 | U22 | U33 | U12 | U13 | U23 |
| 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) top
| 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) top
| 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···N14Ai | 0.93 | 2.64 | 3.433 (2) | 144 |
| Symmetry code: (i) −x+1, −y+1, −z+1. |
Comparison of conformers structural parameters: selected torsion and dihedral
angles between pyrazine planes (°);
(I) is the present experimental X-ray data and A, B and C
are conformers obtained in the optimization process at the RI-MP2/def2-TZVPP
level top | (I) | Conformer A | Conformer B | Conformer C |
| C12A—S12A—S12—C12 | -91.5 (1) | -81.20 | -79.12 | -76.02 |
| N11A—C12A—S12A—S12 | -165.73 (10) | -171.60 | -176.65 | 7.13 |
| N11—C12—S12—S12A | 8.43 (12) | 22.24 | -174.94 | 9.26 |
| C13A—C12A—S12A—S12 | 15.01 (14) | 10.01 | 4.89 | -174.32 |
| C13—C12—S12—S12A | -172.07 (10) | -171.60 | 6.76 | -172.23 |
| <(PLN1/PLN2) | 84.0 (3) | 69.55 | 74.71 | 69.54 |
Selected geometrical parameters (Å, °) of the intermolecular interactions
in I top| D—H/S···A | D—H/S | H/S···A | D···A | D—H/S···A |
| C13—H13···N11i | 0.93 | 2.76 | 3.443 (2) | 130.3 |
| C16—H16···N14i | 0.93 | 2.79 | 3.456 (2) | 129.8 |
| C16A—H16A···N11Ai | 0.93 | 2.83 | 3.628 (1) | 144.6 |
| S12A—S12···S12Ai | 2.0216 (6) | 3.819 (2) | – | 152.0 (1) |
| C12A···C15A | – | – | 3.701 (1) | – |
| Symmetry code: (i) x+1, y, z. |
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