2,3,5,6-Tetrakis{[(pyridin-2-yl)sulfanyl]methyl}pyrazine

Abstract

The title compound, C 28 H 24 N 6 S 4 , synthesized by the reaction of 2,3,5,6-tetrakis(bromomethyl)pyrazine with 2-mercaptopyridine, crystallizes with one half-molecule in the asymmetric unit. The whole molecule is generated by inversion symmetry, the centre of the pyrazine ring being located about an inversion centre. The pyridine rings of the unique (pyridin-2-ylsulfanyl)methyl substituents are inclined to the pyrazine ring by 38.7 (3) and 75.6 (2) , and by 66.0 (3) to one another. In the crystal, molecules are linked via C-HÁ Á Á interactions, forming chains along the b-axis direction. The chains are linked by offset -interactions [intercentroid distance = 3.682 (3) Å ], forming layers lying parallel to the bc plane. Structure descriptionThe title compound is one of a series of tetra-substituted pyrazine compounds (Pacifico & Stoeckli-Evans, 2004;Assoumatine et al., 2007;Assoumatine & Stoeckli-Evans, 2014a), prepared in order to study their coordination behaviour with various transition metals (Assoumatine, 1999). It was synthesized by the reaction of 2,3,5,6-tetrakis(bromomethyl)pyrazine (Assoumatine & Stoeckli-Evans, 2014b), with 2-mercaptopyridine. The synthesis and crystal structure of 2,3,5,6-tetrakis(bromomethyl)pyrazine have been reported (Assoumatine & Stoeckli-Evans, 2014b).The title compound, crystallizes with one half-molecule in the asymmetric unit (Fig. 1). The whole molecule is generated by inversion symmetry, the centre of the pyrazine ring being located about an inversion centre. The pyridine rings (N2/C4-C8 and N3/C10-C14) of the unique (pyridin-2-ylsulfanyl)methyl substituents are inclined to the pyrazine ring by 38.7 (3) and 75.6 (2) , respectively, and by 66.0 (3) to one another. In the phenyl analogue of the title compound, viz. 2,3,5,6-tetrakis[(phenylsulfanyl)methyl]pyrazine Keywords: crystal structure; tetrakis-substituted; pyrazine; pyridin-2-ylsulfanyl derivative; inversion symmetry; C-HÁ Á Á interactions; offsetinteractions. CCDC reference: 1521950Structural data: full structural data are available from iucrdata.iucr.org Synthesis and crystallizationTo a magnetically stirred solution of 2-mercaptopyridine (4 g, 35.4 mmol; Aldrich, 99%) in CH 2 Cl 2 (100 ml), were added 2,3,5,6-tetrakis(bromomethyl)pyrazine (4 g, 8.85 mmol) and triethylamine (5 ml, 35.4 mmol; Fluka, 99.5%). The contents were heated at reflux for 30 min, cooled to room temperature, and diluted with CH 2 Cl 2 (100 ml). The organic solution was washed with water (3 Â 30 ml) and a saturated solution of NaCl (1 Â 30 ml), dried over anhydrous MgSO 4 and evaporated to dryness on a rotary evaporator after filtration. The resultant yellowish residue was recrystallized from acetonitrile solution and dried under vacuum to afford the title compound (yield 4.56 g, 90%; m.p. 422-423 K). R f 0.48 (solvent CH 2 Cl 2 , eluent CHCl 3 /MeCO 2 Et, 7/5 v/v). Pale-yellow blocks were prepared by diffusion of an equal volume of ethanol into a concentrated CHCl 3 (4 ml) solution of the title compound. Spectroscopic and analytical data:...