Two (E)-2-arylidene-1,4-di-p-tosyl-1,2,3,4-tetrahydroquinoxaline compounds: supramolecular frameworks built with C-H...O and C-H...pi(arene) hydrogen bonds and pi-pi stacking interactions.

The pyrazine ring in two N-substituted quinoxaline derivatives, namely (E)-2-(2-methoxybenzylidene)-1,4-di-p-tosyl-1,2,3,4-tetrahydroquinoxaline, C(30)H(28)N(2)S(2)O(5), (II), and (E)-methyl 2-[(1,4-di-p-tosyl-1,2,3,4-tetrahydroquinoxalin-2-ylidene)methyl]benzoate, C(31)H(28)N(2)S(2)O(6), (III), assumes a half-chair conformation and is shielded by the terminal tosyl groups. In the molecular packing of the compounds, intermolecular C-H...O hydrogen bonds between centrosymmetrically related molecules generate dimeric rings, viz. R(2)(2)(22) in (II) and R(2)(2)(26) in (III), which are further connected through C-H...pi(arene) hydrogen bonds and pi-pi stacking interactions into novel supramolecular frameworks.