Crystal structures ofN-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (monoclinic polymorph) andN-(pyridin-4-ylmethyl)pyrazine-2-carboxamide

Abstract

The title compounds, C11H10N4O (HL1) and C11H10N4O (HL2), are pyridine 2-ylmethyl and 4-ylmethyl derivatives, respectively, of pyrazine-2-carboxamide. HL1 was measured at 153 K and crystallized in the monoclinic space groupP21/cwithZ= 4. There has been a report of the same structure measured at room temperature but assumed to crystallize in the triclinic space groupP-1 withZ= 4 [Sasanet al.(2008).Monatsh. Chem.139, 773–780]. In HL1, the pyridine ring is inclined to the pyrazine ring by 61.34 (6)°, while in HL2 this dihedral angle is 84.33 (12)°. In both molecules, there is a short N—H...N interaction involving the pyrazine carboxamide unit. In the crystal of HL1, molecules are linked by N—H...N hydrogen bonds, forming inversion dimers with anR22(10) ring motif. The dimers are linkedviabifurcated-acceptor C—H...O hydrogen bonds, forming sheets lying parallel to (102). The sheets are linkedviaC—H...N hydrogen bonds, forming a three-dimensional structure. In the crystal of HL2, molecules are linked by N—H...N and C—H...N hydrogen bonds to form chains propagating along [010]. The chains are linkedviaC—H...O hydrogen bonds, forming sheets lying parallel to (100). Within the sheets there are π–π interactions involving neighbouring pyrazine rings [inter-centroid distance = 3.711 (15) Å]. Adjacent sheets are linkedviaparallel slipped π–π interactions involving inversion-related pyridine rings [inter-centroid distance = 3.6395 (17) Å], forming a three-dimensional structure.