2,6-Dimethylpyrazine at 20 K: a neutron-diffraction study

Abstract

Single crystal neutron diffraction techniques are used to determine the crystal structure of 2,6‐di­methyl­pyrazine (DMP), C6H8N2, at 20 K. The space group is P21/a with Z = 4, as at room temperature. The methyl groups are ordered. There are two crystallographically inequivalent methyl groups in the unit cell.

2,6-Dimethylpyrazine at 5 K: a neutron-diffraction study

“…As found for the structure of this material, (I), at 20 K (Kaiser-Morris et al, 2001), the space group is P2 1 /a (monoclinic) with four molecules per unit cell. There is no evidence for any phase transition between 20 and 5 K, and no significant changes of the lattice parameters below 20 K.…”

“…The structure consists of parallel layers of planar molecules perpendicular to the (201) plane (Kaiser-Morris et al, 2001). The protons of the methyl groups are quite localized at all temperatures.…”

“…The molecular structure of (I) at 5 K, with 50% probability displacement ellipsoids. For a packing diagram, see the preceding paper(Kaiser-Morris et al, 2001). …”

X-ray diffraction and inelastic neutron scattering study of 2,6-dimethylpyrazine (DMP) chloranilic acid (CLA) complex

“…The crystal structure of neat DMP was determined by single crystal neutron diffraction at temperatures 5 K [7] and 20 K [8]. At both temperatures the system was evidenced to be monoclinic with space group P2 1 /a and four molecules in the unit cell.…”