2,6-Dimethylpyrazine at 5 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 5 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. Different rotational dynamics may account for the two rotational tunnelling transitions observed with inelastic neutron‐scattering techniques.

Amiloride Conformation: The Effect of Different Crystalline Environments

“…This conformation is stabilized by intramolecular hydrogen bonds between O1 and N6, as well as O1 and N4, which are observed also in the crystalline structures. An analysis of the geometry of pyrazine ring has shown the values of bond angles and bond lengths very close to an "average" pyrazine ring parameters for known crystal structures containing this moiety [27][28][29]. The selected bond lengths are shown in Table II and bond angles in Table III.…”

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

“…A precise knowledge of the crystalline structure at the same temperature of the tunnelling measurements is necessary to interpret the INS spectra (Johnson et al, 1996;Johnson et al, 1997;Nicolaï, Kearley et al, 1998). We present in this paper the structure determination at 20 K. The structure at the temperature of the tunnelling experiment, 5 K, is presented in the following article (Kaiser- Morris et al, 2001).…”

“…The crystal structure of (I) at 20 K. For a single molecule representation, see the following paper (Kaiser- Morris et al, 2001). Chebychev polynomial with 5 parameters: 1.04, -3.06, -0.108, -0.644, -0.800 (Carruthers & Watkin, 1979) (Δ/σ) max = 0.007 Δρ max = 0.83 e Å −3 Δρ min = −0.89 e Å −3 Extinction correction: Larson, 1970…”

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.…”