Mueller, Gerhard; Lutz, Martin; Harder, Sjoerd:

Methyl group conformation-determining intermolecular C-H...O hydrogen bonds: structure of N-methyl-2-pyrrolidone.

In: Acta Crystallographica, Section B: Structural Science, Jg. B52 (1996) ; Nr. 6, S. 1014-1022
ISSN: 0108-7681
Zeitschriftenaufsatz / Fach: Chemie
Abstract:
N-methyl-2-pyrrolidone at 168 K is monoclinic space group P21/c, a 6.221(3), b 12.976(2), c 7.529(4) .ANG., b 111.03(2) Deg; Z = 4, dc = 1.24; R = 0.058 for 1190 reflections. At. coordinates are given. It adopts a slightly puckered ring conformation in the solid state, which is intermediate between a twist and an envelope conformation. The N-Me group takes part in two almost linear intermol. C-H...hydrogen H bonds to neighboring keto groups, which cause a notable deviation from its usually preferred conformation with one C-H bond being almost eclipsed to the adjacent N-C amide bond. These findings are substantiated by force-field and high-level ab initio calcns. on isolated mols.