Conformational analysis of malonic acid and its derivatives: ab initio, CNDO/2 and empirical calculations

Theoretical conformational analysis of malonic acid and α-substituted derivatives has been performed by ab initio, CNDO/2 and PEM (Partition of the Energy Method) techniques. For malonic acid, a high conformational flexibility, not substantially modified by the α-substitution, is predicted. Owing to the high flexibility, intermolecular interactions play an important role in determining the crystal state conformations of these compounds. The agreement between X-ray data and theoretical results is discussed. © 1977.