The crystal structure of malonic acid

Abstract

At room temperature malonie acid, COOH.CIt~.COOH, is triclinic; a = 5.33 /~, b---5.14 ~, c ---- 11.25 A, a ---- 102 ° 42', fl ---- 135 ° 10' 7 ---- 85° 10', Z = 2. On the basis of space group Pi good agreement between photographically observed and calculated intensities was obtained. Molecules are arranged in zigzag chains along the c axis, with the carboxyl groups linked through two hy- drogen bonds as in the higher dicarboxylic acids. Unlike those, however, only one of the carboxyl groups is approximately coplanar with the carbon atoms. The significance of this is discussed.