A Direct Determination of the Crystal Structure of Ethylenediammonium Sulphate

Abstract

The Harker-Kasper inequality method was applied successfully to determine most of the signs of structure factors of ethylene diammonium sulphate. Starting from these signs the final Fourier projections on (001) and (100) were obtained. The dimensions of the unit cell containing eight formula units are a=8.47±0.02 A, c=18.03±0.04 A, and the space group is D₄⁴–C4₁22₁ or D₄⁸–C4₃22₁. The ethylenediammonium group is of gauche type with an azimuthal angle of 75.7° . The hydrogen bond distances found in this crystal are 2.80 A, 2.81 A, and 2.82 A. The existence of only one kind of two mirror-image configurations of the ethylenediammonium ion in one of the enantiomorphous forms of this crystal may be an important cause of the strong optical rotatory power of the crystal.