Crystal structure of the β-form of tetra-arsenic trisulphide

Abstract

The crystal structure of synthetic β-dimorphite, As₄S₃, has been determined by a three-dimensional single-crystal X-ray study from photographic data. Crystals are orthorhombic, space group Pnma, with Z= 4 in a unit cell of dimensions a= 11·21 ± 0·02, b= 9·90 ± 0·02, and c= 6·58 ± 0·01 Å. The structure is built of As₄S₃ molecules similar to those observed for α-dimorphite. The structure was solved by Patterson and Fourier methods and refined by least squares to R 0·09 for 438 observed reflections.