The crystal structure of triphenylarsine sulphide

Abstract

Crystals of AsPh₃S obtained from acetone solution are monoclinic, space group P2₁/c, Z= 8, with unit-cell dimensions a= 18.523(8), b= 9.642(4), c= 18.140(8)Å, and β= 105.93(4)°. The compound is isomorphous with PPh₃S and PPh₃Se. The structure has been elucidated on the basis of this isomorphism, from 2 795 observed reflections and refined to R 0.042 2. The AsS bond is essentially a double bond, and in both molecules of the asymmetric unit one phenyl ring lies almost coplanar with the As–S bond, while the other rings have an average torsion angle of 53°. The molecular structure is compared with those of PPh₃S and PPh₃Se in an attempt to elucidate the reasons for the observed conformations.