Crystal structure of dipotassium pentasulphide

Abstract

Crystals of K₂S₅ are orthorhombic, space group P2₁2₁2₁ with Z= 4 in a unit cell of dimensions: a= 6.494(1), b= 6.600(2), c= 17.414(5)Å. The structure has been elucidated by vector methods from 656 independent diffracted intensities measured on a four-circle diffractometer and refined to R 0.045. The [S₅]^2– anion exists as a contorted but unbranched chain in which successive S–S bond lengths are 2.037, 2.074, 2.075, and 2.050(5)Å, and the bond angles are close to tetrahedral. The torsions in the chain around the S(2)–(3) and S(3)–S(4) bonds are 74 and 69° respectively. The potassium ions are evenly distributed between the S₅ units with minimum K ⋯ S 3.215(4)Å, and a nearest-neighbour K ⋯ K of just under 4 Å.