Epitaxial polymerization of (SN)x: Lattice effects on structures and topochemistry

Abstract

Disulfur dinitride was epitaxially crystallized from the vapor phase on freshly cleaved (100) faces of monovalent alkali halide single crystals. Subsequently, the dimer was polymerized in the solid state, while still on the substrates. This epitaxial polymerization leads to highly oriented crystalline polythiazyl [(SN)x] which shows no evidence of the usual fibrullar morphology. Fibrils of (SN)x have been produced by epitaxial polymerization of a second layer of dimer on a previously polymerized layer. Three new structures of polythiazyl have been observed from crystals grown on NaCl, KBr, and KI. The structures differ significantly from the usual α phase of (SN)x. Because of such large differences in the polymer chain spacing in these forms when compared to the normal form, a new polymerization mode and direction may be involved. The diagnosis of the true effect of water on (SN)x using Fourier-transform infrared spectroscopy (FT-ir) aided in discovering why structural studies from samples exposed to water are impossible.