Cycloaddition reactions of [SNS][AsF6] with potassium tricyanomethanide

Abstract

The reactions of 1, 2 and 3 equivalents of [SNS][AsF6] with K[C(CN)3] in liquid SO2 generated three cycloaddition products (NC)2C[graphic omitted] 1, [(NC)C([graphic omitted])2][AsF6]2 and [C([graphic omitted])3][AsF6]2·SO23. These were characterised by IR spectroscopy, cyclic voltammetry and elemental analysis. Compounds 1 and 3 were further characterised by 14N and 13C NMR, UV/VIS spectroscopy, X-ray crystallography and (for 1) mass spectroscopy. Compound 1 crystallises as polymeric sheets of dithiadiazole units held together through CN ⋯ S interactions and with a dihedral angle of 117.3° between planes. Compound 3 shows three equivalent [graphic omitted] rings attached to a central carbon atom, the dication possessing C3h symmetry. Molecular orbital calculations were used to deduce a probable reaction mechanism.