The metathesis reactions of [SNS][SbF6] and [SN][AsF6] with Li[Al(OC(CF3)3)4] in liquid SO2

The small di- and triatomic molecules [SN]+ and [SNS]+ have shown versatile chemistries and [SNS]+ is an important starting reagent for many sulfur–nitrogen radicals. However, their chemistry is limited to the more polar solvents (e.g. SO2). In this work an attempt is made to increase their solubility in less polar solvents by exchange of the usual [MF6]− (M = As, Sb) anions by the large and weakly coordinating [Al(OC(CF3)3)4]−. As expected the metathesis reactions of [SN][AsF6] and [SNS][SbF6] with Li[Al(OC(CF3)3)4] in liquid sulfur dioxide resulted in the formation of the insoluble Li[SbF6], which is the driving force for these metathesis reactions. The characterization of the compounds by IR and multinuclear NMR revealed that [SNS]+ formed a [Al(OC(CF3)3)4]− salt in a clean reaction. A preliminary crystal structure of [SNS][Al(OC(CF3)3)4] is presented. The solubility of [SNS][Al(OC(CF3)3)4] in CH2Cl2 is significantly increased with respect to the corresponding [MF6]− salts, and potentially opens up new areas of [SNS]+ chemistry. The reaction of the more reactive [SN]+ with Li[Al(OC(CF3)3)4] was less clear. Multinuclear NMR and IR spectra were consistent with the formation of [SN][Al(OC(CF3)3)4], which also showed significant decomposition.

Graphical abstractMetathesis reactions in liquid sulphur dioxide of [SNS][SbF6] and [SN][AsF6] with Li[Al(OC(CF3)3)3]. Figure optionsDownload full-size imageDownload as PowerPoint slide