Oxidation of [Li4{(NBut)3S}2]: a new route to sulfur triimides‡

Abstract

The oxidation reactions of [Li₄{(NBu^t)₃S}₂] with oxygen and halogens (bromine and iodine) were investigated. In all these reactions a radical intermediate [Li₃{(NBu^t)₃S}₂]˙ was observed, which was investigated by ESR spectroscopy. While the reaction with oxygen leads to the dianionic sulfur(VI) species [Li₂(NBu^t)₃SO], oxidation with halogens yields N,N′,N″-tris(tert-butyl)sulfur triimide S(NBu^t)₃. The latter reaction provides an easy access to sulfur triimides. Some intermediates from the reaction of [Li₄{(NBu^t)₃S}₂] with halogens could be isolated and characterised by X-ray structure analyses. The intermediates can be rationalised as adducts of a lithium halide and a monomeric [Li₂(NBu^t)₂S] unit to give [(thf)₃Li₃(µ₃-X){(NBu^t)₃S}] (X = Br or I). In the presence of oxygen the oxidation reaction of [Li₄{(NBu^t)₃S}₂] with iodine affords an adduct of lithium iodide and the sulfate analogue [(thf)₃Li₃(µ₃-I){(NBu^t)₃SO}] is obtained. As revealed by X-ray structure analysis, this adduct is very similar to [(thf)₃Li₃(µ₃-I){(NBu^t)₃S}] in the solid state.