An improved synthesis of SF5(CN) and its cycloaddition reaction with SNSAsF6. Crystal structure of F5SCNSNSAsF6 and electron spin resonance spectrum of F5SCNSNS?

Abstract

An improved synthesis of SF5(CN), by direct fluorination of SF3(CN), has been achieved. This product forms a stable adduct at low temperature with AsF5, and addition of MeCN to this adduct led to very pure SF5(CN). The SF5(CN)·AsF5 adduct has been characterized by vibrational and 19F Fourier-transform NMR spectroscopy and by its dissociation vapour-pressure curve. The salt SNSAsF6 and an excess of SF5(CN) reacted in sulfur dioxide solution to give the stable salt F5S[graphic omitted]AsF6 which has been characterized by vibrational, 19F NMR and mass spectroscopy and X-ray crystallography. The structure consists of discrete F5S[graphic omitted]+ cations and AsF6– anions. The mass spectrum of F5S[graphic omitted]AsF6 was consistent with loss of AsF5 and fluoride ion transfer to give F5S[graphic omitted] which dissociated to SF4 and F2[graphic omitted]. Reduction of a dilute solution of the salt in SO2 led to identification (ESR spectroscopy) of the radical F5S[graphic omitted]˙.