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]˙.