AN IMPROVED SYNTHESIS OF SF5(CN) AND ITS CYCLOADDITION REACTION WITH SNSASF6 - CRYSTAL-STRUCTURE OF F5SCNSNSASF6 AND ELECTRON-SPIN-RESONANCE SPECTRUM OF F5SCNSNS

An improved synthesis of SF5(CN), by direct fluorination of SF3(CN), h as been achieved. This product forms a stable adduct at low temperatur e 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 an d F-19 Fourier-transform NMR spectroscopy and by its dissociation vapo ur-pressure curve. The salt SNSAsF6 and an excess of SF5(CN) reacted i n sulfur dioxide solution to give the stable salt F5SCNSNSAsF6 which h as been characterized by vibrational, F-19 NMR and mass spectroscopy a nd X-ray crystallography. The structure consists of discrete F5SCNSNS cations and AsF6- anions. The mass spectrum of F5SCNSNSAsF6 was consi stent with loss of AsF5 and fluoride ion transfer to give F5SCNSNSF wh ich dissociated to SF4 and F2CNSNS. Reduction of a dilute solution of the salt in SO2 led to identification (ESR spectroscopy) of the radica l F5SCNSNS..