Oxidative addition and isomerization reactions. The synthesis of cis- and trans-ArSF4Cl and cis- and trans-PhTeF4Cl

Abstract

The stereoselective synthesis and isomerization of cis- and trans-ArSF4Cl is described, where Ar = Ph, p-MeC6H4, and p--O2NC6H4. Also briefly described is the synthesis of ArSF5, cis- and trans-PhTeF4Cl, and PhTeF5. The oxidative halogenating reagent is a mixture of XeF2 and Cl−, and suitable starting compounds are ArSSAr, ArSF3, and PhTeTePh. Products were characterized by 19F, 13C, and 125Te NMR spectroscopy, and by the 37Cl/35Cl and 34S/32S isotope effects on the 19F NMR chemical shifts. A mechanism of oxidative halogenation is proposed to account for the stereoselective synthesis of cis- and trans-ArSF4Cl. Ab initio calculations of optimized geometries of anionic and radical intermediates, i.e., PhSF3X− and PhSF3X• (X = F, Cl), were carried out with the aid of the GAUSSIAN 92 program. Key words: synthesis of cis- and trans-ArSF4Cl, cis- and trans-PhTeF4Cl, ArSF5, and PhTeF5, mechanism of oxidative fluorination and oxidative chlorination, 37Cl/35Cl and 34S/32S isotope effects on 19F NMR spectra.