¹⁹F and ¹³C NMR studies of some pentafluorophenylantimony  (III and V) derivatives

Abstract

¹⁹F and ¹³C NMR studies on a number of pentafluorophenylantimony(III and V) compounds of the type (C₆F₅)nSbX_3-n,(C₆F₅)nSbX_5-nand C₆F₅SbBr₂CI₂(X=Cl or Br; n=1-3) have shown that the chemical shift values mainly depend on the oxidation state of antimony (III and V). A marginal yet distinct effect on chemical shift has been noticed due to electronegativity difference of halogens (Br, CI) attached to antimony. The results show standard spin-spin interaction of fluorine atoms with respect to 0-, m- and p-phenyl positions in ring as well as expected chemical shift due to <em>p</em>p - <em>d</em>p: interaction of fluorinated benzene ring and antimony. The fluorine of a-position is profusely influenced in comparison to that at <em>p</em>- and <em>m</em>-positions. The fluorine signals in oxidation state (III) derivative appear at lower field in comparison to those for oxidation state (V) compounds. The additive effects of anions and pentafluorophenyl rings seem to be negligible.