Fluorine resonance spectra of pentafluorophenyl-zinc and -cadmium halides

Abstract

Zinc reacts quantitatively with bromo- and iodo-pentafluorobenzene in a variety of co-ordinating solvents to give solutions of ‘pentafluorophenylzinc halides’. Pentafluorophenyl exchange is normally slow on an n.m.r. time scale at 35°, and equilibrium constants for the Schlenk equilibrium (C₆F₅)₂Zn + ZnX₂⇄ 2C₆F₅ZnX have been obtained from the p-fluorine resonance spectra. Similar results are reported for ‘pentafluorophenylcadmium iodide’ in very strongly co-ordinating solvents. The Schlenk equilibrium for ‘pentafluorophenylzinc chloride’ in tetrahydrofuran has been studied by mixing solutions of zinc chloride and bis (pentafluorophenyl) zinc, and is established within 10 s.