Magnetic and electrochemical investigations on anions derived from oligoketones containing fluorenone and benzophenone units. An approach to the design of stable multiradical organic materials

Abstract

The mono- and poly-anions of some mono-, di- and tetra-ketones containing fluorenone and benzophenone moieties have been studied by NMR and cyclic voltammetry. Alkali metal anion radicals of fluorenone, generated by electron transfer from an alkali metal naphthalene radical anion exhibit markedly lower molar paramagnetic solvent shifts than those generated by direct reduction with an alkali metal. Evidence is provided for the involvement of hyperfine interactions between the naphthalene and the paramagnetic solute. The dianion of the diketone 9 is paramagnetic as are the dianions of the tetraketones 6 and 7. The NMR data, combined with those obtained by cyclic voltammetry, indicate that polyketones possessing fluorenone moieties connected through isophthaloyl ‘spacers’ are promising systems for the preparation of high-spin organics and electrophores.