Preparation and ESR of phosphorus spiro compounds. Part III

Abstract

Abstract. The synthesis of 2,2'-biphenylenediphenylphosphonium, 2,2'-biphenylenephenyIbenzylphosphonium and 2,2'-biphenylenephenyl(p-nitrophenyl)phosphonium salts is described. The related phosphoranyl radicals I, IV and V, generated by electrochemical reduction, are measured by ESR spectroscopy. A similar procedure is followed for the radicals I1 and 111; related phosphonium compounds are described in the literature. The small values of the phosphorus doublet splitting constants are an indication for a tetrahedron (T) like configuration of the phosphorus. The odd electron is delocalized in the aromatic ligands and the five 3-d orbitals of the phosphorus. It is shown that the spin-and odd electron density distribution depends on the electron affinity of the aryl ligands. This is confirmed by quantum chemical calculations.

The Gold(I)‐Mediated Domino Reaction to Fused Diphenyl Phosphoniumfluorenes: Mechanistic Consequences for Gold‐Catalyzed Hydroarylations and Application in Solar Cells

“…A generally accepted synthesis of phosphonium salts is the addition of a fourth substituent to a trivalent phosphane by nucleophilic substitution. However, although the installation of a methyl or benzyl substituent is relatively simple, the coupling of an aryl substituent is challenging. It requires the catalytic employment of palladium or nickel, or stoichiometric reactions with in situ generated arynes or aryl radicals .…”