Notes. Oxidation and reduction of phosphorus–phosphorus and arsenic–arsenic double bonds. An electrochemical study of two diphosphenes and a diarsene

Abstract

The diphosphenes [(Me₃Si)₃C]₂P₂(1) and (2,4,6-Bu^t₃C₆H₂)₂P₂(2) and the diarsene [(Me₃Si)₃C]₂As₂(3) undergo electrochemical reduction in tetrahydrofuran (thf) solution to the corresponding anion radicals [{(Me₃Si)₂C}₂P₂]˙^–(4), [(2,4,6-Bu^t₃C₆H₂)₂P₂]˙^–(5), and [{(Me₃Si)₃C}₂As₂]˙^–(6), respectively. Anion radicals (4) and (5) were sufficiently stable to permit the acquisition of e.s.r. data. The products of oxidation of (1), (2), and (3) were much more difficult to characterise. The oxidation of (1) in CH₂Cl₂, is irreversible at 25 °C; however, at –75 °C a one-electron oxidation occurs to the unstable cation radical [{(Me₃Si)₃C}₂P₂]˙⁺. The oxidation of both (2) and (3) is irreversible even at –75 °C.