Reactions of radical anions. Part XV. An electron spin resonance study of the radical anions derived from cis- and trans-1,2-bis(diphenylphosphinyl)ethylene

Abstract

The radical anions produced by the passage of tetrahydrofuran or 2-methyltetrahydrofuran solutions of cis- or trans-1,2-bis(diphenylphosphinyl)ethylene (DPPE) over various alkali metal films at –80° have been studied. Their production occurs by a two-stage process (i) and (ii). Computer simulation of the e.s.r. spectra together Ph₂P–CHCH–PPh₂ [graphic omitted] –CHCH–[graphic omitted] + 2PhM (i), [graphic omitted]–CHCH–[graphic omitted][[graphic omitted]CHCH[graphic omitted]]^–˙M⁺(ii) with chemical evidence show that the radical anion produced is as in equation (ii). The e.s.r. spectra also show that the unpaired electron is delocalised over the whole molecule. The nature of the e.s.r. spectra was dependent on the metal used. When Cs⁺ was the gegenion, metal splitting due to two caesium ions was observed. We find no metal splitting for the third Cs⁺ ion. The radical anion produced from cis-DPPE was the same as that from trans-DPPE.