The diphosphaallene radical anion: EPR and theoretical investigations

Liquid phase EPR spectra of a diphosphaallenic radical anion have been recorded after electrochemical reduction of a solution of ArPCPAr in THF at 293 K (Ar = 2,4,6-But3C6H2). The hyperfine coupling interactions of two 31P and one 13C nuclei (in the case of Ar13CPAr) are discussed in the light of AM1 calculations carried out on (ArPCPAr)˙–, of ab initio calculations performed on the model radical anion (HPCPH)˙– at the MP2 and MCSCF levels of theory and of DFT calculations on (HPCPH)˙–. The structure of the radical anion is compared with that of the neutral molecule.