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 ArP=C=PAr in THF at 293 K (Ar = 2,4,6-(Bu3C6H2)-C-t). The hyperfine coupling interactions of two P-31 and one C-13 nuclei (in the case of Ar=C-13=PAr) are discussed in the light of AM1 calculations carried out on (ArP=C=PAr)(.-), of ab initio calculations performed on the model radical anion (HP=C=PH)(.-) at the MP2 and MCSCF levels of theory and of DFT calculations on (HP=C=PH)(.-). The structure of the radical anion is compared with that of the neutral molecule.