... This difference is in part due to the propensity of the higher valence state of phosphorus, particularly when bound to oxygen, to readily eliminate substituents with ... In 1987, Cherkasov and Polezhaeva 12 and more recently Markovskii et al. ... PF 5 ·PMe 3, −120 b, 784(a), 900(r) b, 47. ...