Preparation of bis-(N-alkyl-N-diphenylphosphinoamino)phenylphosphines and their reactions with sulphur and methyl iodide

Abstract

Bis-(N-alkyl-N-diphenylphosphinoamino)phenylphosphines,[Ph₂P·N(R)·]₂PPh (R = Me or Et), have been synthesised from chlorodiphenylphosphine and NN′-dialkylaminophenylphosphines with triethylamine as a hydrogen chloride acceptor. Mono-(R = Et), di-(R = Me or Et), and tri-sulphides (R = Me or Et) of these phosphines have been isolated and ¹H n.m.r. spectroscopy has been used to show that sulphuration takes place preferentially at the terminal phosphorus atoms when R = Me. When R = Me or Et, only one phosphorus atom has been quaternised in each case by methyl iodide. Bands arising from the P–N stretching modes are assigned in the i.r. spectra of their derivatives.