Kinetics and mechanism of the reaction of trico-ordinate phosphorus compounds with octasulphur

Abstract

Kinetic data and activation Parameters are reported for the reactions of a series of phosphites, arylphosphonites, diarylphosphinites, and triarylphosphines with octasulphur (S₈) in toluene as solvent. For the Phosphites the data are explained in terms of changes in p-character of the lone-pair orbital on Phosphorus and inductive electron donation by the alkyl groups. The rates of reaction of series of arylphosphonites, diarylphosphinites, and triarylphosphines correlate with the Hammett σ constants to give ρ values of –3.0, –3.0, and –2.5, respectively, and the results are discussed in terms of the Reactivity–Selectivity Principle and the biphilic mechanism for insertion of trico-ordinate phosphorus Into σ-bonds.