Effect of fluorine and trifluoromethyl substitution on the donor properties and stereodynamical behaviour of triarylphosphines

Abstract

A series of 2-, 3- or 4-trifluoromethyl substituted triarylphosphines and their oxide, chalcogenide and Fe(CO)₄ derivatives have been prepared and characterised spectroscopically and crystallographically. Electronic effects of CF₃ substitution are cumulative and felt equally in the 2, 3 or 4 position. Substitution in the 2 position substantially hinders the complexing ability for steric reasons. Correlated P–C rotation in the 2-substituted derivatives has been analysed by variable temperature NMR and molecular mechanics calculations.