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

A series of 2-, 3- or 4-trifluoromethyl substituted triarylphosphines and t heir oxide, chalcogenide and Fe(CO)(4) derivatives have been prepared and c haracterised spectroscopically and crystallographically. Electronic effects of CF3 substitution are cumulative and felt equally in the 2, 3 or 4 posit ion. Substitution in the 2 position substantially hinders the complexing ab ility for steric reasons. Correlated P-C rotation in the 2-substituted deri vatives has been analysed by variable temperature NMR and molecular mechani cs calculations.