Effect of a series of phosphine and phosphite ligands on the Taft substituent constants of arenechromiumcarbonyl and cyclopentadienylmanganesecarbonyl complexes

Abstract

A series of m- and p-fluorophenylarenechromiumcarbonyl and m- and p-fluorophenylcyclopentadienylmanganesecarbonyl complexes of phosphines and phosphites have been prepared and characterized by IR and NMR spectroscopy. Taft substituent constants were calculated from the 19F chemical shifts and carbonyl stretching force constants were calculated from the carbonyl stretching frequencies of the compounds. It has been found that the phosphine and phosphite groups exert parallel effects on the Taft constants and stretching force constants and, furthermore, that the trends in the chromium and manganese series are strongly related.