Correlations of 95Mo NMR chemical shifts with ligand basicity in substituted pyridine pentacarbonylmolybdenum(O) complexes

Abstract Molybdenum-95 NMR chemical shifts are reported for a series of Mo(O) compounds of the type Mo(CO) 5 L (L = pyridine derivatives). A good correlation is found between the δ( 95 Mo) values and the Hammett sigma constant of the pyridine substituent or the p K a of the substituted pyridine. The chemical shift values, which range from −1366 ppm (3-CN, σ = 0.62, p K a = 1.35) to −1433 ppm (4-NMe 2 , σ = −0.83, p K a = 9.61), directly reflect the electronic properties of the pyridine derivatives even though the substituent is four or five bonds away from the molybdenum atom.