Abstract: | A systematic study has been made of the effects of substituent induced chemical shifts in [(η5-C5H5)(CO)3Mo(CH2C6H4R)] compounds. Both 95Mo and 13C NMR shifts in the aromatic ring are reported. The (η5-C5H5)(CO)3MoCH2? group is a reasonably strong resonance donor (σR° = ?0.21) and weak inductive donor (σI = ?0.07). The molybdenum chemical shifts are extremely sensitive to the effects of distant substituents (range c. 40 ppm). Since the shift correlates well with substituent constants in this series, it is suggested that the chemical shift is controlled by the paramagnetic term for this spin 5/2 nucleus. |