electronic structures of dimolybdenum compounds; detailed electronic absorption and electrochemical studies of dimolybdenum BAII complexes

The complexes Mo2(OAc)3(BAII), where BAII is 1,3-bis(arylimino)isoindoline, have been synthesized. A detailed interpretation of their 1H-NMR spectra has been made. The structure of the bis(pyridylimino)isoindoline derivative has been determined by X-ray analysis to facilitate the assignment of the resonance lines in the spectra. It has been found that there are trends in energies and intensities of the delta-->delta* transition in these compounds. Electron withdrawing substituents on the aromatic nitrogen heterocycles in BAII shift the delta-->delta* transition to a lower energy and a higher intensity as compared to electron releasing substituents. These trends suggest that mixing of M-->L charge transfer transitions with the delta-->delta* transitions is occurring in these compounds which is consistent with the results of electrochemical trends in oxidation potentials. The complexes which are hardest to oxidize in general have the lowest delta-->delta* transition.