Laser Irradiation NMR Studies of Photo-induced Effect on the Ligand Exchange Reactions of Uranium(VI) Complexes

Abstract

A laser irradiation nuclear magnetic resonance (NMR) instrument has been developed for the purpose of measuring high resolution NMR spectra under the irradiation of a laser. The laser irradiation was carried out from the bottom of a sample tube passing through the inside of temperature controller. This instrument first enable us to observe NMR paramagnetic shifts and paramagnetic relaxations resulted from the photo-excitation of diamagnetic metal ions. In this paper, the photo-induced effects on the ligand exchange reactions of various uranium(M)(uranyl) complexes were studied. In bis(acetylacetonato) (dimethyl sulf oxide)uranyl complex, the rate of intramolecular exchange reaction of acetylacetonato ligands was accelerated by the laser irradiation. The remarkable photo-induced effect was observed for the oxygen 17 NMR measurements. On the other hand, no photo-effect was observed in the associative fluoride exchage reactions of fluoro uranyl(V) complexes with fluoride in the bulk.