Acceleration of Sm(III) → Sm(II) reduction under the combined action of the chemical reductant diisobutylaluminum hydride and UV irradiation

Abstract

It was found a significant acceleration of the reduction of Sm(III) during the joint action of the chemical reductant iBu2AlH (Bu = C4H9) and UV irradiation on the SmCl3·(THF)x–iBu2AlH complex. This complex is formed in interaction of iBu2AlH with the SmCl3·6H2O suspension in THF. The reduction process of Sm(III) is effectively controlled due to change in time of the photoluminescence and absorption spectra of the reaction solution. The complexometric method and elemental analyzes, as well as the UV–visible and IR spectroscopy were used for identification of the chemical composition of the SmCl2·(THF)2 complex, which was isolated from the reaction solution of a more bulky complex SmCl2·(THF)x–iBu2AlH. This bulky complex, like other known lanthanide Ziegler-Natta catalysts, is perspective as a catalyst for a number of organic reactions. Besides, it is advanced as a very efficient enhancer of chemiluminescent redox reactions of organoaluminum compounds. The mechanism of the Sm(III) ion reduction is proposed, which includes photolysis of the Al–H bond in the iBu2AlH hydride with the formation of atomic hydrogen (H). The latter, attacking complex SmCl3·(THF)x–iBu2AlH, reduces of Sm(III) to Sm(II).