Some New Actinide Tetrahalide-NN Dimethylacetamide Complexes

Abstract

Protactinium tetrachloride reacts with NN dimethyl-acetamide (DMA) in anhydrous, oxygen-free carbon tetrachloride to form PaCl4 · 3 DMA. This can be degraded to PaCl4 · 2.5 DMA but this is a different crystal modification to that previously reported for the MCl4 · 2.5 DMA (M = U, Np, Pu) complexes; three different crystal modifications of the complexes of this type have now been obtained. Actinide tetrabromides form complexes of the type MBr4 · 5 DMA (M = Th, Pa and U) as well as those of the type MBr4 · 2.5 DMA (M = Pa and U only). Reactions in acetone result in the formation of adducts of the type MBr4 · 4 DMA • CH3COCH3 (M = Th and U only). The preparation and interconversion of the various types of complex are discussed and some chemical properties, infrared spectra, NMR spectra and X-ray powder diffraction results are reported.