Phosphine oxide complexes of protactinium, niobium, and tantalum pentachlorides

Abstract

Phosphine oxide complexes of protactinium, niobium, and tantalum pentachloride, MCl₅,R₃PO [M = Pa, Nb, and Ta; R = C₆H₅ and N(CH₃)₂] and MCl₅,R₂R′PO (M = Pa and Ta; R = C₆H₅; R′= C₆H₅·CH₂), have been prepared in anhydrous methyl cyanide and methylene dichloride. Niobium(V), but not protactinium(V), forms an oxychloro-complex, NbOCl₃,2(C₆H₅)₃PO, in the presence of an excess of triphenylphosphine oxide. Some chemical properties, infrared spectra, and X-ray powder diffraction data are reported.