Some bromo-complexes of quinquevalent protactinium, niobium, and tantalum

Abstract

Hexabromo-protactinates(V), -niobates(V), and -tantalates(V), RM^vBr₆(R = NMe₄, NEt₄, and Ph₃BuP; M^v= Pa, Nb, and Ta), have been prepared from methyl cyanide solutions of the appropriate pentabromide. Niobium(V) and tantalum(V), but not protactinium(V), form complexes of the type NMe₄M^vBr₆,CCl₄(M^v= Nb and Ta) on the addition of excess of carbon tetrachloride to the tetramethylammonium hexabromo-complex dissolved in methyl cyanide. Some chemical properties, infrared spectra, and X-ray powder diffraction are reported for these complexes and for the methyl cyanide complexes PaBr₅,3CH₃CN and M^vBr₅,CH₃CN (M^v= Nb and Ta).