Niobium bromide, anhydrous

Weight gain data and oxidation-reduction titers (Table II) for the niobium (V) chloride and bromide reaction products both indicated the reduction of niobium (V) to niobium (IV). The niobium (IV) adducts were separated by washing the crude reaction mixtures with anhydrous acetonitrile. This solvent removed the various organic products of the initial reaction plus any unreduced niobium compounds. Analysis of the washed products gave ratios of Nb X py of 1 4 2 and agreed with analyses for samples of NbCl py2 and NbBr4 py2 which... 

Samples of both the bromide and chloride crude reaction mixtures were extracted with anhydrous chloroform to obtain a chloroform-soluble residue. Chloroform extraction was chosen here, because the niobium (IV) adducts appeared to be substantially insoluble in this solvent. Samples of the soluble residue were dissolved in anhydrous chloroform for infrared analysis. The resulting absorption spectra were then compared to those obtained in the same way for known samples of pyridinium chloride and bromide (Table VI). 

Niobium(V) bromide (2 g.) is dissolved in anhydrous acetonitrile (10 ml.) and excess solvent removed in vacuo at room temperature to leave the dark-red solid complex (yield 100%). 

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