Niobium V iodide

The niobium(V) and tantalum (V) iodides were prepared by the method reported by Corbett and Seabaugh for niobium(V) iodide (3). 

Excess pyridine was distilled from the flask, and the resulting product was dried under high vacuum at room temperature to a constant weight. The amount of pyridine utilized in the reaction could then be determined by weight difference before and after reaction. Complete analytical results for the crude products obtained with the chlorides and oromides are given in Table II. Because the tantalum(V) and niobium(V) iodides both yielded free iodine in the reaction with pyridine, their products were washed with chloroform, as described later, before analysis. 

Reactions of Tantalum(V) and Niobium(V) Iodides with Pyridine. Both niobium(V) and tantalum(V) iodide were reduced in pyridine. In each case the di-adduct of pyridine with the metal tetraiodide was produced, along with elemental iodine as its pyridine complex. The two reduction products were identified by analysis after washing with chloroform to remove the iodine liberated in the reaction. Further identification of the tantalum product was provided by x-ray diffraction data, which compared favorably to those obtained for samples of the tetraiododi(pyridine)niobium (IV) as shown in Table V. 

Apparently the dissociation is enhanced in pyridine, owing to formation of the stable complexes of both niobium (IV) iodide and elemental iodine. Although some reduction of tantalum (V) iodide also occurred in pyridine, the analytical data suggest that this reaction was not complete, and that some unreduced tantalum (V) iodide remained in the washed product. By comparison with niobium (V) iodide, the smaller extent of reduction of tantalum (V) iodide may be accounted for in terms of the greater stability of the latter toward the dissociation shown in Equation 8. 

Niobium(V) bromide Niobium(V) chloride Niobium(V) fluoride Niobium(V) iodide Niobium nitride Niobium(II) oxide Niobium(IV) oxide Niobium(V) oxide Nitric acid Nitric oxide Nitrogen... 

---