ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Study of some complex compounds of zirconium, hafnium, niobium, and tantalum

I. A. Sheka

Academy of Sciences U.S.S.R., Kiev.

Abstract: Phase and cryoscopic changes in the systems Zr^-, Hf^-, Nb^-, and TaCln-POCl₃ were studied to det. the compn. of compds. and their relative stability in fusions and solns. The diagrams of fusion of ZrCl₄ and HfCl₄ with POCl₃ show the formation of complexes ZrCl₄.2POCl₃, ZrCl₄.POCl₃, HfCl₄.2POCl₃, and HfCl₄.POCl₃. By cryoscopic study of these systems in PhNO₂ it was detd. that both type of complexes are present at the same time. The instability const. of ZrCl₄.2POCl₃ is slightly lower than that of the corresponding Hf compd. Fusion and liquid-vapor phase equil. diagrams of the systems NbCl₅ or TaCl₅ and POCl₃ show the formation of complexes NbCl₅.POCl₃ and TaCl₅.POCl₃. Cryoscopic detns. in benzene show that these compds. exist in the soln. as monomers. From the liquid-vapor phase equil. in the systems contg. NbCl₅, TaCl₅, ZrCl₄, or HfCl₄ with POCl₃ it was detd. that the distn. products are azeotropic mixts. The ability to form complexes and the thermal stability of complexes with POCl₃ increases with a higher at. no. of the element and with increase in its ionic radius. The alcoholysis of ZrCl₄ and HfCl₄ with MeOH and the formation of mono- and disubstituted methoxychlorides are described. In PhNO₂, mol. complexes of ZrCl₄ and HfCl₄ with 2 mols. of MeOH are formed. New data on the compn. of complex hydroxozirconate and hydroxohafnate ions are given.

Full paper in Portable Document Format: 1311a656.pdf (in Russian)

Chemical Papers 13 (11) 656–668 (1959)