Complexing of niobium ions with benzoylphenylhydroxylamine and o-nitrophenylfluorone in hydrochloric acid medium

Conditions and mechanism of niobium (5) complexing with benzoylphenylhydroxylamine (BPHA) and o-nitrophenylfluorone in hydrochloric acid medium have been studied. A different ligand complexes is extracted from the solution by chloroform, the maximum yield is achieved at 3.8 M concentration of HCl. Concentrational effect of LiCl and ethanol on the different ligand complex yield is considered. It is pointed out, that a 2h hold-up of chloroform extractants, prepared from the solutions with the HCl concentration in the 1.6-2.2 M range causes bathochromic shift of the light absorption maximum from 518 to 540 nm as well as an intensity increase at 540 nm. The structure of the different ligand molecule is suggested