EXTRACTION OF VO(IV) AND FE(II) WITH HEPTANOIC ACID IN THE PRESENCE OF 1,10-PHENANTHROLINE AND 2,2'-DIPYRIDYL

The extraction equilibria in the system VOSO4-(NH4)(2)SO4-1,10-phenant hroline-heptanoic acid-benzene have been interpreted in terms of the d inuclear complex [VO(phen)A(2)](2) formation in the organic phase. In the systems 2)SO4-2,2'-dipyridyl/1,10-phenanthroline-heptanoic acid-be nzene, the mononuclear complexes [Fe(dipy)(3)A(2)(HA)(12)], [Fe(dipy)( 3)A(2)(HA)(11)] and [Fe(phen)(3)A(2)(HA)(11)] occur in the organic pha se. Surprisingly, the complexes of Fe(II) formed in the presence of 2, 2'-dipyridyl are not stable in the organic phase. The electronic absor ption spectra of the organic phases containing such complexes show tha t 2,2'-dipyridyl loses its ability to prevent Fe(II) oxidation in cont act with air.