ANALYTICAL AND SPECTROSCOPIC STUDY OF INDIUM EXTRACTION WITH 1,10-BIS(1-PHENYL-3-METHYL-5-HYDROXY-4-PYRAZOLYL)-1,10-DECANEDIONE AND ITS MIXTURES WITH TRI-N-OCTYLPHOSPHINE OXIDE

Complex organic phases are obtained by extraction of indium from 1 M perchlorate media with chloroform solutions of 1,10-bis(1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl)-1,10-decanedione, "HL-8-LH". PMR and analytical data show that, at low pH and for low extractant concentrations, four extracted species are present: In(L-8-L) (L-8-LH), In2(L-8-L)3, In(L-8-LH)3 and In2(L-8-L)2 (L-8-LH)2. The corresponding extraction constants have been estimated, resp. 0.0 < log K12 < 1.0; 1.2 < log K23 < 2.2; 1.0 < log K13 < 2.2 and 0 < log K24 < 3. At highest pH's, polymeric species are formed. The extractible complex In2(L-8-L)3 has been synthesized. It contains two "(L-8-L)In" moieties where L-8-L2- acts as a bis-chelatant folded on the indium atom, linked by a L-8-L2- bridge. This complex slowly rearranges in chloroform solutions to form polymeric species. A weak synergy is observed by adding tri-n-octylphosphine oxide, "TOPO", to the extraction solvent. The organic extraction phase mainly contains In2(L-8-L)3 (TOPO)2. The corresponding extraction constant is log K232 = 6.6 +/- 0.2. P-31-NMR shows that this complex is not formed by TOPO addition in the organic phase, contrary to the usual description of the synergistic effect.