NMR STUDY OF LANTHANIDE(III) NITRATE-CMPO EXTRACTION SYSTEM (II)MOLECULAR MOVEMENT OF CMPO AND La(III)(NO3)3-CMPO COMPLEX AND LIGAND-EXCHANGE REACTION FOR Eu(III)-CMPO AND Gd(III)-CMPO SYSTEMS

Abstract

ABSTRACT NMR( Nuclear Magnetic Resonance ) measurements were car ried out to study the molecular movement of CMPO and La(III)(NO3) 3− CMPO complex and the ligand-exchange reaction for Eu(III) and Gd(III)-CMPO systems. From the 13C relaxation time measurement of La(NO3) 3 3CMPO it was found that the T1 value for the isobutyl CH and CH2 carbons and the carbonyl carbon became considerably shorter on complexation, indicating that the carbonyl group participates in the bonding between CMPO and La3+ ion as well as the phosphoryl group. The numbers of CMPO molecules coordinated to Eu3+ and Gd3+ ions in CDCl3 solution were estimated to be 3 and 2, respectively, in the presence of excess CMPO. The activation parameters for the ligand-exchange reaction were evaluated to be ΔH* = 37.8±1.9[kJ/mol],ΔS* = -59.9±6.5[J/molk• K] and ΔH* = 41.3±1.6[kJ/mol], ΔS* = -44.1±5.3[J/mol-K] for Eu(III)-CMPO and Gd(III)-CMPO systems, respectively. The independence of the exchange rate constants on the concentration of CMPO indicates...