SANS STUDY OF DIALKYLSUBSTITUTED DIPHOSPHONIC ACIDS AND THEIR COMPLEXES WITH CA, FE, LA, TH AND U IN TOLUENE

The aggregation of di(2ethylhexyl) methane-, ethane- and butanediphosp honic acids and their complexes with various metal cations at differen t concentrations in toluene have been studied in detail using small an gle neutron scattering. The diphosphonic acids are being employed as n ovel solvent extraction reagents in the Chemistry Division of ANL. The se compounds exhibit extraordinarily strong affinity for actinide ions and for Fe(III). The growth of large metal-diphosphonate aggregates d epends on the metal species, metal to extractant ratio, and the length of the carbon bridge between the two acid groups. Fe(III) complexes w ith the methane and butane (but not the ethane) bridged diphosphonic a cid aggregate to form large polymeric rods at high metal to extractant ratios. Actinide ions likewise give large aggregates with di(2ethylhe xyl) methanediphosphonic acid. Ca2+ and La3+ show only the usual forma tion of small 'monomeric' chelates. Published by Elsevier Science B.V.