AGGREGATION BEHAVIOR OF COBALT(II), NICKEL(II), AND COPPER(II) BIS(2-ETHYLHEXYL) PHOSPHATE COMPLEXES IN n-HEPTANE

Abstract

ABSTRACT The solution behavior of divalent transition metal-bis(2-ethylhexyl) phosphate (M(DEHP)2, M = cobalt, nickel or copper) complexes in n-heptane have been investigated by vapor pressure osmometry, viscometry and dynamic light scattering. Co(DEHP)2 complexes tend to form large macromolecular species with a mean aggregation number Nagg as large as 225, and the size of the macromolecular species decreases with increasing Co(DEHP)2 concentration. In contrast, Cu(DEHP)2 complexes tend to form small macromolecular species Nagg = 4-8 which increase in size with increasing Cu(DEHP)2 concentration. On the other hand, Ni(DEHP)2 complexes (and Ni(DEHP)2-2H2O complexes when the molar ratio of H2O