Water/ethanol complexation induced solubility variation of hexaquocobalt(II) bis (p-toluenesulfonate) and hexaquonickel(II) bis (p-toluenesulfonate)

Water/ethanol complexation inducing solubility variation of transition-metal p-toluenesulfonates (tosylates) was investigated. The solubilities of hexaquocobalt(II) bis (p-toluenesulfonate) [Co(OTs)(2)center dot 6H(2)O] and hexaquonickel(II) bis (p-toluenesulfonate) [Ni(OTs)(2)center dot 6H(2)O] in water/ethanol mixtures were measured at T= 298.15 K. All the experimental data were well-correlated by the (CNIBS)/Redlich-Kister model. A distinct variation phenomenon of solubility was observed when the mole fraction of ethanol (x(0)) changed from 0.000-1.000. Based on the experimental data, two kinds of possible water/ethanol clusters [(water)(2)-ethanol and water-(ethanol)(3)] were proposed, and five special values of x(0) (x(0,1) x(0,5)) were obtained by a mathematical study of the (CNIBS)/Redlich-Kister model. The interactions of hydrogen bonds between tosylates and water (or ethanol, water/ethanol clusters) were calculated by Materials Studio DMol(3). The formation and change of the above clusters at special values of x(0) were analyzed, based on which, the variation of solubility induced by water/ethanol complexation was investigated. (C) 2016 Elsevier B.V. All rights reserved.