TY - JOUR

T1 - Complexes of the proton and its hydrates with carbamoylphosphine oxide in wet dichloroethane solutions

AU - Stoyanov, Evgenii S.

AU - Smirnov, Igor V.

AU - Fedotov, Martin A.

PY - 2006/8/3

Y1 - 2006/8/3

N2 - To better understand the complex equilibria involved in the UNEX process for acidic solvent extraction of radionuclides, the interaction of a carbamoylphosphine oxide ligand (L) with the proton of hydrated chlorinated cobalt(III)dicarbollide acid, H[Co(C2B9H 8Cl3)2], has been studied in wet 1,2-dichlorethane (DCE) solution using IR and NMR (13C and 31P) spectroscopy. The formation of two groups of complexes has been determined. The first group contains three complexes with 1:1 composition of acid to ligand (Scheme 1). The second group of complexes has 1:2 composition in the equilibrium, shown in Scheme 2. Within each group, the complexes differ in composition only by the number of incorporated water molecules. The equilibria (Schemes 1 and 2) are both very sensitive to the content of self-associated water in solution and are driven by its concentration, which is unsteady and depends on the solution preparation history. The simultaneous presence of both anhydrous (I, II) and hydrated (III, IIIa, IV) proton solvates indicates that the enthalpies of carbamoylphosphine oxide complex formation with H +, H3O+, and H5O2 + are very close to each other.

AB - To better understand the complex equilibria involved in the UNEX process for acidic solvent extraction of radionuclides, the interaction of a carbamoylphosphine oxide ligand (L) with the proton of hydrated chlorinated cobalt(III)dicarbollide acid, H[Co(C2B9H 8Cl3)2], has been studied in wet 1,2-dichlorethane (DCE) solution using IR and NMR (13C and 31P) spectroscopy. The formation of two groups of complexes has been determined. The first group contains three complexes with 1:1 composition of acid to ligand (Scheme 1). The second group of complexes has 1:2 composition in the equilibrium, shown in Scheme 2. Within each group, the complexes differ in composition only by the number of incorporated water molecules. The equilibria (Schemes 1 and 2) are both very sensitive to the content of self-associated water in solution and are driven by its concentration, which is unsteady and depends on the solution preparation history. The simultaneous presence of both anhydrous (I, II) and hydrated (III, IIIa, IV) proton solvates indicates that the enthalpies of carbamoylphosphine oxide complex formation with H +, H3O+, and H5O2 + are very close to each other.

UR - http://www.scopus.com/inward/record.url?scp=33748316549&partnerID=8YFLogxK

U2 - 10.1021/jp0609838

DO - 10.1021/jp0609838

M3 - Article

AN - SCOPUS:33748316549

VL - 110

SP - 9505

EP - 9512

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

IS - 30

ER -