Orientational Intermolecular Potentials in Ionic Hydration Shells from Micro‐dynamic Data

Tutsch

Versmold

1971

Self Cite

Experimental results for the nuclear magnetic relaxation rate of Li7 in H2O and D2O solutions of LiCl, LiBr, and LiI are reported. The relaxation contribution due to magnetic dipole‐dipole interaction is separated, the rotational correlation time of the vector connecting the cation with the 1st hydration water is determined and the latter time is compared with the correlation time of the H – H vector in H2O of the 1st hydration sphere. Both times are not equal which indicates that the water molecules rotates about the Li – O axis. The quadrupolar contribution to the relaxation rate of Li7 is interpreted in terms of a break‐down of cubic symmetry in the hydration sphere as the salt concentration increases. Self‐diffusion data of Li+ in LiCl, LiBr, and LiI solutions are as well reported and a structural interpretation of the concentration dependence is given. Proton relaxation rates of AlCl3 solutions containing 100% H2O and of those which contain only a very small amount of HDO in D2O are given. The evaluation yields the result that the correlation times of the two vectors in the hydration sphere as described above are equal for Al3+. Some structural consequences are described, proton relaxation rates in Ga3+ solutions, Al27 relaxation rates in AlCl3 solutions, and water self‐diffusion coefficients in AlCl3 solutions are reported.

Molecular Motion and Structure around the Hydrated Ions Li⁺and Al³⁺

Tutsch

Versmold

1971

Self Cite

The Orientation of the Water Molecules in the Hydration Sphere of F⁻ and in the Hydrophobic Hydration Sphere

Rädle

1973

Nuclear magnetic relaxation rates of 19F in aqueous KF solutions and of the proton in aqueous solutions of formic acid, HCOOD, of pro‐pionic acid, CHD2CD2COOD, and of methanol, CHD2OD are reported. The solvent water is 16OD2 to which suitable amounts of 17OD2 or 16OH2 are added. From the intermolecular relaxation rate of the solute nucleus (19F or H), caused by the dipole‐dipole interaction with the magnetic nuclei in the solvent, the orientation of the water molecules in the hydration sphere of the solute particle has been derived. Our results regarding the angle of the electric dipole moment of the H2O molecule relative to a radial reference axis are: βo = 50° for F−. βo = 96° for formic acid, βo = 107.5° for propionic acid and βo = 102.5° for methanol.

Information on the Orientation Dependent Molecular Distribution Function from Nuclear Magnetic Relaxation Data

1976

Self Cite

A general relation is given which allows the experimental determination of as many parameters of the orientation dependent molecular distribution function as intermolecular nuclear magnetic relaxation rates can be measured involving different interaction partners in the molecular pair. Then the construction of simple model molecular pair distribution functions from model atomic pair distribution functions is described. Finally, a method is reported which offers a qualitative determination of the configurational range involved in a given thermodynamic stability constant.Es wird eine allgemeine Beziehung angegeben, welche die experimentelle Bestimmung von so vielen Parametern einer orientierungsabhangigen molekularen Paarverteilungsfunktion gestattet, wie intermolekulare kernmagnetische Relaxationsraten gemessen werden konnen, die auf verschiedene Wechselwirkungspartner in dem Molekiilpaar zuriickgehen. Sodann wird die Konstruktion einer einfachen Modell-Molekiilverteilungsfunktion aus Modell-Atomverteilungsfunktionen durchgefiihrt. SchlieBlich wird iiber eine Methode berichtet, mit der es auf qualitativer Basis moglich ist, Auskiinfte uber den Konfigurationsbereich zu erhalten, den eine gegebene thermodynamische Stabilitatskonstante beinhaltet.