Ion-induced-dipole interactions

In Table III we compare for several reactions the experimental rate constants with rate constants calculated on the basis of ion-induced dipole interactions only from the relation (4) ... 

The first two terms C/cou and C/poL correspond to the empirical energy of ion-dipole and ion-induced dipole interactions, being given by... 

Ion-induced dipole interaction energies are proportional to the product of the square of the charge and the polarizability a of the atom/group with which the ion interacts, divided by the product of the dielectric constant D and the fourth power of the distance between the dipoles. 

A solvent, in addition to permitting the ionic charges to separate and the electrolyte solution to conduct an electrical current, also solvates the discrete ions, by ion-dipole or ion-induced dipole interactions and by more direct interactions, such as hydrogen bonding to anions or electron-pair donation to cations. Lewis acidity and basicity of the solvents affect the latter. The redox properties of the ions at an electrode depend on their being solvated, and the solvation effects electrode potentials or polarographic half-wave potentials. 

Franck-Condon modified by ion-induced dipole interaction Franck-Condon at ion velocities > I08 cm/sec at v < I08 cm/sec, relative population of upper vibrational states increases monotonically... 

One possible solvent interaction with solute molecules or ion radicals includes nonspecific (nonbonding) solvation and electron donor-acceptor or ion-induced-dipole interactions. To discern these interactions, one can compare such solvents as toluene and -hexane. At temperatures when all these solvents have comparable viscosity, the reaction between 1,2,4,5-tetrafluorobenzene and its anion radical proceeds in different ways (Werst 1993). 

For monopositive ions and the gases Ar, H2, 02, N2, and C02, the second term is between 18 and 60% as large as the first, which corresponds to the ion-induced dipole interaction. For bipositive ions, the contribution of the second term is only 5 to 15% that of the first. Thus, although the ion-quadrupole interaction is not negligible, it is small compared with the total. The pure quadrupole-quadrupole interaction is of course a much smaller contribution. The absolute maximum magnitude of the second term above is about 1300 cal. per mole for any of the above combinations (C02 and Li+) and the minimum value is about 700 cal. per mole (H2 and K+). 

The similarity in the adsorption behavior of krypton on the three kinds of mica surfaces suggests that the adsorption here is primarily due to dispersion forces, with very little contribution from ion-induced dipole forces. The results of Barrer and Stuart (1) for the adsorption of argon on various ion-exchanged forms of faujasite are similar. They found that while calcium, strontium, and lithium faujasite—i.e., the materials containing cations with greater polarizing power—did show heat effects correlatable with ion-induced dipole interactions, no such effects were observed with sodium, potassium, or barium zeolites. With the latter materials, they also concluded that the adsorbed argon possessed appreciable mobility. 

The unexpected gas-phase double-minimum diagram can be best explained as follows As the reactants approach one another, long-range ion-dipole and ion-induced dipole interactions first produce loose ion-molecule association complexes or clusters. This is related to a decrease in enthalpy prior to any chemical barrier produced by orbital overlap between the reactants. For reasons of symmetry, an analogous drop in enthalpy must exist on the product side. Because the neutral reactant and product molecules will, in general, have different dipole moments and polarizabilities, the two minima will also be different. Only in the case of degenerate identity Sn2 reactions (X + CH3—X —> X—CH3 + X ) will the enthalpy of the two minima be equal. 

Here, we report, for the first time, ab initio computations of the six lowest-lying electronic states of Na2" ". These computations utilize the basis set developed to describe the low-lying states of the neutral Nap, molecules (6) and utilize integrals which have been computed previously (, ). The molecular energies computed at the single-configuration self-consistent-field (SC-SCF) level are listed in Table I. These SC-SCF computations should provide relatively reliable potential curves for what are effectively one-electron systems. We do not attempt to describe the electron correlation associated with the core electron motions nor that associated with the polarization of the core electrons by the single valence electron. Thus, while dispersion effects are not well described, the first order ion-induced dipole Interaction and the major electrostatic interactions of the valence electron are probably reasonably well described at the SC-SCF level. Note in Table II, where we list molecular constants for Nap, that the 1 state is bound. Its 1 T. counterpart in the neutral molecule is predicted to be... 

Ion-Induced Dipole Interactions in the Primary Solvation Sheath... 

Considering a mole of ions and four water molecules in contact with an ion, the heat of ion-induced dipole interactions is... 

If the electric field is caused by an ion, then E = qi/R y where q is the ionic change, i is the unit vector along the ion-molecule direction, and R the ion-molecule distance, which is the E =-l/2aq /R for this ion-induced dipole interaction. The correspondingformulafor dli-pole-induced dipole interaction between two dipolar molecules is... 

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