Exchange kinetic

Recent studies of the 180 isotropic exchange of [V 0028]6 and the orthovanadate ion, [V04] 3 , have shown slow kinetic exchange (fy2> minutes to hours) and have proven the identity of discrete decavanadate ions in solution. 

Because of the complex equilibria involved (Figure 18a), transport rates depend on the delicate balance of many factors including complexation properties and lipophilicity of the carrier, the cation and anion being transported, and the nature of the membrane species itself. Importantly, transport rates are not directly proportional to the cation-carrier complex stability but present a maximum as a function of Ks. If the complex stability is too low, insufficient cation will be complexed at the initial interface and, similarly, if the complex stability is too high, insufficient cation will be released at the opposite interface. A compromise between thermodynamics (stability) and kinetics (exchange rates) of complexation is involved. 

Crans, D.C., C.D. Rithner, and L.A. Theisen. 1990. Application of time-resolved 51-V 2-D NMR for quantitation of kinetic exchange pathways between vanadate monomer, dimer, tetramer, and pentamer. J. Am. Chem. Soc. 112 2901-2908. 

We have studied McConnell s kinetic exchange mechanism by dealing with a one-... 

The various stoichiometric reactions of the aryl-methyl-nickel compounds of la and b leading to reductive elimination can be assembled as components to a catalytic cycle in the cross coupling process. Scheme 2 is consistent with the facts in hand, including the products, stoichiometry, kinetics, exchange and scrambling experiments. 

The details of the modified electron-gas (MEG) ionic model method have been fully described by Gordon and Kim (1972). The fundamental assumptions of the method are (1) the total electron density at each point is simply the sum of the free-ion densities, with no rearangements or distortion taking place (2) ion-ion interactions are calculated using Coulomb s law, and the free-electron gas approximation is employed to evaluate the electronic kinetic, exchange, and correlation energies (3) the free ions are described by wave functions of Hartree-Fock accuracy. Note that this method does not iterate to a self-consistent electron density. 

Primary detection of chemical shifts, coupling interaction and constants including multiple structure to verify concentration, constitution, conformation or symmetry of one or mixture of compounds kinetic, exchange or chemical equilibria information can be obtained by recording a series of spectra as a function of time or temperature. 

Quantitation of Kinetic Exchange Pathways Between Vanadate Monomer, Dimer, Tetramer, and Pentamer J. Am. Chem. Soc. 112, 2901 (1990). 

This term represents the kinetic exchange it contributes to the antiferromagnetic part of the exchange coupling constant (it is negative). The Fock matrix element can be further expanded into the set of canonical molecular orbitals as... 

Kinetic exchange (KE) involves the singly excited ionic structures... 

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