Exchange dynamic

The solvated sulfenamides [Li2( BuNSC6H4Me-4)2(THF)n] (n = 2,4) have dimeric structures with a central Li2N2 ring. The coordination mode is determined by the extent of solvation of the Li" ions monosolvation allows for rj -N,S coordination whereas disolvation restricts the coordination mode to // -M Variable temperature NMR studies indicated that a dynamic exchange between these two structural types occurs in THF solution (Scheme 10.10). The dihapto coordination mode is observed exclusively in transition-metal complexes and the... 

Molecules adsorbed at interfaces are in constant motion, both from the point of view of their orientation and of the dynamic exchange with the bulk solution. The distribution of orientation angle is characterized by the parameter D, see Eq. (13), or the angle of orientation Q. Complete randomness for the angle 0, the angle of rotation around the principal... 

Ion-exchange chromatography (lEC) is used mainly for the separation of ions and easily ionized substances (e.g., substances that form ions by pH manipulation or complexation) in which one of the principal contributions to retention is the electrostatic attraction between mobile phase ions, both sa le and eluent, for immobilized ion centers of opposite charge in the stationary phase. The sample ions are separated based on differences in their relative affinity for the stationary phase ion centers compared to that of the mobile phase counterions in a dynamic exchange system, in which sample ions and eluent ions interact with multiple stationary phase ion centers as they pass through the column. Ion-... 

During a study of the physicochemical properties of some aminoglycoside antibiotics Kuzyaeval- - determined the static and dynamic exchange capacities of neomycin on the cation exchange resin KB-4P-2(a phenoxyacetic ac. d-f ormaldehyde resin) using the resin in the Na form. 

For most of the situations encountered in solvent extraction the gas phase above the two liquid phases is mainly air and the partial (vapor) pressures of the liquids present are low, so that the system is at atmospheric pressure. Under such conditions, the gas phase is practically ideal, and the vapor pressures represent the activities of the corresponding substances in the gas phase (also called their fugacities). Equilibrium between two or more phases means that there is no net transfer of material between them, although there still is a dynamic exchange (cf. Chapter 3). This state is achieved when the chemical potential x as... 

Other modifications to the reaction conditions of the Brust-Schiffrin method, such as a reduction temperature of — 78 °C and the use of a hyperexcess of hexanethiol, results in an Au38(thiolate)24, based on observations, LDI-TOF mass spectrometry, TGA analysis and elemental analysis [69]. The influence of preparation temperature on the size and monodispersity of dodecylthiol monolayer protected gold clusters has also been reported. Both and SAXS measurements show that higher temperatures increase polydispersity. This modification of poly-dispersity may be related to the existence of a dynamic exchange of thiols at the particle surface with thiols in the solvent [70]. 

Recent examples of this kind of methodology can be found, for example, in the work of Rebek et al. [10] The catalyst used is a cavitand armed with a Zn salen-type complex (Figure 1.2). The cavitand adopts a vase-like conformation that is stabilized by a seam of hydrogen bonds provided by the six secondary amides. The structure of the catalyst permits a slow dynamic exchange between free and bound guest (reactant) on the H NMR time-scale that is controlled by the folding and unfolding of the cavitand. 

In the case of chemical or dynamical exchange processes, cross peaks originating... 

Spin-.spin connectivities based on dynamic exchange including the parameters necessary to quantify these processes (k, AG , AH", AS ). 

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