Swain kinetic complexity

The disintegration of a substance in a first-order manner. 2. A breakdown of the Swain-Schaad relationship in kinetic isotope effect studies usually as a consequence of tunneling or kinetic complexity. 

The primary exponential relationship comes from a comparison of the primary (kH/kx)2 H primary (kD/kx)2oD isotope effects. It has been shown that primary exponents are not susceptible to large Swain-Schaad deviations, even in the event of fairly extensive tunneling [59] furthermore, primary exponents are not susceptible to large RGM deviations [52], and consequently, the composite exponent RS should remain close to 3.3 in the absence of kinetic complexity. This is a useful control, as the magnitude of the primary exponent is reduced when chemistry is only partially rate limiting (i.e., it can be use to establish that H-transfer has been kinetically isolated) [60]. 

Hirschi, j., Singleton, D. A. (2005) The normal range for secondary Swain-Schaad exponents without tunneling or kinetic complexity, J. Am. Chem. Soc. 127, 3294-3295. 

A completely empirical LFER can also be constructed with recourse only to kinetic data. This has been the case in the setting up of a scale of nucleophilic power for ligands substituting in square-planar complexes based on the Swain-Scott approach. The second-order rate constants Ay for reactions in MeOH of nucleophiles Y with tra 5-Pt(py)2Cl2, chosen as the standard substrate... 

Almost simultaneously, in 1963, another research group reported on the reaction kinetics of methylmagnesium species with benzophenone [40] (a preliminary communication of this work had appeared in 1961). These authors came to conclusions that differed considerably from the previous ones. Very explicitly they expressed as their opinion that ... the concept of the Grignard reaction with a ketone proceeding via a stable complex of the type described by Swain [see Ref. 38] is not supported by the published evidence [41] nor by the results of the present investigation. ... 

There is evidence that interactions between Co " and DOM are significant in humic-rich environments such as pore waters (Elderfield and Hepworth, 1975 Nissenbaum and Swaine, 1976) and fresh waters (Barsdate and Mat-son, 1967 Means et al., 1977). Mantoura (1976) used a multi-metal, multiligand equilibrium speciation model and calculated that <10% of Co is bound to lake-water fulvic acid. The kinetically non-labile nature of Co complexes with humic compounds (MacCarthy and O Cinneide, 1974) has been used as a basis for a polarographic determination of metal complexa-tion capacity of natural waters (Hanck and Dillard, 1977). 

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