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A two-state reactivity model explains unusual kinetic isotope effect patterns in C-H bond cleavage by nonheme
Eric J Klinker1, Sason Shaik, Hajime Hirao
1Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN 55455, USA.
Abstract:
It's in the bond: The cleavage of C-H bonds by two related oxoiron(IV) complexes shows a range of kinetic isotope effect (KIE) values that exhibit an unusual dependence on the C-H bond strength. Large nonclassical KIEs are observed for bond strengths below 93 kcal mol(-1), while semiclassical values are found above this value (see graph, DHA = 9,10-dihydroanthracene). This nonintuitive behavior can be rationalized by invoking a two-state reactivity model.
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Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Reaction Mechanisms
For instance, the decomposition of ozone appears to follow a mechanism with two steps:

