Thermal reactivity electronic structure

A wide variety of instrumental techniques, including X-ray diffraction, thermal analysis, electron microscopy, MAS-NMR and infrared spectroscopy, have been employed at different levels of complexity to investigate the effects of mechanochemical treatment on kaolin. Unfortunately, vibrational spectroscopy has only been used at a superficial level in the study of milled kaolin despite the considerable contribution that it has made to the understanding of the structure and reactivity of kaolin itself. 

Dollimore [5] has discussed some aspects of the influence of the central atom on the thermal stabilities of solid coordination compounds. The most fully characterized compounds are those of Co, Cr and Pt. Central atoms of relatively small radius but high oxidation number coordinate most effectively. The possible influences of melting and dependences upon reaction conditions increase the difficulties of identification of the factors which control reactivity. Stabilities are influenced [5] by the electronic structure of the coordinated ion, whether this is a normal or a penetration compound. In the latter species, covalent bonding involves 3dHs4p orbitals, whereas in a normal coordination compound the 4s4pMd orbitals... 

Thermal organic reactions are often classified in terms of the molecular and electronic structure of their transition state or reactive intermediate (which is often taken as a model of the transition state). Thus, for instance, one has the Sn2 transition state for concerted bimolecular nucleophilic substitution reactions one has the E2 and Ei transition states in elimination reactions, etc. Given the transient nature of the transition states, the use of quantum chemical methodologies is essential for the determination of their detailed geometrical and electronic structure. Furthermore, the computation of the associated transition vectors provides information on the reactive mode... 

The acid-catalysed and thermally induced rearrangements of cyclohexadienones have been surveyed recently, and an attempt was made to reduce the plethora of apparent sigmatropic shifts to a smaller number of independent reactions in these blocked aromatic molecules . The electronic structure and reactivity of cyclohexa-dienone carbenes has also received coverage in a review. 

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