Reactivity studies, transition metal

Thus the reactivity of transition metal-carbene complexes, that is, whether they behave as electrophiles or nucleophiles, is well explained on the basis of the frontier orbital theory. Studies of carbene complexes of ruthenium and osmium, by providing examples with the metal in either of two oxidation states [Ru(II), Os(II) Ru(0), Os(O)], help clarify this picture, and further illustrations of this will be found in the following sections. 

In 2003, we presented two reviews concerning spin-forbidden reactions in transition metal chemistry (10,16). A number of other reviews in 2004 addressed closely related topics (90,91). However, since then, we are not aware of any review on this topic. We, therefore, present a short discussion of a number of recent studies of reactivity in transition metal chemistry for processes involving changes in spin-state. The aim here is not to be exhaustive, as there are now quite a lot of studies of transition metal chemistry that address the topic of spin-state changes. Instead, this is an attempt to give a flavor of the types of question that are being addressed now and the techniques used to investigate them. 

Studies of the reactivity of transition metal cyclopropenylium complexes are negligible. A single example on the acid hydrolysis of the hexachloroantimonate palladium dimer complex [(i-Pr2N)2C3(PdCl)]2-2SbCl6, and its demetallation using SbCl5, is outlined in equation 293. 

Computational Studies of Reactivity in Transition Metal Chemistry... 

COMPUTATIONAL STUDIES OF REACTIVITY IN TRANSITION METAL CHEMISTRY... 

The stability of the adsorption of a hydrocarbon on the active site prior to C-H bond dissociation apparently strongly depends on the nature of the site and has not yet been unequivocally established. None of the studies on oxidative coupling of methane on non-transition metal oxides reported a stable methane preadsorption.34 Transition metal oxides, however, may reveal different behaviour and there exists already theoretical evidence for stable methane adsorption on transition metal atoms and complexes.35 Also the stability of the so-called encounter complexes has been qualitatively predicted to increase the reactivity of transition metal MO species... 

There is a great range in reactivities of transition metal-alkyls towards SO2. Numerous studies of SO2 insertion reactions have been reported for CpFe(CO)2R complexes, which react rapidly in refluxing sulfur dioxide (—10 °C) to give S-sulfinates,... 

In order to illustrate the complexity of excited states reactivity in transition metal complexes two selected examples are reported in the next section dedicated to the ab initio (CASSCF/MR-CI or MS-CASPT2) study of the photodissociation of M(R)(CO)3(H-DAB) (M=Mn, R=H M=Re, R=H, Ethyl) complexes. Despite the apparent complexity and richness of the electronic spectroscopy, invaluable information regarding the photodissociation dynamics can be obtained on the basis of wave packet propagations on selected 1-Dim or 2-Dim cuts in the PES, restricting the dimensionality to the bonds broken upon visible irradiation (Metal-CO or Metal-R). The importance of the intersystem crossing processes in the photoreactivity of this class of molecules will be illustrated by the theoretical study of the rhenium compound. 

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