Olefins theoretical studies

Deubel, D. V., Frenking, G., 1999, Are there Metal Oxides that Prefer a [2+2] Addition over a [3+2] Addition to Olefins Theoretical Study of the Reaction Mechanism of LRe03 Addition (L = O", Cl, Cp) to Ethylene , 7. Am. 

Sakaki S (2005) Theoretical Studies of C-H s-Bond Activation and Related by Transition-Metal Complexes. 12 31-78 Satoh T, see Miura M (2005) 14 1-20 Satoh T, see Miura M (2005) 14 55-84 Savoia D (2005) Progress in the Asymmetric Synthesis of 1,2-Diamines from Azomethine Compounds. 15 1-58 Schmalz HG, Gotov B, Bbttcher A (2004) Natural Product Synthesis. 7 157-180 Schmidt B, Hermanns J (2004) Olefin Metathesis Directed to Organic Synthesis Principles and Applications. 13 223-267... 

Reflecting similar developments throughout organic chemistry there has been a notable increase this year in the number of theoretical studies of ylides and their reactions. Methods of olefin synthesis involving phosphine oxides are discussed in Chapter 3. 

Theoretical studies of catalytic alkane-dehydrogenation reactions by [(PCP )IrH2], PCP rf-C6H3(CH2P112)2-l, 3 and [cpIr(PH3)(H)]+, suggest that they proceed through similar steps in both cases namely (i) alkane oxidation, (ii) dihydride reductive elimination, (iii) /3-II transfer from alkyl ligand to metal, (iv) elimination of olefin.402 The calculated barriers to steps (i), (ii), and (iv) are more balanced for the PCP system than for cp(PH3). 

Spectroscopic Studies on Carbenium Ions derived from Aromatic Olefins V. Experimental and Theoretical Studies of the Cations derived from Acenaphthylene, S.D. Pask and P.H. Plesch, European Polymer Journal, 1982,18, 939-943. 

Theoretical studies have been carried out on all the late transition metal catalysts la [10-13], lb [14] and lc [15] in Figure 1. It is not the objective here to review all the computational results. We shall instead describe the general mechanistic insight that has been gained from the theoretical studies with the main emphasis on Brookhart s bis-imine catalysts. The experimental work on late transition metal olefin polymerization catalysts has been reviewed recently by Ittel [16] et al. 

The three theoretical studies presented above give somehow different conclusions regarding the detailed reaction mechanisms. The difference is apparently related to the different models used and different theoretical approaches employed in the calculations. In any case, the emerging overall picture is that the reaction mechanism of olefin hydroborations must be complicated. We would like to see more experimental work done in the future so that the theoretical results can be tested. In particular, it would be nice to evaluate experimentally the utility of the suggestion made by Ziegler and co-workers in the choice of the phosphine ligands in order to produce more pure product. 

In this chapter, theoretical studies on various transition metal catalyzed boration reactions have been summarized. The hydroboration of olefins catalyzed by the Wilkinson catalyst was studied most. The oxidative addition of borane to the Rh metal center is commonly believed to be the first step followed by the coordination of olefin. The extensive calculations on the experimentally proposed associative and dissociative reaction pathways do not yield a definitive conclusion on which pathway is preferred. Clearly, the reaction mechanism is a complicated one. It is believed that the properties of the substrate and the nature of ligands in the catalyst together with temperature and solvent affect the reaction pathways significantly. Early transition metal catalyzed hydroboration is believed to involve a G-bond metathesis process because of the difficulty in having an oxidative addition reaction due to less available metal d electrons. 

These complexes are effective catalysts in epoxidation reactions with H2O2 and alkyl hydroperoxides. Several detailed mechanistic studies have been carried out in particular, it has been shown that, when the alkyl chain contains a double bond, no autoepoxidation is observed both in the solid state and in solution. Nevertheless, if f-BuOOH is added, the epoxidation of the olefinic moiety immediately takes place. Therefore, it has been suggested that these complexes are not the active species in the oxygen transfer step to the substrate, but they behave as catalysts for the primary peroxidic oxidant. On the basis of kinetic, spectroscopic and theoretical studies, the authors provided a mechanism, whose key steps are sketched in Scheme 12. In this context a major role appears to be played by the fluxionality of the particular ligands used . ... 

Metal cluster complexes containing vinylidene ligands have been considered as models of species present when olefins or alkynes are chemisorbed on metal surfaces (114). Vinylidene has been detected in reactions of ethylene or acetylene with Fe(100), Ni( 111), and Pt(l 11) surfaces (115), and was shown to be an intermediate by theoretical studies on a manganese surface (116). The facile cleavage of C-H bonds which occurs in these systems, together with hydrogen addition or abstraction, also occurs on metal clusters. Typical of the reactions considered is the hydrogen transfer reaction... 

Intramolecular coordination is apparently responsible for most examples of regioselective Wacker oxidations of internal olefins, but electronic effects are also operating [28], specifically in acceptor-substituted olefins. Steric effects are currently not well explored [8], Recent theoretical studies on the mechanism of the Wacker and related reactions are available elsewhere [29, 30],... 

The role of SnCLt as catalyst in [2+2] cycloaddition reactions of olefines which are activated by selenophenyl and silyl groups in the 1,1 position with vinyl ketones has been examined in a combined experimental/theoretical study by Yamazaki et al.166. Calculations at the HF level showed that the formation of a chelate complex where the selenium atom of the olefin and the oxygen atom of the keto group are bonded as ligands to the... 

Koga, N., Yoshida, T. and Morokuma, K, Theoretical Studies on Olefin Polymerisation using Group IV Metallocene Catalysts , in Ziegler Catalysts, Springer-Verlag, Berlin, 1995, pp. 275-289. 

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