Concerted Reactions of Organic Ligands on Transition Metals
The development of the Woodward-Hoffman Rules1 has provided a basis for the understanding of concerted reactions occurring in purely organic systems. Within the framework of this theory concerted reactions may be classified into two groups i.e. “allowed” and “forbidden” processes; and associated with the latter group there is an added energy barrier in the reaction coordinate of the process which generally renders these processes to be of such a high energy that alternative non concerted processes of lower energy are favored if reaction occurs at all. However, when such “forbidden” reactions are conducted with the organic species simultaneously coordinated to a transition metal then it appears that the concerted reaction may then become “allowed”. Theoretical arguments, based on the correlation or orbital symmetries of the reactants and products, have been developed to substantiate the idea of the changeover of the process from “forbidden” to “allowed”;2 these will not be reproduced here, but rather I shall concentrate on the experimental results of three separate reactions which illustrate the phenomenon.
KeywordsMaleic Anhydride Oxidative Addition Iron Carbonyl Acetylene Dicarboxylic Diels Alder
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- 1.R. B. Woodward and R. Hoffman, 1970, “The Conservation of Orbital Symmetry”, Academic Press, New York, N. Y.Google Scholar
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- 5.Submitted for publication.Google Scholar
- 7.Submitted for publication.Google Scholar