Organometallic Chatt-Dewar- Duncanson model

G.J. Kubas, Metal-dihydrogen and sigma-bond coordination the consummate extension of the Dewar-Chatt-Duncanson model for metal-olefin pi bonding . Journal of Organometallic Chemistry, 635, 37 (2001). 

The course of modern organometallic chemistry has been greatly influenced by three simple generalizations the Dewar-Chatt-Duncanson synergic bonding model for metal-olefin complexes (40, 72) Pauling s electroneutrality principle (174), and the 18-electron or inert gas rule (202). In this section the impact of recent theoretical calculations on these important generalizations will be evaluated. 

The crystal structures of Zeise s salt and of two analogous palladium-olefin complexes were published,shortly after the publication of the Chatt-Duncanson paper. They confirmed the structural proposals made by Chatt, but none of these papers cites Dewar,though metal-olefin bonding models were not discussed. Two short reviews on the history of Zeise s salt, (one part of a more general discussion of the history of organometallic chemistry) also only refer to Chatt s contribution, though neither specifically address questions of bonding. 

The Dewar-Chatt-Duncanson (DCD) model describes the formation of two coordinate bonds resulting from the overlap of two metal and two ligand orbitals. In other words, the DCD model of bonding of organometallic complexes is nothing else but a simple model of metal-ligand double multicenter bonding. Now, since two multicenter bonds can be formed in three distinct ways, i.e., they can be U,... 

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