Overview of Sigma Complexes

Orbital interactions in a Chalt-Dewar-Duncanson bonding model applied to complexes. 

Considering this result and proposals of alkane complexes in matrix isolation studies, both before and after Kubas s discovery, Bergman explained results of H-D exchange between the hydride and cyclohexyl group of the complex in Equation 2.20 and kinetic isotope effects for reductive elimination by invoking an intermediate in which the alkane is bound to the transition metal through a C-H bond, This proposal of an alkane complex is now fully accepted, although the precise structure of such a complex in solution is unknown. 

Comparison of electrons involved in a a-complex and in hydrogen bonding. 

A complex involving hydrogen bonding from an N-H proton to the axial position of a square planar platinum. 

Examples of hydrogen bonding from a protic group to a metal hydride. 

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