Metal-hydrogen interactions

The y-agostic interaction is such that the electron pair in the C, -He bond of the alkyl substituent at the metal is partly donated to the electron-poor metal this may play an important role in making more simple the insertion of a coordinated olefin into the metal-alkyl bond. This hypothesis has been tested in some instances [346-350], showing metal-hydrogen interaction via an oc-agostic bond. 

Here, it is important to note that not only the metal-hydrogen interaction but also the metal-metal interaction is important in understanding the hydriding property of metals. This is also the case for hydrogen storage alloys, as explained later. 

Fig.5. Schematic illustration of metal-hydrogen interactions in (a)LaH and (b) LaNi H ...

Yoshida H, Okuno K, Naruse Y, Kashiwai T. Metallurgical considerations on Pd, Pd-alloys and their metal-hydrogen interactions. Fusion Technol 1985 8 2388-94. 

The hydrogen vibrational spectra provide direct information on the strength of the metal-hydrogen interaction and therefore on the hydrogen potential. Accurate knowledge of the hydrogen potential is of fundamental importance for the understanding of many properties of metal-hydro-gen systems, e.g., thermodynamic behavior (chemical potential), diffu-... 

The anomalous stretching frequency has been attributed to interaction of the endo-C—Hoc with the metal its absence in the exo-substituted phenylcyclopentadiene cobalt complex (Figure 19) has been explained by an increased bending-away of the methylene carbon from the metal atom which makes the enrfo-hydrogen-metal distance too large for appreciable metal-hydrogen interaction [56]. 

In the context of weak metal-hydrogen interactions, the unusual infrared spectra of metal cyclopentadiene complexes should also be remembered (see Chapter 7). 

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