Hydride shuttle process

The mechanism of this unique H-D exchange is of considerable importance. The usual mechanism proposed for H-D exchange in d-block transition metals involves a series of reductive-elimination, oxidative-addition cycles. The prerequisite in this type of process is the ability of the metal atom to shuttle between two readily available oxidation states. This type of mechanism could be invoked to explain the exchange reaction in the uranium hydride since uranium (VI) is a well-known oxidation state. The observation that the thorium hydride also undergoes exchange at a comparable rate shows that such a process is not viable as thorium (VI) is unknown. Scheme III outlines an... 

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