Hydride fluxionality in transition metal complexes: An approach to the understanding of mechanistic features and structural diversities

The mechanisms of intramolecular dynamics in transition metal hydride complexes are surveyed in this review. The NMR data for a number of fluxional hydrides are interpreted in terms of principal and secondary topological changes of the coordinated ligands. The principal ligand motions can be further categorized as being of migratory (M) and replacement (R) type. Discussion of these ligand motions is followed by analysis of more complex rearrangements of hydride systems, in which both types are operative in multiple exchange processes. The attempted systematic approach appears to be a useful general mechanistic concept for the understanding of the fluxional behavior of hydride complexes.