Density functional theory reveals multiple pathways for intramolecular hydride transfer in the cyclopentadienyl and indenyl species (η5-C5H5)Fe(CO)3H and (η5-C9H7)Fe(CO)3H. The ability of the indenyl ligand to undergo facile η5- to η3-'ring slippage' stabilises the isomer where the hydride is bonded directly to the metal, which opens up a low-energy pathway for hydride transfer from CO to metal. © 2008 Elsevier B.V. All rights reserved.
