DOI: 10.1002/chem.202401536   (OpenAccess)

Striking Borane Planarization in the Thermal Rearrangement (η5-C5H5)Fe(η3-B5H10)!(η5-C5H5)Fe(η5-B5H10)

The experimental ferraborane thermal isomerization (η5-C5H5)Fe(η3-B5H10)→(η5-C5H5)Fe(η5-B5H10) is intriguing: quantum-chemical computations confirm experimental proposed reactant and product structures and NMR spectroscopy assignment. The borane ligand, the unknown B5H10− anion as a free species, has an inverted geometrical stability when attached to the (η5-C5H5)Fe+ moiety, with a striking planarization, leading to a more stable ferraborane complex.