Ferrocene at 75: lessons from fifteen years of experiment–theory convergence

Abstract

Ferrocene has long served both as a historical model and a benchmark system for experimental and theoretical methodologies in organometallic chemistry. This review examines how the long-standing ambiguity surrounding Fc conformation has been resolved through high-accuracy X-ray spectroscopy and the identification of a symmetry-driven infrared (IR) signature near 450 cm−1, which provides a definitive spectroscopic fingerprint of the eclipsed (D5h) conformer. Crucially, this feature reflects the Fe-centred electronic response rather than marginal conformer energy differences. After briefly outlining key milestones in Fc structural determination, we focus on a fifteen-year program integrating h..