Abstract
The gas-phase acidity of ferrocene (Î"H°acid(1) = 391.5 ± 1.3 kcal mol-1) and electron affinity of the ferrocenyl radical (EA(1r) = 1.74 ± 0.08 eV) were measured in a Fourier transform mass spectrometer and combined in a thermodynamic cycle with the known ionization energy of the hydrogen atom to afford the C-H bond dissociation energy of 1 (BDE(1) = 118.0 ± 2.3 kcal mol-1). Companion M06-2X but not B3LYP computations reproduce each of these thermodynamic quantities and are in accord with an unusually strong aromatic C-H BDE. Natural population analysis and atomic polar tensor charges indicate that a covalent description of ferrocene with a neutral iron atom is a better representation of this compound than an ionic one with a doubly charged Fe2+ center. Predicted structural differences upon deprotonation of MCp2, M = Fe and Mg, are also in accord with this view.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 6016-6021 |
| Number of pages | 6 |
| Journal | Journal of Physical Chemistry A |
| Volume | 123 |
| Issue number | 28 |
| DOIs | |
| State | Published - Jul 18 2019 |
Bibliographical note
Funding Information:Generous support from the National Science Foundation (CHE-1665392) and the Minnesota Supercomputer Institute for Advanced Computational Research is gratefully acknowledged.
Publisher Copyright:
© 2019 American Chemical Society.