What the study found
The study reports a fitted set of additive covalent radii for metal dimers involving group 4–8 transition metals and the actinides thorium through neptunium. These fitted values are described as typically 10–20 pm shorter than previous triple-bond radii.
Why the authors say this matters
The authors suggest the fitted radii help describe metal–metal bonding in systems with 12 valence electrons in approximately molecular orbitals. They also propose extrapolated values for suitable cases in group 3, including rare earths, and group 9 plus plutonium.
What the researchers tested
The researchers fitted additive covalent radii to a combination of experimental data, accurate ab initio computations, and more approximate density functional theory (DFT) metal–metal bond lengths. They examined dimers MM' across the listed transition-metal and actinide elements.
What worked and what didn't
The fitting produced radii values for Ti–Fe, Zr–Ru, Hf–Os, and Th–Np. The abstract does not report a direct comparison of which specific individual cases fit better or worse, beyond noting that the values are generally shorter than the earlier triple-bond radii.
What to keep in mind
The abstract gives limited detail on the specific data set, fitting procedure, and quality of agreement for individual bond systems. It also states that some values are extrapolated, so those proposed cases are not directly fitted in the same way as the main set.
Key points
- A fitted set of additive covalent radii was reported for metal dimers involving group 4–8 transition metals and Th–Np.
- The fitted radii are typically 10–20 pm shorter than previous triple-bond radii.
- The study combined experimental data, accurate ab initio computations, and approximate DFT bond lengths.
- Values were fitted for Ti–Fe, Zr–Ru, Hf–Os, and Th–Np.
- Extrapolated values were also proposed for some group 3, group 9, and plutonium cases.
Disclosure
- Research title:
- Additive covalent radii fitted for metal dimers approaching sixfold bonding
- Authors:
- Pekka Pyykkö, Michiko Atsumi
- Institutions:
- University of Helsinki, University of Oslo
- Publication date:
- 2026-02-25
- DOI:
- 10.1002/chem.70818
- OpenAlex record:
- View
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