Issue 5, 2024

Nature and strength of group-14 A–A′ bonds


We have quantum chemically investigated the nature and stability of C–C and Si–Si bonds in R3A–AR3 (A = C, Si; R3 = H3, Me3, Me2Ph, MePh2, Ph3, t-Bu3) using density functional theory (DFT). Systematic increase of steric bulk of the substituents R has opposite effects on C–C and Si–Si bonds: the former becomes weaker whereas the latter becomes stronger. Only upon going further, from R = Ph to the bulkiest R = t-Bu, the R3Si–SiR3 bond begins to weaken. Our bonding analyses show how different behavior upon increasing the steric bulk of the substituents stems from the interplay of (Pauli) repulsive and (dispersion) attractive steric mechanisms. Extension of our analyses to other model systems shows that C–Si bonds display behavior that is in between that of C–C and Si–Si bonds. Further increasing the size of the group-14 atoms from C–C and Si–Si to Ge–Ge, Sn–Sn and Pb–Pb leads to a further decrease in the sensitivity of the bond strength with respect to the substituents' bulkiness. Our findings can be used as design principles for tuning A–A and A–A′ bond strengths.

Graphical abstract: Nature and strength of group-14 A–A′ bonds

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Article information

Article type
Edge Article
20 Nov 2023
07 Jan 2024
First published
16 Jan 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2024,15, 1648-1656

Nature and strength of group-14 A–A′ bonds

D. Rodrigues Silva, E. Blokker, J. M. van der Schuur, T. A. Hamlin and F. M. Bickelhaupt, Chem. Sci., 2024, 15, 1648 DOI: 10.1039/D3SC06215E

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