The Journal of Chemical Physics
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The ability of the F atom of HC≡CF, H2C=CHF and H3CCH2F to serve as an electron donor to the triel (Tr) atom of TrR3 in the context of a triel bond is assessed by ab initio calculations. The triel bond formed by Csp3—F is strongest, as high as 30 kcal/mol, followed by Csp2—F, and then by Csp—F whose triel bonds can be as small as 1 kcal/mol. The noncovalent bond strength diminishes in the order Tr = Al > Ga > B, consistent with the intensity of the π-hole above the Tr atom in the monomer. The triel bond strength of the Al and Ga complexes increases along with the electronegativity of the R substituent but is largest for R=H when Tr=B. Electrostatics play the largest role in the stronger triel bonds, but dispersion makes an outsized contribution for the weakest such bonds.
Yang, Qingqing, Chi, Zongqing, Li, Qingzhong and Steve, Scheiner. "Effect of Carbon Hybridization in C—F Bond as an Electron Donor in Triel Bonds." The Journal of Chemical Physics, vol. 153, no. 7, 2020, pp. 074304-1-074304-9. https://doi.org/10.1063/5.0018950
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