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Abstract The triel bond (TrB) formed between Be(CH3)2/Mg(CH3)2and TrX3(Tr=B, Al, and Ga; X=H, F, Cl, Br, and I) is investigated via the MP2/aug‐cc‐pVTZ(PP) quantum chemical protocol. The C atoms of the methyl groups in M(CH3)2are characterized by a negative electrostatic potential and act as an electron donor in a triel bond with the π‐hole above the Tr atom of planar TrX3. The interaction energy spans a wide range between −2 and −69 kcal/mol. Mg(CH3)2forms a stronger TrB than does Be(CH3)2, which comports with the more negative electrostatic potential on its methyl groups. Some of the complexes involving Mg display a high degree of transfer of the methyl group from Mg to Tr, which is accompanied by an inversion of the bridging methyl and a sizable pyramidalization of the TrX3unit. The geometries of these complexes have the properties of the long sought pentacoordinate C which has eluded identification and characterization in the past.
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Weak σ‐Hole Triel Bond between C 5 H 5 Tr (Tr=B, Al, Ga) and Haloethyne: Substituent and Cooperativity Effects
Abstract The replacement of a CH group of benzene by a triel (Tr) atom places a positive region of electrostatic potential near the Tr atom in the plane of the aromatic ring. This σ‐hole can interact with an X lone pair of XCCH (X=F, Cl, Br, and I) to form a triel bond (TrB). The interaction energy between C5H5Tr and FCCH lies in the range between 2.2 and 4.4 kcal/mol, in the order Tr=B+cation above the ring pulls density toward itself and thus magnifies the Tr σ‐hole. The TrB to the XCCH nucleophile is thereby magnified as is the strength of the TrB. This positive cooperativity is particularly large for Tr=B.
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- Award ID(s):
- 1954310
- PAR ID:
- 10257534
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhysChem
- Volume:
- 22
- Issue:
- 5
- ISSN:
- 1439-4235
- Format(s):
- Medium: X Size: p. 481-487
- Size(s):
- p. 481-487
- Sponsoring Org:
- National Science Foundation
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