Search for: All records

Strong negative charge on the tetravalent apical C of propellane can attract an electrophile, which can then extract charge from the prominent lobe of its C–C bonding orbital, to form a strong noncovalent bond with C as an electron donor. 

The occurrence of these anion⋯anion dimers in the crystal structure are dependent on the presence of counterions as the attraction between two Au(iii) centers is insufficient to override the coulombic repulsion. 

Abstract The starting point for this work was a set of crystal structures containing the motif of interaction between methyl groups in homodimers. Two structures were selected for which QTAIM, NCI and NBO analyses suggested an attractive interaction. However, the calculated interaction energy was negative for only one of these systems. The ability of methyl groups to interact with one another is then examined by DFT calculations. A series of (CH₃PnHCH₃)₂homodimers were allowed to interact with each other for a range of Pn atoms N, P, As, and Sb. Interaction energies of these C⋅⋅⋅C tetrel‐bonded species were below 1 kcal/mol, but could be raised to nearly 3 kcal/mol if the C atom was changed to a heavier tetrel. A strengthening of the C⋅⋅⋅C intermethyl bonds can also be achieved by introducing an asymmetry via an electron‐withdrawing substituent on one unit and a donor on the other. The attractions between the methyl and related groups occur in spite of a coulombic repulsion between σ‐holes on the two groups. NBO, AIM, and NCI tools must be interpreted with caution as they can falsely suggest bonding when the potentials are repulsive. 

Abstract The interaction between two square palladium (II) dianions PdX₄²⁻(X=Cl, Br) is evaluated by crystal study and analyzed by quantum chemical means. The arrangement within the crystal between each pair of PdX₄²⁻neighbors is suggestive of a Pd⋅⋅⋅X noncovalent bond, which is verified by a battery of computational protocols. While the potential between these two bare dianions is computed to be highly repulsive, the introduction of even just two counterions makes this interaction attractive, as does the presence of a constellation of point charges. It is concluded that there is indeed a stabilizing Pd⋅⋅⋅X bond, but it is incapable of overcoming the strong coulombic repulsive force between two dianions. While the QTAIM, NBO, and NCI tools can indicate the presence of a noncovalent bond, they are unable to distinguish an attractive from a repulsive interaction. 

Inert noble gas atoms are engaged in different forms of halonium cations. Attractive X⋯Ng interactions can vary widely in strength from 1 even up to 25 kcal mol⁻¹. 

The wolfium bond is a recently described noncovalent interaction in which metals belonging to group 6 act as electron acceptors. 

In the investigated complexes, the metal atom acts as a Lewis base, with the occupied d_z²orbital serving as the source of charge transferred to the Lewis acid.