Balancing Donor‐Acceptor and Dispersion Effects in Heavy Main Group Element π Interactions: Effect of Substituents on the Pnictogen⋅⋅⋅π Arene Interaction

Abstract

High-level ab initio calculations using the DLPNO-CCSD(T) method in conjunction with the local energy decomposition (LED) were performed to investigate the nature of the intermolecular interaction in bismuth trichloride adducts with π arene systems. Special emphasis was put on the effect of substituents in the aromatic ring. For this purpose, benzene derivatives with one or three substituents (R = NO 2 , CF 3 , OCHO, OH, and NH 2) were chosen and their influence on donoracceptor interaction as well as on the overall interaction strength was examined. Local energy decomposition was performed to gain deeper insight into the composition of the interaction. Additionally, the study was extended to the intermolecular adducts of arsenic and antimony trichloride with benzene derivatives having one substituent (R = NO 2 and NH 2) in order to rationalize trends in the periodic table. The analysis of natural charges and frontier molecular orbitals shows that donor-acceptor interactions are of π!σ* type and that their strength correlates with charge transfer and orbital energy differences. An analysis of different bonding motifs (Bi•••π arene, Bi•••R, and Cl•••π arene) shows that if dispersion and donoracceptor interaction coincide as the donor highest occupied molecular orbital (HOMO) of the arene is delocalized over the π system, the M•••π arene motif is preferred. If the donor HOMO is localized on the substituent, R•••π arene bonding motifs are preferred. The Cl•••π arene bonding motif is the least favorable with the lowest overall interaction energy.

Evaluation of bismuth-based dispersion energy donors – synthesis, structure and theoretical study of 2-biphenylbismuth(iii) derivatives

“…Scheme 2 Different dispersion adducts of aromatic systems with trivalent heavy pnictogen compounds (EX 3 ). 16,20,34,35…”

“…41 Compound 1 shows an encapsulation of the bismuth atom by the 2-biphenyl ligands (BiÁ Á ÁPh centroid : 3.99 Å, 4.04 Å and 4.06 Å), however, the BiÁ Á ÁPh centroid distances are found close to 4.0 Å, which can be considered as the limit of significant London dispersion interaction for these systems based on previous theoretical work. 35 However, the structure of 1 revealed 1D ribbon-like structures ( Fig. S4(i), ESI †) which are formed via C-HÁ Á ÁPh centroid intermolecular contacts with a distance of C24-H24Á Á ÁPh centroid 2.55 Å and an angle g = 5.61 between the ring normal and the vector between the ring centroid and the hydrogen atom.…”

“…Note that previous studies have shown that this level of theory provides a good balance between computational effort and accuracy in comparison to high-level methods. 34,35 The structural parameters, i.e. the computed BiÁ Á ÁPh centroid distances and the Bi-C-C angle, are displayed in Fig.…”

“…In conjunction with aromatic substituents that optimises the donor properties of the arene interaction energies of up to 70 kJ mol À1 can be obtained. 35 In order to quantify and rationalize the BiÁ Á Áp arene interaction studied here, we focus on compound 3. For this purpose, a model structure was constructed that allows to interpret the intermolecular interaction at the DLPNO-CCSD(T) level of theory applying the local energy decomposition (LED).…”

Dispersion interaction of the type-bismuth···π arene in substituted bismuthines

“…This might be due to the influence of the substituent X on the benzyl ligand as recently reported in a theoretical study with focus on BiCl 3 adducts with various substituted benzenes. 43 This assumption is supported by the…”