Ab Initio Study of Benzene−BX₃ (X = H, F, Cl) Interactions

Abstract

Quantum mechanical ab initio calculations at the MP2/6-311++G** level of theory have been used to predict the binding energies and geometries of benzene−BX3 and ethene−BX3 (X = H, F, Cl) complexes. Single point calculations at a much higher level of correlation (MP4) and larger basis sets (6-311++G(2df,p) + diffuse(d,p)) have also been carried out. The calculations reveal interesting trends in their binding energies and geometries. The binding energies indicate that all of them are weakly bound van der Waals complexes with the exception of the C2H4−BH3 complex. While complexes involving BF3 are the weakest (binding energies) in cases of both ethene and benzene, there is a reversal in the relative order of the binding energies as one moves from ethene to benzene. Thus C6H6−BCl3 is more tightly bound than C6H6−BH3. The geometry exhibited by the lowest energy conformer in cases of complexes involving benzene is different from those involving ethene. In contrast to most weak van der Waals interactions involving benzene, H−π, and aromatic−aromatic, the boron atom lies directly over one of the benzene carbons. This observation has been explained by comparing the geometries obtained in complexes involving both benzene and ethene. More importantly, there is strong evidence of an unusual increase in the nucleophilicity of one of the benzene carbons in the lowest energy conformer of systems involving benzene, which implies that Lewis acid−aromatic ring interactions have an important role in electrophilic aromatic substitution reactions.

Understanding Clusters toward the Design of Functional Molecules and Nanomaterials

“…38,39 Unlike in the case of ionwater clusters, there are little changes in the gross structural features of the water clusters in their complexed states with 1700 2100 2500 2900 3300 3700 100K (9) 145K ( the systems because the interactions existing between water molecules in these clusters are much stronger than the interactions between the water clusters and the systems. 125,126 Another interesting finding from our calculations of the benzene interacting with Lewis acids (halides of aluminium, boron, and hydrogen) [127][128][129] was that the interaction energies are large (8-15 kcal mol À1 ) among neutral interactions. The importance of the proposed -Lewis acid interactions in understanding the nature of catalysts and ionic liquids was highlighted by Olah et al 130 and Seddon and Earle.…”

Electrosyntheses of Freestanding and Conducting Poly[poly(N-vinyl-carbazole)] Films in Tetrahydrofuran Containing Additional Boron Trifluoride Diethyl Etherate

“…As a Lewis acid, BF 3 can interact with a Lewis base, such as thiophene, benzene, fused ring compound, etc. 37,38 This interaction can decrease the resonance energy of these aromatic compound, thus leading the lose of an electron from these compounds much easier and making high quality conducting polymer films formation possible. On the other hand, this interaction leads to the significant decrease of oxidation onset potential of monomer.…”

The structural properties of boron and nitrogen adsorption on benzene molecule: a density functional study

“…A quantum mechanical ab initio calculations of benzene-BX 3 (X=H, F, Cl) interaction at the level of Mp2/6-311? ?G**, was performed by Tarakeshwar et al [7]. They also carried out some singlepoint calculations at a much higher level of correlation with larger basis set (MP4/6-311?…”