Bonding and Reactivity in RB-As R Systems(R=H,F,OH,CH_3,CMe_3,CF_3,SiF_3,BO): Substituent Effects

Density functional theory-based calculations have been carried out to study the bonding and reactivity in RB-AsR (R=H, F, OH, CH₃, CMe₃, CF₃, SiF₃, BO) systems. Our calculations demonstrated that all the studied systems adopted bent geometry (∠R-B-As ≈ 180° and ∠B-As-R ≈ 90° or less). The reason for this bending was explained with the help of a valence-orbital model. The potential energy surfaces for three possible isomers of RB-AsR systems were also generated, indicating that the RB-AsR isomer was more stable than R₂B-AsR when R=SiF₃, CMe₃, and H. The B-As bond character was analyzed using natural bond orbital (NBO) and Wiberg bond index (WBI) calculations. The WBI values for B-As bonds in F₃SiB-AsSiF₃ and HB-AsH were 2.254 and 2.209, respectively, indicating that this bond has some triple-bond character in these systems. While the B centers prefer nucleophilic attack, the As centers prefer electrophilic attack.