Bonding and Reactivity in RB-AsR Systems (R = H, F, OH, CH3, CMe3, CF3, SiF3, 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 (angle R-B-As approximate to 180 degrees and angle B-As-R approximate to 90 degrees 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.