Theoretical Study on the Regioselectivity of Leapfrog B18 and B30 Boron Sheets in Electrophilic and Nucleophilic Reactions Using DFT-Based Reactivity Indices

A combined computational and interpretational DFT study is performed to investigate the regioselectivity of B18 and B30 leapfrog boron sheets upon reaction with XH3-type electrophiles and nucleophiles (X = N, P, As, B, Al). The M062X, B3LYP, and B3LYP-D3 functionals are used combined with the 6–31+G(d,p) basis. The molecular electrostatic potential (MEP), Fukui functions, and the dual descriptor are employed to predict the local reactivity of B18 and B30. Our results reveal that both clusters are hard and prefer to react with hard bases and acids, such as NH3 and BH3. Further, these leapfrog B6n clusters can play the role of catalysts as they break B–H and Al–H bonds of BH3 and AlH3 in s-BH3–B6n and s-AlH3–B6n complexes, respectively. Leapfrog B6n–XH3 complexes (X = B and Al) can be considered as an interaction between two electron-deficient systems. Therefore, the chemical reactivity between these systems cannot be interpreted in terms of the Hard–Soft–Acid–Base principle.