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

Abstract

A combined computational and interpretational DFT study is performed to investigate the regioselectivity of B 18 and B 30 leapfrog boron sheets upon reaction with XH 3 -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 B 18 and B 30 . Our results reveal that both clusters are hard and prefer to react with hard bases and acids, such as NH 3 and BH 3 . Further, these leapfrog B 6n clusters can play the role of catalysts as they break B−H and Al−H bonds of BH 3 and AlH 3 in s-BH 3 − B 6n and s-AlH 3 −B 6n complexes, respectively. Leapfrog B 6n −XH 3 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.

An Extended Rudolph Diagram: B3H5 and B3H6+ Relate 3D-, 2D-, 1D-, and 0D-Boron Allotropes

“…The third domain in the structural variations of boron is the recently discovered flat borophenes and other variants of 2D-allotropes. − Variations of such flat structures appeared also in solution − and gas phase. − In fact, the name borophene is first suggested for the structure of B 36 generated in the gas phase . The electron count in the extended 2D structures of borophenes and their connection to graphene via MgB 2 is well established. − In borophene, the graphenic electron count is brought back if one boron atom is removed for each nine boron atom, resulting in a hexagonal hole for every nine boron atom: a hexagonal hole density (HD) of 1/9.…”