Triple-chain boron clusters: lengthening via phosphorus doping and enhancing stability through {P} by {CH} substitution

This theoretical study presents novel insights into the doping of boron clusters with an increasing number of dopant atoms, ranging from 1 to 4, that preserve the integrity of the original boron framework. The triple-chain forms of clusters B10 and B16 remain unchanged upon sequential addition of P atoms, showcasing a perfect isolobal substitution of {P} with {CH}. Similarities in the number of delocalized electrons are observed between pure and doped boron clusters, alongside the subsequent substitution of {P} with {CH}. All triple-chain structures exhibit high thermodynamic stability, having low vertical attachment energies and high vertical ionization energies. The lowest-lying isomer of B16P4 has thus a triple-chain shape instead of a tetrahedral Td form as previously reported. While AdNDP analysis confirms the number of globally delocalized electrons, it differs much from a previous interpretation. The magnetic ring current maps support the double aromaticity of triple-chain structures. Electron counting rules established for triple-chain structures are verified. The particle-in-a-rectangular-box model elucidates the relationship between the structure size and electron configuration and aids in understanding the transition from antiaromatic to aromatic configurations. The self-locking phenomenon is crucial for adhering to the triple chain model and satisfying electron configuration requirements.