Selecting Boron Fullerenes by Cage-Doping Mechanisms

TL;DR

This paper proposes a new stability rule for boron fullerenes, suggesting that combining cage-doping with seed clusters can enable their synthesis by reducing polymorphism and reactivity.

Contribution

It introduces the isolated filled pentagon rule (IFPR) and demonstrates how seed-induced doping combined with IFPR can facilitate boron fullerene synthesis.

Findings

IFPR predicts stable boron fullerene structures

Seed doping breaks polymorphism in boron cages

Doping reduces reactivity of boron shells

Abstract

So far, no boron fullerenes were synthesized: more compact sp3-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011)] as "seeds" for a possible synthesis which would topologically protect the sp2 sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis.