Evolution of B13n (n = + 3 to − 3) wheel with electron injection/abstraction: an insight from electronic structure analysis

Abstract

The planar B13+1 cluster, a prototypical molecular ‘Wankel motor’, has captivated the scientific community with its exceptional stability as well as rotor action. The present study is an exploration of how incremental electron injection/abstraction influences the electronic structure of B13 clusters with B13+1 as a reference one. It has been found that seven different charge states (from + 3 to − 3) of B13 cluster are possible, among which B13−1 triplet is the lowest energy cluster. For B13n clusters, n = + 3 to − 2, the clusters are planar and possess C2v symmetry and their relative atomic arrangement is similar to B13+1 ground state (GS) structure in which a triangular boron core is encircled by ten peripheral boron atoms. B13−3 cluster has a different geometric arrangement of atoms like that of the B13+1 transition state (TS) structure; remains planar, possesses C2v symmetry. The different atomic arrangement of B13−3 can be assigned to the electronic structural relaxation to reduce the electronic stress arising from high negative charge. B13+1 cluster is characterized by a unique electron density distribution in the cluster plane which is analogous to a ‘tri-spoke wheel’ configuration. In it, three spokes of electron dense lines connect the triangular core to the nearly circular periphery. The present study unveils how the injection or abstraction of electrons modifies the electronic topology in the cluster plane and how the spoke-wheel geometry evolves. It has been found that, in the + 3 and + 2 charge states, the wheel consists of four and five spokes respectively. On the other hand, for all other clusters, the overall electronic topology resembles that of the tri-spoke wheel-like B13+1 cluster. AIM analysis helped to trace out and characterize the evolution of the spoke-wheel topology with electron density at ring critical points and the bond paths.