From Quasi-Planar B56 to Penta-Ring Tubular Ca©B56: Prediction of Metal-Stabilized Ca©B56 as the Embryo of Metal-Doped Boron α-Nanotubes

Abstract

Motifs of planar metalloborophenes, cage-like metalloborospherenes, and metal-centered double-ring tubular boron species have been reported. Based on extensive first-principles theory calculations, we present herein the possibility of doping the quasi-planar C2v B56 (A-1) with an alkaline-earth metal to produce the penta-ring tubular Ca©B56 (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped (4,0) boron α-nanotube Ca©BNT(4,0) (C-1). Ca©BNT(4,0) (C-1) can be constructed by rolling up the most stable boron α-sheet and is predicted to be metallic in nature. Detailed bonding analyses show that the highly stable planar C2v B56 (A-1) is the boron analog of circumbiphenyl (C38H16) in π-bonding, while the 3D aromatic C4v Ca©B56 (B-1) possesses a perfect delocalized π system over the σ-skeleton on the tube surface. The IR and Raman spectra of C4v Ca©B56 (B-1) and photoelectron spectrum of its monoanion C4v Ca©B56− are computationally simulated to facilitate their spectroscopic characterizations.

Formation of the quasi-planar B56 boron cluster: topological path from B12 and disk aromaticity

“…Also, the system contains 29 × |4c-2e| bonds with 7 located in the inner region of the cluster and other 22 bonds in the outer region of the quasi-planar system. The remaining 19 bonds have a higher number of centers than 5; thus, these electrons are the π electrons that are part of the delocalized orbitals of the model described in the present study and previously suggested by Li et al 53…”

Formation of the M2B18q Teetotum Boron Clusters with 4d and 5d Transition Metals M = Rh, Pd, Ir, and Pt

“…In fact, the B 40 cluster is known as a fullerene 8 whereas the B 56 cluster is characterized to have a quasi-planar shape. 9 Evolution of the geometric structures of the pure boron clusters is not fully understood yet. With the aim of designing small stable tubes that can be served as units for building up boron tubes, we have found that incorporation of transition metal atoms into the boron hosts can be regarded as an efficient approach.…”

“…However, these pure DR units cannot be used to make longer tubes. In fact, the B 40 cluster is known as a fullerene whereas the B 56 cluster is characterized to have a quasi-planar shape . Evolution of the geometric structures of the pure boron clusters is not fully understood yet.…”