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.

Wen-Juan Tian,Si-Dian Li,Yue-Wen Mu,Qiang Chen,Xin-Xin Tian,Hai-Gang Lu

doi:10.1038/srep37893

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.

Highlights

It is well known that boron has a strong propensity to form multicenter-two-electron bonds to compensate for its electron deficiency in both polyhedral molecules and bulk allotropes
Two cage-like cations C1 B41+ and C2 B422+ predicted at density functional theory (DFT) have been presented to the Bnq borospherene family (q =n-40) which are all composed of twelve interwoven boron double chains (BDCs) with six hexagonal or heptagonal faces[18]
Detailed investigations on the geometrical and electronic structures of multi-ring tubular clusters and their metal-centered complexes may provide key information to understand the geometrical structures and growth mechanisms of the experimentally observed single-walled and multi-walled boron nanotubes (BNTs)[28,29] and the atomically thin borophenes with or without vacancies deposited on Ag(111) substrates[30,31]

Summary

Introduction

It is well known that boron has a strong propensity to form multicenter-two-electron bonds (mc-2e bonds) to compensate for its electron deficiency in both polyhedral molecules and bulk allotropes. Based upon extensive first-principles theory calculations, we present the possibility of doping the previously predicted quasi-planar B56 (A-1)[27] with an alkaline earth metal to produce the charge-transfer PR tubular complex Ca©B56 (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped boron α-nanotube Ca©BNT(4,0) (C-1) in a bottom-up approach.

Results

Conclusion