Designing a Four-Ring Tubular Boron Motif through Metal Doping

Abstract

Tubular boron clusters represent a class of extremely unusual geometries that can be regarded as a key indicator for the 2D-to-3D boron structural evolution as well as the embryos for boron nanotubes. While a good number of pure boron or metal-doped boron tubular clusters have been reported so far, most of them are two-ring tubular structures, and their higherring analogues are very scarce. We report herein the first example of a four-ring tubular boron motif in the cagelike global minimum of Be 2 B 24 + . Globalminimum searches of MB 24 q and M 2 B 24 q (M = alkali/alkaline-earth metals; q = 1+, 0, 1−) reveal that the most stable structure of Be 2 B 24 + is a C 2v -symmetric cage having a four-ring tubular boron moiety, whereas it is a high-lying isomer for those having a two/three-ring tubular boron motif for all other systems. The B 24 framework in Be 2 B 24 + can be viewed as consisting of two two-ring B 12 tubular structures linked together at one side of the B 6 rings along the highsymmetry axis and two offside B 6 rings capped by two Be atoms. The Be 2 −B 24 bonding is best described as Be 2 2+ in an excited triplet state, forming two highly polarized covalent bonds with B 24 − in a quartet spin state. The unique ability of beryllium to make strong covalent and electrostatic interactions makes the Be 2 B 24 + cluster stable in such an unusual geometry.

B7Be6B7: A Boron‐Beryllium Sandwich Complex

“…To address this issue, we sought to identify an element capable of forming strong bonds with boron without forming of B−B bonds between B n units. Our previous studies have shown that beryllium can form strong covalent and electrostatic bonds with boron atoms, making it a promising candidate [36–38] . Herein, we explore the use of Be m rings to hinder the fusion of boron motifs and facilitate the formation of boron‐beryllium‐boron sandwich complexes.…”

“…Our previous studies have shown that beryllium can form strong covalent and electrostatic bonds with boron atoms, making it a promising candidate. [36][37][38] Herein, we explore the use of Be m rings to hinder the fusion of boron motifs and facilitate the formation of boron-beryllium-boron sandwich complexes. We consider boron motifs (up to 14 boron atoms) interacting with beryllium Be m rings, where m in Be m B n corresponds to the number of peripheral BÀ B bonds in the B n wheels.…”

Transition Metal Behavior of Heavier Alkaline Earth Elements in Doped Monocyclic and Tubular Boron Clusters

“…Recent research has unveiled a diverse array of novel geometries and electronic properties within boron clusters when TMs are introduced, owing to the strong d π –p interactions occurring between the d orbitals of TMs and the delocalized π + σ orbitals of boron motifs. − These compounds include transition metal-centered monocyclic rings in M©B n – , tubular structures (CoB 16 – and MnB 16 – ), , and lanthanide (Ln)-based inverse sandwich-type structures (Ln 2 B n – , n = 7–9). , In these TM-doped boron clusters, the critical role played by the d orbitals of TMs in fostering delocalized bonding is responsible for their stability and high symmetry. , These attractive findings in transition metal-doped boron clusters, coupled with the significance of d orbitals in heavier Ae metals, serve as a motivating factor for exploring the use of heavier Ae metals in designing captivating geometries in Ae-doped boron clusters, and further understanding the role of d orbitals of heavier Ae metals in the delocalized bonding. It is already known that the use of electro-positive dopants like alkali metal and beryllium could result in drastic structural changes in boron moieties, leading to many intriguing geometries. − …”

Structural Evolution and Electronic Properties of Two Sulfur Atom-Doped Boron Clusters

“…27 + have a four-ring tubular structure. 50 However, nonmetallic atom-doped boron clusters have been less studied, 51−56 such as single O atom doping can adjust the quasi-planar pure boron cluster (B 12 ) to a lowsymmetry (C 1 ) B 12 O cluster 53 and different numbers of F atom doping can adjust the quasi-planar pure boron cluster (B 12 ) to various unique structures. 51 In addition, there are some related studies on boron oxide clusters and boron sulfide clusters, such as the B 6 (BO) 7…”

“…In recent years, researchers have mainly focused on the structure and properties of boron clusters doped with metal atoms. ,− ,− For example, single alkali metal atom doping can adjust the quasi-planar pure boron clusters (B 20 – and B 22 – ) to double-ring tubular doped boron clusters (LiB 20 – , NaB 22 – and KB 22 – ). ,,, Single transition metal atom doping can adjust quasi-planar B 12 0/– to semisandwich structure CoB 12 , RhB 12 and TaB 12 – , ,, ,, adjust double-ring tubular B 24 to cage-doped boron clusters (TiB 24 ) and three-ring tubular doped boron clusters (ScB 24 ), ,, adjust quasi-planar B 24 – to cage-doped boron clusters (TiB 24 – and VB 24 – ). , In addition, doped borospherenes MB 40 (M = Li, Na, or K) are expected to be applied in nonlinear optical materials, doped borospherenes CoB 40 and MB 40 (M = Sc, Ti) are expected to be applied in molecular devices and hydrogen storage materials, ,,, and Co- and Rh-doped boron clusters MB 12 – (M = Co, Rh) can improve chemical activity . Single metal atom-doped boron clusters BiB n – ( n = 6–8), MnB n – ( n = 6, 16), and ReB n – ( n = 3–4, 6, 8–9), CoB 16 – and two or three metal atom-doped boron clusters (M 2 B 6 (M = Mg, Ca, Sr), La 2 B 10 – , La 2 B 11 – , La 3 B 18 – , and Sc 3 B 20 ) have various unique structures. − ,, Single Pr atom-doped PrB 4 – can adjust the Pr atom to a very low oxidation state (OS) and single Pr atom-doped PrB n ( n = 7–16) have various unique structures; two metal atom-doped boron clusters Be 2 B 24 + have a four-ring tubular structure . However, nonmetallic atom-doped boron clusters have been less studied, − such as sin...…”