Predicting bilayer B50, B52, B56, and B58: structural evolution in bilayer B48–B72 clusters

Abstract

The successive experimental observations of planar, cage-like, seashell-like, and bilayer B n -/0 clusters in the size range between n = 3-48 well demonstrate the structural diversity and rich chemistry of boron nanoclusters. Based on extensive global minimum search and density functional theory calculations, we predict herein the bilayer C 1 B 50 (I), C 2h B 52 (II), C 1 B 56 (IV), and C 2v B 58 (V) as the global minima of the systems to ll in the missing gap in the bilayer B 2n series between B 48 -B 72 . These highly stable species all contain a B 38 bilayer hexagonal prism at the center, with 2, 2, 3, and 3 effective interlayer B-B σ-bonds formed between inward-buckled atoms on the top and bottom layers, respectively. Our bilayer C 1 B 50 (I) and C 1 B 56 (IV) prove to be obviously more stable than the previously reported monolayer planar C 2v B 50 and C 2v B 56 with two adjacent B 6 hexagonal holes. Detailed bonding analyses indicate that these bilayer clusters follow the universal bonding pattern of σ + π double delocalization, making them threedimensionally aromatic in nature. The bilayer B 2n species in the size range between B 48 -B 72 evolve gradually on the waist around the B 38 or elongated B 46 bilayer hexagonal prism at the center.

A bottom-up approach from medium-sized bilayer boron nanoclusters to bilayer borophene nanomaterials

“…The BL B 84 –B 98 species discussed above also turn out to be highly dynamically stable during extensive BOMD simulations, as demonstrated in the cases of high-symmetry C 2 v B 86 ( II ) and C 2 v B 96 ( VII ) in Fig. S4† which have the small average root-mean-square-deviations of RMSD = 0.15 and 0.12 Å and maximum bond length deviations of MAXD = 0.79 and 0.66 Å at 1000 K and 700 K, respectively, similar to the situations in the previously reported BL B 48 –B 72 12,23–25 series. No lower-lying isomers were observed during MD simulations in 30 ps.…”

“…1) with two staggered B 6 hexagonal holes on the top and bottom layers. 14,23–25 The formations of five interlayer B–B σ-bonds between the top and bottom layers and two staggered B 6 hexagonal holes on the top and bottom layers effectively help to stabilize the system.…”

“…Global searches on B 84 , B 86 , B 88 , B 90 , B 92 , B 94 , B 96 , and B 98 were performed using both the TGMin2 program 43 and Minima Hopping algorithms, 44 in conjunction with extensive manual structural constructions based on the previously predicted BL B 48 –B 72 . 12,23–25 Low-lying isomers were firstly re-optimized at the PBE0/6-31G(d) level, with vibrational frequencies being checked to ensure that all isomers obtained were true minima of the systems. The relative energies were further refined for the first two lowest-lying isomers at both PBE0/6-311+G(d) 45,46 and TPSSh/6-311+G(d).…”

“…Various supported 2D ML borophenes including α-sheets on the Ag(111) substrate have been synthesized later in MBE experiments. 20,21 The bilayer (BL) structural motif firstly observed in B 48 −/0 12,22 has been extended recently to a series of novel BL boron clusters by our group at the density functional theory (DFT) level in the size range between B 50 and B 72 including C 1 B 50 , C 2 h B 52 , C 2 B 54 , C 1 B 56 , C 2 v B 58 , C 2 h B 60 , C 1 B 62 , C 2 B 64 , D 2 B 66 , D 2 B 68 , C 1 B 70 , and C i B 72 23–25 which are all the global minima (GMs) of the systems effectively stabilized by interlayer B–B σ-bonds between inward-buckled boron atoms on the top and bottom layers. These BL species follow the universal bonding pattern of σ + π double delocalization, making them three-dimensionally (3D) aromatic in nature.…”

La@[La5&B30]0/−/2−: endohedral trihedral metallo-borospherenes with spherical aromaticity

“…3–8 The newly discovered bilayer motif has been recently extended to a large size range of even numbered neutral boron clusters between B 48 –B 72 at density functional theory (DFT) level. 9–11 Ion mobility and theoretical calculations, on the other hand, showed that B n + monocations possess tubular structures in the size range n = 16–25. 12 Perfect cage-like B 80 has also been proposed at density functional theory (DFT) 13,14 level which was later found to favor core–shell structures in thermodynamics.…”