Heptacoordinate transition-metal-decorated metallo-borospherenes and multiple-helix metallo-boronanotubes

• Published in: Nanoscale 2023-02, Vol.15 (5), p.2377-2383
• Main Authors: Ao, Mei-Zhen, Zhang, Fei, Ma, Yuan-Yuan, Mu, Yue-Wen, Li, Si-Dian
• Format: Article
• Language: English
• Subjects: Aromaticity; Bonding; Boron; Coordination; Decoration; Elongated structure; First principles; Ligands; Metallography; Nanomaterials; Transition metals
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d2nr05486h

The recent discovery of lanthanide-metal-decorated metallo-borospherenes LM 3 B 18 − (LM = La, Tb) marks the onset of a new class of boron-metal binary nanomaterials. Using the experimentally observed or theoretically predicted borospherenes as ligands and based on extensive first-principles theory calculations, we predict herein a series of novel chiral metallo-borospherenes C 2 Ni 6 ∈ B 39 − ( 1 ), C 1 Ni 6 ∈ B 41 + ( 3 ), C 2 Ni 6 ∈ B 42 2+ ( 4 ), C 2 Ni 6 ∈ B 42 ( 5 ), and C 2 Ni 8 ∈ B 56 ( 6 ) as the global minima of the systems decorated with quasi-planar heptacoordinate Ni (phNi) centers in η 7 -B 7 heptagons on the cage surfaces, which are found to be obviously better favoured in coordination energies than hexacoordinate Ni centers in previously reported D 2d Ni 6 ∈ B 40 ( 2 ). Detailed bonding analyses indicate that these phNi-decorated metallo-borospherenes follow the σ + π double delocalization bonding pattern, with two effective (d-p)σ coordination bonds formed between each phNi and its η 7 -B 7 ligand, rendering spherical aromaticity and extra stability to the systems. The structural motif in elongated axially chiral Ni 6 ∈ B 42 2+ ( 4 ), Ni 6 ∈ B 42 ( 5 ), and Ni 8 ∈ B 56 ( 6 ) can be extended to form the metallic phNi-decorated boron double chain (BDC) double-helix Ni 4 ∈ B 28 (2, 0) ( P 4&cmb.macr; m 2) ( 8 ), triple-helix Ni 6 ∈ B 42 (3, 0) ( P 3&cmb.macr; m 1) ( 9 ), and quadruple-helix Ni 8 ∈ B 56 (4, 0) ( P 4 mm ) ( 10 ) metallo-boronanotubes, which can be viewed as quasi-multiple-helix DNAs composed of interconnected BDCs decorated with phNi centers in η 7 -B 7 heptagons on the tube surfaces in the atomic ratio of Ni : B = 1 : 7. Extensive first-principles theory calculations predict the possibility of a series of novel heptacoordinate Ni-decorated cage-like metallo-borospherenes and one-dimensional multiple-helix metallo-boronanotubes composed of interconnected boron double chains.