From a Möbius-aromatic interlocked Mn2B10H10 wheel to the metal-doped boranaphthalenes M2@B10H8 and M2B5 2D-sheets (M = Mn and Fe): a molecules to materials continuum using DFT studies

• Published in: Chemical science (Cambridge) 2022-08, Vol.13 (31), p.8968-8978
• Main Authors: Ghorai, Sagar, Jemmis, Eluvathingal D
• Format: Article
• Language: English
• Subjects: Aromaticity; Boron; Chemistry; Coupling (molecular); Crystal structure; Electronic structure; Electrons; Graphene; Iron; Manganese; Monolayers; Naphthalene; Orbital stability; Planar structures; Search algorithms; Solid state; Structural analysis
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d2sc02244c

The inherent tendency of BR fragments to undergo coupling is utilized to predict M2B10H10 and M2@B10H8 complexes (where M = Mn and Fe). Electronic structure analysis of Mn2B10H10 (7) shows that the metal d-orbitals stabilize the interlocked boron wheel structure, forming an unprecedented geometrical pattern with Möbius aromaticity. The two additional electrons in Fe2@B10H10 (8) stabilize a twisted [10]boraannulene structure. The removal of 2H from 7 and 8 leads to the planar structures Mn2@B10H8 (11) and Fe2@B10H8 (10), respectively. The stability of the planar arrangements is due to multicentered (σ + π) bonding, where π-donation occurs from the M2 (M = Fe and Mn) unit to the borocyclic unit. The presence of 10π electrons in M2@B10H8 relates it to naphthalene, having Hückel π-aromaticity. The condensation of naphthalene to graphene in two dimensions suggests the ability to build the different metal boride monolayers FeB5 and Fe2B5, considering Fe2@B10 as the building block, bringing this molecular boron chemistry into the solid state. One of the predicted monolayers, β-Fe2B5, is found to be the global minimum in the planar arrangement based on a USPEX crystal structure search algorithm. Electronic structure analysis further shows that the stabilization mechanism in the molecular building block remains unaltered in the solid state.