Search

Using the experimentally known aromatic icosahedral superatoms Ih B12H122− and D5d 1,12-C2B10H12 as building blocks and based on extensive density functional theory calculations, we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach, including the high-symmetry Th B12@B152H722− (2), C2h C2B10@B152H72 (3), D3d B12@B144H66 (4), Ih B12@C24B120H722− (6), and D5d C2B10@C24B120H72 (7). More interestingly, the superatom-assembled linear D2h B36H322− (8), close-packed planar D3dB84H602− (10), and nearly close-packed core–shell D3d B12@B144H66 (4) can be extended periodically to form the one-dimensional (1D) α-rhombohedral borane nanowire B12H10 (Pmmm) (9), two-dimensional (2D) α-rhombohedral monolayer borophane B12H6 (P 3 ¯ m 1 ) (11), and the experimentally known three-dimensional (3D) α-rhombohedral boron (R 3 ¯ m ) (12) which can be viewed as an assembly of the monolayer B12H6 (11) staggered in vertical direction, setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane "seeds" via partial or complete dehydrogenations. Detailed bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B12 or C2B10 structural units which possess the universal skeleton electronic configuration of 1S21P61D101F8 following the Wade's n+1 rule. The infrared (IR) and Raman spectra of the most-concerned neutral B12@B144H66 (4) and C2B10@C24B120H72 (7) are computationally simulated to facilitate their experimental characterizations. [ABSTRACT FROM AUTHOR]

Based on extensive global minimum searches augmented with first-principles theory calculations, we predict herein the first boron-based perfect tetrahedral clusters Td B16P4 (2) and Td B16As4 (3) which, as aromatic non-metal analogs of the experimentally observed Td Au20 (2003, Science299, 864), all contain a truncated Td B16 (1) cage at the center effectively stabilized by four trivalent non-metal atoms (P, As) at the corners. Detailed natural bonding orbital (NBO) and adaptive natural density partitioning (AdNDP) bonding analyses indicate that the valences of all the trivalent component atoms in these tetrahedral clusters are fully satisfied, rendering spherical aromaticity and extra stability to the systems. The IR, Raman, and photoelectron spectra (PES) of the concerned species are theoretically simulated to facilitate their characterizations in future experiments. [ABSTRACT FROM AUTHOR]

Extensive global minimum searches augmented with first-principles theory calculations performed in this work indicate that the experimentally observed perfect inverse sandwich lanthanide boride complexes D7h La2B7− (1), D8h La2B8 (3), D9h La2B9− (7) can be extended to their actinide counterparts C2v Ac2B7− (1′), D8h Ac2B8 (3′), D9h Ac2B9− (7′) with a Bn monocyclic ring (n = 7–9) sandwiched by two Ac dopants. Such M2Bn−/0 inverse sandwiches (1/1′, 3/3′, 7/7′) can be used as building blocks to generate the ground-state C2 La4B13− (2)/Ac4B13− (2′), D2 La4B15− (4)/Ac4B15− (4′), C3v/C3 La4B18 (5)/Ac4B18 (5′), Oh Ac7B24+ (6′), Oh Ac7B24, Td Ac4B24 (8′), C1 La5B24+ (9)/Ac5B24+ (9′), and Td Ac4B29− (10′) which are based on boron frameworks consisting of multiple conjoined Bn rings (n = 7–9). Detailed bonding analyses show that effective (d–p)σ, (d–p)π and (d–p)δ coordination bonds are formed between the Bn rings and metal doping centers, conferring three-dimensional aromaticity and extra stability to the systems. In particular, the perfect body-centered cubic Oh Ac7B24+ (6′) and Oh Ac7B24 with six conjoined B8 rings can be extended in x, y, and z dimensions to form one-dimensional Ac10B32 (11′), two-dimensional Ac3B10 (12′), and three-dimensional AcB6 (13′) nanomaterials, presenting a B8-based bottom-up approach from metal boride nanoclusters to their low-dimensional nanomaterials. [ABSTRACT FROM AUTHOR]

It is well-known that transition-metal-doping induces dramatic changes in the structures and bonding of small boron clusters, as demonstrated by the newly observed perfect inverse sandwich D8h [La(η8-B8)La] and D9h [La(η9-B9)La]−. Based on extensive global minimum searches and first-principles theory calculations, we predict herein the possibility of perfect endohedral trihedral metallo-borospherene D3h La@[La5&B30] (1, 3A′1) and its monoanion Cs La@[La5&B30]− (2, 2A′) and dianion D3h La@[La5&B30]2− (3, 1A′1). These La-doped boron clusters are composed of three inverse sandwich La(η8-B8)La on the waist and two inverse sandwich La(η9-B9)La on the top and bottom which share one apex La atom at the center and six periphery B2 units between neighboring η8-B8 and η9-B9 rings, with three octo-coordinate La atoms and two nona-coordinate La atoms as integrated parts of the cage surface. Detailed adaptive natural density partitioning (AdNDP) and iso-chemical shielding surface (ICSS) analyses indicate that La@[La5&B30]0/−/2− (1/2/3) are spherically aromatic in nature. The one-dimensional nanowire La4B21 (4, P31m) constructed from D3h La@[La5&B30] (1) along the C3 axis of the system appears to be metallic. The IR and Raman spectra of La@[La5&B30] (1) and photoelectron spectroscopy of the slightly distorted Cs La@[La5&B30]− (2) are theoretically simulated to facilitate their spectroscopic characterizations. [ABSTRACT FROM AUTHOR]

The successive discoveries of the cage-like D2d B40−/0 and C3/C2 B39− mark the onset of borospherene chemistry. Based on extensive global minimum searches and first-principles theory calculations, we predict herein the possible existence of the axially chiral cage-like C2 B38+ (1/1′) and C2 B382+ (3/3′) which are novel aromatic members of the borospherene family featuring a B21 boron triple-chain on the waist and four B6 hexagonal holes on the cage surface. Detailed bonding analyses show that the B38+ (1) and B382+ (3) possess 12 and 11 delocalized π bonds over a σ-skeleton, respectively, following the universal bonding pattern of σ + π double delocalization of the borospherene family. Extensive molecular dynamics simulations indicate that both B38+ (1) and B382+ (3) are dynamically stable at 700 K. The IR, Raman, and UV–vis spectra of these cluster cations are computationally simulated to facilitate their future spectral characterizations. [ABSTRACT FROM AUTHOR]

The newly discovered cage-like borospherene D2d B40 with two η6-B6 hexagons and four η7-B7 heptagons on the surface may serve as an effective multi-dentate ligand to coordinate transition metals. Based upon extensive density functional theory calculations, we present herein the possibility of the exohedral complex series (C6H6Cr)n&B40 (n = 1–6) with n Cr centres sandwiched between the central η6/7-B40 unit and n planar η6-C6H6 ligands. C6H6Cr fragments in (C6H6Cr)n&B40 occupy the η6-B6 hexagonal coordination site atop the B40 cage first, the four neighboring η7-B7 heptagons on the waist next, and finally the η6-B6 hexagon at the bottom, forming a multinuclear complex series effectively stabilized by n C6H6Cr fragments. The two η6-B6 hexagons and four η7-B7 heptagons on the spherical surface of B40 can be practically viewed as six independent coordination sites to coordinate Cr centers with almost the same coordination energies. Detailed bonding analyses indicate that the eclipsed C2v C6H6Cr&B40 (1-1) possesses a coordination bonding pattern similar to that of dibenzenechromium, with the B40 ligand inheriting the σ + π double delocalization bonding pattern of the parent borospherene. The IR, Raman, and UV–vis absorption spectra of C2v C6H6Cr&B40 (1-1) are theoretically simulated to facilitate its future experimental characterization. [ABSTRACT FROM AUTHOR]

Boron nanoclusters and few‐layer borophenes have received considerable attention in recent years due to their unique structural and bonding patterns. Based on extensive global searches and density‐functional theory calculations, we present herein the possibility of a new series of bilayer medium‐sized boron clusters including C2 B54 (I), C2h B60 (II), and C1 B62 (III) in a universal structural pattern, with one, two, and three B6 hexagonal windows on the waist around a B38 bilayer hexagonal prism at the center, respectively. Detailed orbital and bonding analyses indicate that these three‐dimensional aromatic bilayer clusters follow the σ + π double delocalization bonding pattern, with three or four effective interlayer B–B σ‐bonds formed to further stabilize the system. The IR, Raman, and UV/Vis spectra of the bilayer species are theoretically simulated to facilitate their future spectral characterizations. [ABSTRACT FROM AUTHOR]

The structure, electronic, magnetic properties of SinMn clusters up to n=15 are systematically investigated using the density functional theory within the generalized gradient approximation. In the most stable configurations of SinMn clusters, the equilibrium site of Mn atom gradually moves from convex, to a surface, and to a concave site as the number of Si atoms varying from 1 to 15. Starting from n=11, the Mn atom completely falls into the center of the Si outer frame, forming Mn-encapsulated Si cages. Maximum peaks of second-order energy difference are found at n=6, 8, 10, and 12, indicating that these clusters possess relatively higher stability. The electronic structures and magnetic properties of SinMn clusters are discussed. The magnetic moment of SinMn clusters mainly is located on Mn atom. The 3d electrons in Mn atom play a dominant role in the determination of the magnetism of Mn atom in SinMn clusters. Furthermore, the moment of Mn atom in SinMn clusters exhibits oscillatory behavior and are quenched at n>7 except for n=12, mainly due to the charge transfer, strong hybridization between Mn 4s, 3d, 4p and Si 3s, 3p states. [ABSTRACT FROM AUTHOR]