Superhalogen Anions Supported by the Systems Comprising Alternately Aligned Boron and Nitrogen Central Atoms

Using DFT/(B3LYP/wB97XD/B2PLYPD) and OVGF electronic structure methods with flexible atomic orbital basis sets, we examined the series of polynuclear superhalogen anions matching the (BF₃(BN) _n F_4n+1)^- formula (for n = 1-10,13,18-20) containing alternately aligned boron and nitrogen central atoms decorated with fluorine ligands. It was found that the equilibrium structures of these anions correspond to fully extended chains (with each B and N central atom surrounded by four substituents arranged in a tetrahedral manner) and thus mimic the globally stable fully extended (all-trans) conformations of higher n-alkanes. The vertical electron detachment energies of the (BF₃(BN) _n F_4n+1)^- anions were found to exceed 8 eV in all cases and gradually increase with the increasing number of n. The approximate limiting value of vertical electron binding energy that could be achieved for such polynuclear superhalogen anions was estimated as equal to ca. 10.7 eV.

Crown-like charge-transfer lithium-doped boron oxide complexes B8O2Li+/0

A variety of researches on boron oxide clusters have indicated the key role of boronyl (BO) group in the structures and bonding. Based upon global structural searches and electronic structure calculations at the B3LYP and single-point coupled cluster single double (triple) (CCSD(T)) levels, we present the possibility of construction of lithium-doped boron oxide B₈O₂Li^+/0 clusters (1-2). Different from the structures of pure B₆^+/0/- and B₆(BO)₂^0/-, the B₈O₂Li^+/0 which can be formulated as B₆(BO)₂Li^+/0 are not the double-chain structures, they are the crown-like structure, and the Li is like a diamond that links the crown. Detailed AdNDP analyses indicate the π aromaticity of B₈O₂Li⁺ (1). The results obtained in this work reveal that the metal could influence the structures and properties of boron oxides significantly.

Boron-based inorganic heterocyclic clusters: electronic structure, chemical bonding, aromaticity, and analogy to hydrocarbons

This Perspective article deals with recent computational and experimental findings in boron-based heterocyclic clusters, which focuses on binary B-O and B-S clusters, as well as relevant ternary B-X-H (X = O, S, N) species. Boron is electron-deficient and boron clusters do not form monocyclic rings or linear chains. Boron-based heterocyclic clusters are intuitively even more electron-deficient and feature exotic chemical bonding, which make use of O 2p, S 3p, or N 2p lone-pairs for π delocalization over heterocyclic rings, facilitating new cluster structures and new types of bonding. Rhombic, pentagonal, hexagonal, and polycyclic clusters are discussed herein. Rhombic species are stabilized by four-center four-electron (4c-4e) π bonding, that is, the o-bond. An o-bond cluster differs from a typical 4π antiaromatic system, because it has 4π electrons in an unusual bonding/nonbonding combination, which takes advantage of the empty 2p_z atomic orbitals from electron-deficient boron centers. A variety of examples (notably including boronyl boroxine) possess a hexagonal ring, as well as magic 6π electron-counting, making them new members of the inorganic benzene family. Pentagonal clusters bridge rhombic o-bond systems and inorganic benzenes, but they do not necessarily favor 6π electron-counting as in cyclopentadienide anion. In contrast, pentagonal 4π clusters are stable, leading to the concept of pentagonal o-bond. One electron can overturn the potential energy landscape of a system, enabling rhombic-to-hexagonal structural transition, which further reinforces the idea that 4π electron-counting is favorable for rhombic systems and 6π is magic for hexagonal rings. The bonding analogy between heterocyclic clusters and hydrocarbons goes beyond monocyclic species, which allows rational design of boron-based inorganic analogs of polycyclic aromatic hydrocarbons, including s-indacene as a puzzling aromatic/antiaromatic system. Selected linear B-O clusters are also briefly discussed, featuring dual 3c-4e π bonds, that is, ω-hyperbonds. Dual ω-hyperbonds, rhombic or pentagonal o-bond, and inorganic benzenes share a common chemical origin. The field of boron-based heterocyclic clusters is still in its infant stage, and much new chemistry remains to be discovered in forthcoming experimental and theoretical studies.

A photoelectron spectroscopy and quantum chemical study on ternary Al–B–O clusters: AlnBO2− and AlnBO2 (n = 2, 3)

Dictated by sequential and competitive oxidation of B versus Al centers, ternary Al₂BO₂^−/0 and Al₃BO₂^−/0 clusters do not possess a BO₂ unit despite its structural robustness.

Structural and bonding properties of BS−/0 and BS3−/0

The structures of BS⁻ and BS₃⁻ were determined by the combination of size-selected anion photoelectron spectroscopy and theoretical calculations.

Double-ring tubular (B2O2)n clusters (n = 6-42) rolled up from the most stable BO double-chain ribbon in boron monoxides

Based on extensive global searches and first-principles theory calculations, we present herein the possibility of double-ring tubular (B₂O₂)_n clusters (n = 6-42) (2-10) rolled up from the most stable one-dimensional (1D) BO double-chain ribbon (1) in boron monoxides. Tubular (3D) (B₂O₂)_n clusters (n ≥ 6) are found to be systematically much more stable than their previously proposed planar (2D) counterparts, with a 2D-3D structural transition at B₁₂O₁₂ (2). Detailed bonding analyses on 3D (B₂O₂)_n clusters (2-10) and their precursor 1D BO double-chain ribbon (1) reveal two delocalized B-O-B 3c-2e π bonds over each edge-sharing B₄O₂ hexagonal unit which form a unique 6c-4e o-bond to help stabilize the systems. The IR, Raman, UV-vis, and photoelectron spectra of the concerned species are computationally simulated to facilitate their experimental characterization.

Superhalogen properties of BS2(-) and BSO(-): photoelectron spectroscopy and theoretical calculations

We investigate BS2(-) and BSO(-) clusters using photoelectron spectroscopy and theoretical calculations. The electron affinities of BS2 and BSO are measured to be 3.80 ± 0.03 and 3.88 ± 0.03 eV, respectively, higher than those of halogen atoms. Thus, BS2 and BSO can be considered as superhalogens. The comparison of experimental and theoretical results confirmed that the ground state structures of BS2(-), BSO(-), and their neutrals are all linear. Analyses of natural bond orbitals suggest that both BS2(-) and BSO(-) have dual 3c-4e π hyperbonds.

Planar B3S2H3−and B3S2H3clusters with a five-membered B3S2ring: boron–sulfur hydride analogues of cyclopentadiene

Boron–sulfur hydride clusters,C_2vB₃S₂H₃⁻and B₃S₂H₃, possess a five-membered B₃S₂ring as the core, which is analogous to cyclopentadiene in terms of π bonding.

Probing the structural and electronic properties of doped gallium oxide and sulfide, M(GaX2)2 where M = alkali or coinage metal; X = O, S

A theoretical study on the equilibrium geometries, vibrational frequencies and electronic features of a series of doped gallium oxide and sulfide clusters, M(GaX₂)₂ (M = alkali or coinage metal; X = O or S), was conducted.

Boronyl as a terminal ligand in boron oxide clusters: hexagonal ring C2vB6O4and ethylene-like D2hB6O4−/2−

Planar boron boronyl B₆O₄^0/−/2−clusters are predicted. B₆O₄is an inorganic analogue of benzene, whereas B₆O₄^−/2−are ethylene-like with open structures.

On the structure and bonding in the B4O4+cluster: a boron oxide analogue of the 3,5-dehydrophenyl cation with p and s double aromaticity

The B₄O₄⁺cluster has a hexagonal structure with a boroxol ring. It features double (p and s) aromaticity, akin to the 3,5-dehydrophenyl cation.