Pentapnictogen heterocyclic monoanions: Structure, stability, and aromaticity

Abstract

Inorganic planar ring‐shape molecules with 4n + 2 π electrons are always the focus of experimental synthesis and theoretical research due to their potential aromaticity and stability. In this work, the whole series of five‐membered heterocycle monoanions X nY5‐n− (X, Y = group 15 elements; n = 1‐4) were thoroughly investigated by means of density functional theory calculations. They all have large formation energies and HOMO‐LUMO gap energies, suggesting the potential thermodynamic and kinetic stability. Their aromaticities are comparable to that of typical aromatic hydrocarbons. Their thermal stabilities were firmly established by the ab initio molecular dynamics simulations. As most of them are predicted for the first time, their various spectra were simulated for experimental characterization. Furthermore, we demonstrate that these five‐membered cyclic anions can be employed as η5‐ligand to construct novel all‐inorganic metallocenes, which may serve as the building blocks of low‐dimensional nanomaterials.

Planar inorganic five-membered heterocycles with σ + π dual aromaticity in both S0and T1states

“…Recent reports have confirmed that it can give very reasonable structures, energies and aromaticities of different planar five-membered rings comparable to the expensive coupled-cluster calculations. 35–41 It also successfully provides strong theoretical evidence for the triplet-state aromaticity 42 and the presence of adaptive aromaticity 10–14,19–21,33,34 as well as the all-metal Baird aromaticity. 43 Full geometry optimizations were carried out by using the M06-2X functional 44 and the def2-TZVPPD basis set for all the elements, with the corresponding efficient core potentials for heavier Sb and Bi.…”

Group 13 five- and six-membered rings with rare 2π aromaticity

“…Recently, we predicted a series of inorganic five-membered heterocycles containing group 15 elements or group 15/16 elements to have p aromaticity and novel adaptive s + p dual aromaticity, respectively, by using the same theoretical method. 27,28 To evaluate the feasibility of forming an inverse-sandwich structure from the isolated ring and two Na atoms, its binding energy was calculated as E b = E total -E ring -2E Na , where E total , E ring and E Na are the total energies of the whole molecule, central ring and an isolated Na atom, respectively. Similarly, for the half-sandwich structures, E b = E total -E ring -E Ca was calculated, where E Ca is the energy of an isolated Ca atom.…”

“…Recently, we predicted a series of inorganic five-membered heterocycles containing group 15 elements or group 15/16 elements to have π aromaticity and novel adaptive σ + π dual aromaticity, respectively, by using the same theoretical method. 27,28…”