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Here we show that substituting the ten protons in the dianion of a bispentalene derivative (C18H102−) by six Si2+ dications produces a minimum energy structure with two planar tetracoordinate carbons (ptC). In Si6C18, the ptCs are embedded in the terminal C5 pentagonal rings and participate in a three‐center, two‐electron (3c‐2e) Si‐ptC‐Si σ‐bond. Our exploration of the potential energy surface identifies a triphenylene derivative as the putative global minimum. Nevertheless, robustness to Born–Oppenheimer molecular dynamics (BOMD) simulations at 900 and 1500 K supports bispentalene derivative kinetic stability. Chemical bonding analysis reveals ten delocalized π‐bonds, which, according to Hückel's 4n + 2 π‐electron rule, would classify it as an aromatic system. Magnetically induced current density analysis reveals the presence of intense local paratropic currents and a weakly global diatropic current, the latter agreeing with the possible global aromatic character of this specie. [ABSTRACT FROM AUTHOR]

This work proposes a new molecular orbital localization procedure. The approach is based on the decomposition of the overlap matrix in accordance with the partitioning of the three-dimensional physical space into basins with clear chemical meaning arising from the topological analysis of the electron localization function. The procedure is computationally inexpensive, provides a straightforward interpretation of the resulting orbitals in terms of their localization indices and basin occupancies, and preserves the σ/π-separability in planar N-electron systems. The localization algorithm is tested on selected molecular systems. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In this study, we report about the relativistic effects on the aromaticity of borazine, B3N3H6, and their halogenated derivatives (B3N3F6, B3N3Cl6, B3N3Br6, B3N3I6, and B3N3At6), via the magnetically‐induced current density method. All‐electron density functional theory calculations were carried out using the four‐component Dirac‐Coulomb hamiltonian, including scalar and spin‐orbit relativistic effects. Ring current strengths were obtained by numerical integration over the current flow. These values were compared to the spin‐free (scalar relativistic) and nonrelativistic values, to assess the corresponding contributions to aromaticity. It was found that in B3N3I6 and B3N3At6 there exists a significant spin‐orbit influence, in line with the expected relativistic effects associated to the heavy elements, iodine, and astatine. Borazine, B3N3H6, is known to be slightly aromatic, but much less aromatic than benzene. The application of an external magnetic field induces a current density, that accounts for the delocalization and mobility of electrons in a molecule. Using this theoretical method, the aromaticity of the derivatives B3N3X6(X = H, F, Cl, Br, I, At) was investigated. The inclusion of heavy elements requires a relativistic treatment where the spin‐orbit coupling must be included. The figure shows the three‐dimensional pathways of the current density flow in B3N3At6. The any particle molecular orbital (APMO) approach extends regular electronic structure methods to study atomic and molecular systems in which electrons and other particles are treated simultaneously as quantum waves. A number of electronic structure methodologies have been extended under the APMO framework and applied to investigate nuclear quantum effects, proton binding energies and affinities, and physical and chemical properties of atomic and molecular systems containing exotic subatomic particles. [ABSTRACT FROM AUTHOR]