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In the current work, the authors analyzed and compared the chemical behavior of some (anti)aromatic compounds. The species selected are benzene and cyclobutadiene as the aromatic and antiaromatic classical examples, respectively. Next, the anion Al42−, which is the first all‐metal molecule catalogued as aromatic and its non‐metallic isoelectronic analog, B42− were also analyzed. The antiaromatic clusters Al44− and B44− were studied in form of lithium salts. And the end, the non‐planar B12 boron cluster and its isoelectronic analogs (B11Be− and B11C+) were considered for being analyzed under the same criterium. The analysis was realized employing the following descriptors: molecular electrostatic potential and local hyper‐softness to get insights concerning local reactivity when facing reagents leading to ionic or covalent interactions. The results show that all the molecules analyzed presented some specific variations in their respective local reactivity despite being labeled as aromatic compounds. This analysis provides a notion that the local reactivity is more based on the nature of the atoms and the molecular geometry than the aromatic character by itself. [ABSTRACT FROM AUTHOR]

In the current work, a new family of isoelectronic analogues to B12 is reported. The construction of this family was performed through the isoelectronic substitution principle to generate species such as B11C+, B11Be−, B10BeC, B10C22+, B10Be22− B9Be2C−, and B9BeC2+. The search for the global minimum was realized by utilizing genetic algorithms, while the induced magnetic field, electronic localization function, magnetic current densities, and multicenter aromaticity criteria were calculated to understand their electronic delocalization. Our results show that, in general, C atoms avoid hypercoordination, whereas we have found species with Be atoms located in hypercoordinated positions that are relatively stable. Our analysis of aromaticity indicates that B12 has double σ and π disk aromaticity. Mono, double or triple substitution of B by C+ or Be− reduces somewhat the aromaticity of the clusters, but less in the case of Be− substitution. [ABSTRACT FROM AUTHOR]

Inspired by carbo-benzene and its inorganic analogues, in the current work, the viability of extended systems (called carbomers) formed from aromatic small rings was studied. The aluminum aromatic cluster, Al42−, and its isoelectronic carbon analogue, C42+, were employed as starting point. The insertion of alkynyl units into the Al-Al and C-C bonds results in the extended molecules named carbomers. These molecules were compared with the global minima structures, which were searched employing the genetic algorithm program, GEGA. The electronic delocalization (aromaticity) of the isomers was studied with the induced magnetic field (Bind). The results showed that global minimum of C122+ (formed from C42+) was an unexpected diatropic structure which presented a similar magnetic response to the C42+ cluster. Also, optical properties of C122+ were computed. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, we report a simple experimental strategy for the one‐step electrochemical synthesis of nanogranular Cu2O films by copper anodization in fluoride‐containing ethylene glycol media. Microscopic exploration using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM), shows the formation of spherical shape grains with sizes ranging from 20 to 40 nm. Raman and X‐Ray Photoemission Spectroscopy (XPS) results indicate that only CuI oxide is obtained. A band gap energy Eg=2.01 eV is estimated from UV–vis reflectance spectroscopy indicating that an indirect transition mechanism between semiconductor bands takes place. These evidences indicate that the present synthesis of nanogranular Cu2O films is a promising method for obtaining improved properties of materials for the design of photoelectronic devices. [ABSTRACT FROM AUTHOR]

The stability of the LinBnH2n (n = 3–6) series was analyzed using quantum chemical calculations, and it was found that cyclic isomers are not energetically favored. This is different to what happens in their organic counterparts (CnH2n), where cyclopentane (C5H10) and cyclohexane (C6H12) are the low-lying isomers. Apparently, aromaticity is a key-stabilizing factor that needs to be considered for designing stable lithium-boron hydride analogues of cyclic organic compounds. This is verified in the Li3B3H3+ system, which has been designed as the smallest aromatic carbocation (C3H3+) analogue. The global minimum structure of Li3B3H3+ contains a triangular B3H32− moiety, which has structural and chemical bonding features similar to its organic counterpart. Besides, this new cluster is classified as aromatic according to both the 4n + 2 Hückel rule and the analysis of the induced magnetic field. This theoretical evidence leads us to propose this cluster as a viable target for experimental detection in the gas phase. [ABSTRACT FROM AUTHOR]

The potential energy surfaces (PESs) of Lin(BH)5n−6 systems (where n = 5, 6, and 7) were explored using the gradient embedded genetic algorithm (GEGA) program, in order to find their global minima conformations. This search predicts that the lowest-energy isomers of Li6(BH)5 and Li7(BH)5+ contain a (BH)56− pentagonal fragment, which is isoelectronic and structurally analogous to the prototypical aromatic hydrocarbon anion C5H5−. Li7(BH)5+, along with Li7C5+, Li7Si5+ and Li7Ge5+, joins a select group of clusters that adopt a seven-peak star-shape geometry, which is favored by aromaticity in the central five-membered ring, and by the preference of Li atoms for bridging positions. The theoretical analysis of chemical bonding, based on magnetic criteria, supports the notion that electronic delocalization is an important stabilization factor in all these star-shaped clusters. [ABSTRACT FROM AUTHOR]

The potential energy surfaces of a series of clusters with the formula CAl3E (E = P, As, Sb, Bi) are systematically explored using density functional theory and high level ab initio calculations. The global minimum structure of these clusters contains a planar tetracoordinate carbon atom. The presence of a C=E double bond is supported by the Wiberg bond indices, the adaptive natural density partitioning analysis, and the magnetic response. Our results show that these planar tetracoordinate carbon clusters are both thermodynamically and kinetically viable species in the gas phase. [ABSTRACT FROM AUTHOR]

The potential energy surfaces of a series of clusters with formula CBe5Linn−4 (n = 1 to 5) have been systematically explored. Our computations show that the lithium cations preserve the CBe54− pentagon, such that the global minimum structure for these series of clusters has a planar pentacoordinate carbon (ppC) atom. The systems are primarily connected via a network of multicenter σ-bonds, in which the C atom acts as σ-acceptor and this acceptance of charge is balanced by the donation of the 2pz electrons to the π-cloud. The induced magnetic field analysis suggests that the clusters with formula CBe5Linn−4 (n = 1 to 5) are fully delocalized. The fact that these ppC-containing clusters are the lowest-energy forms on the corresponding potential energy surfaces raises expectations that these species can be prepared experimentally in the gas phase. [ABSTRACT FROM AUTHOR]

The B19- anion and other boron species have been dubbed 'Wankel motors' for the almost barrierless rotation of inner and outer concentric rings relative to each other in these compounds. A single substitution in B19- is shown to shut down the well-established fluxionality in the anion. A carbon atom substituted in the structure to give a neutral CB18 species is shown computationally to enforce bond localization. [ABSTRACT FROM AUTHOR]

A new algorithm called Automatic Johnson Cluster Generator (AJCG) is presented, which, as its name indicates, allows the definition of the desired Johnson polyhedron to subsequently carry out all the possible permutations between the atoms that form this polyhedron. This new algorithm allows the exhaustive study of the structures' potential energy surface (PES). In addition, the AJCG algorithm is helpful for the study of three-dimensional compounds such as boranes or Zintl clusters and their structural derivatives with two or more different atoms. The automatic filling of vertices is particularly useful in mixed compounds because of the possibility of taking into account all possible configurations in the structure. As a test system, we investigated the arachno -type E 6 M 2 4- (E = Si, Ge, Sn; M = Sb, Bi) structure which has eight vertices and complies with Wade-Mingos rules. Initially, we defined a bipyramidal structure (10 vertices), and filled the vertices with the atoms in all possible configurations. Since the selected system has eight atoms, the two remaining vertices were filled with pseudo atoms to complete the structure. After re-optimizing the initial population generated with AJCG, a large number of isomers with energy below 10 kcal mol -1 are identified. These results show that the most stable isomers possess homonuclear M-M bonds, except Sn 6 Bi 2 4- . Although the overall putative minima differ at the PBE0-D3 and DLPNO-CCSD(T) levels, they are always competitive minima. In addition to using high-precision methodologies to correctly study relative energies, applying solvent effects in highly charged systems becomes mandatory. The aromatic character of these studied systems was demonstrated qualitatively with two- and three-dimensional mapping and quantitatively by calculating the value of the z-component of the induced magnetic field at the cage center, including scalar and spin-orbit correction for relativistic effects. The compounds studied have a high degree of aromaticity, which allows us to establish that despite structural modifications ( i.e. , from closo to arachno ), the aromaticity is preserved., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In the current work, a new family of isoelectronic analogues to B12 is reported. The construction of this family was performed through the isoelectronic substitution principle to generate species such as B11C+, B11Be-, B10BeC, B10C22+, B10Be22- B9Be2C-, and B9BeC2+. The search for the global minimum was realized by utilizing genetic algorithms, while the induced magnetic field, electronic localization function, magnetic current densities, and multicenter aromaticity criteria were calculated to understand their electronic delocalization. Our results show that, in general, C atoms avoid hypercoordination, whereas we have found species with Be atoms located in hypercoordinated positions that are relatively stable. Our analysis of aromaticity indicates that B12 has double σ and π disk aromaticity. Mono, double or triple substitution of B by C+ or Be- reduces somewhat the aromaticity of the clusters, but less in the case of Be- substitution.

The B19(-) anion and other boron species have been dubbed 'Wankel motors' for the almost barrierless rotation of inner and outer concentric rings relative to each other in these compounds. A single substitution in B19(-) is shown to shut down the well-established fluxionality in the anion. A carbon atom substituted in the structure to give a neutral CB18 species is shown computationally to enforce bond localization.