A series of 12-phenyl-closo-thiaboranes (12-(4-X-C6H4)-closo-1-SB11H10, where X = OMe (2), X = SMe (3), X = Ph (4), and X = NMe2 (5)) has been prepared. Except for 2, all compounds exhibit a chalcogen bond of thiaborane to the phenyl ring or the neighboring molecule as major supramolecular structural motif. 5, having the strongest (-12.47 kcal/mol) structure-making intermolecular interaction via noncovalent S···π(phenyl) chalcogen bond, was crystallized from different solvents in the form of various solvatopolymorphs. n-Hexane and diethyl ether can be removed from 5 easily upon the formation of a porous material with large cavities (up to 20.5% of the unit cell). This first stable and useful noncovalently bound organic framework material with an ultramicroporous structure exhibits a molecular sieve effect. The selective and repeatable adsorption of CO2 to the material crystallized from n-hexane was explained on the basis of cooperative and consecutive machine-like molecular interactions of quadrupolar CO2 molecule with B-H and amino groups inside rectangular cavities.

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• Journal Article MeSH

Borane and heteroborane clusters have been known as neutral or anionic species. In contrast to them, several ten-vertex monocationic nido and closo dicarbaborane-based systems have recently emerged from the reaction of the parent bicapped-square antiprismatic dicarbaboranes with N-heterocyclic carbenes followed by the protonization of the corresponding nido intermediates. The expansion of these efforts has afforded the very first closo-dicationic octahedral phosphahexaborane along with new closo-monocationic pnictogenahexaboranes of the same shapes. All are the products of the one-pot procedure that consists in the reaction of the same carbenes with the parent closo-1,2-Pn2B4Br4 (Pn = As, P). Whereas in the case of phosphorus such a monocation appears to be a mixture of stable intermediates, and arsenahexaboranyl monocation has occurred as the final product, all of them without using any subsequent reaction. The well-established DFT/ZORA/NMR approach has unambiguously confirmed the existence of these species in solution, and computed electrostatic potentials have revealed the delocalization of the positive charge in these monocations and in the very first dication, namely within the octahedral shapes in both cases.

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• Journal Article MeSH

Modern computational protocols based on the density functional theory (DFT) infer that polyhedral closo ten-vertex carboranes are key starting stationary states in obtaining ten-vertex cationic carboranes. The rearrangement of the bicapped square polyhedra into decaborane-like shapes with open hexagons in boat conformations is caused by attacks of N-heterocyclic carbenes (NHCs) on the closo motifs. Single-point computations on the stationary points found during computational examinations of the reaction pathways have clearly shown that taking the "experimental" NHCs into account requires the use of dispersion correction. Further examination has revealed that for the purposes of the description of reaction pathways in their entirety, i.e., together with all transition states and intermediates, a simplified model of NHCs is sufficient. Many of such transition states resemble in their shapes those that dictate Z-rearrangement among various isomers of closo ten-vertex carboranes. Computational results are in very good agreement with the experimental findings obtained earlier.

• Keywords
• DFT, N-heterocyclic carbenes, carboranes, cations, reaction pathways,
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• Journal Article MeSH

Chalcogen atoms are a class of substituents capable of generating inner and outer derivatives of boron clusters. It is well known that chalcogenated boron clusters can form strong σ-hole interactions when a chalcogen atom is a part of an icosahedron. This paper studies σ-hole interactions of dicarbaboranes with two exopolyhedral chalcogen atoms bonded to carbon vertices. Specifically, a computational investigation has been carried out on the co-crystal of (1,2-C2B10H10)2Se4•toluene and a single crystal of (1,2-C2B10H10)2Te4.

• Keywords
• co-crystal, heteroborane, sigma hole,
• MeSH
• Boranes chemistry   MeSH
• Chalcogens chemistry   MeSH
• Crystallization MeSH
• Models, Molecular MeSH
• Static Electricity MeSH
• Thermodynamics MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Boranes MeSH
• Chalcogens MeSH

Electrophilic methylation of the closo-1,10-R2C2B8H8 (1) (R = H or Me) dicarbaboranes at higher temperatures or thermal rearrangement of the 1,6-R2C2B8Me8 (3) compounds at 400-500 °C generated the B-permethylated derivatives closo-1,10-R2C2B8Me8 (2) in quantitative (>95%) yields. The compounds exhibit extreme air stability as a consequence of a rigid, egg shaped hydrocarbon structures incorporating inner 1,10-C2B8 carborane core.

• Publication type
• Journal Article MeSH