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Keywords = polyhedral closo-borane

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17 pages, 2498 KiB  
Article
The Reaction of Hydrogen Halides with Tetrahydroborate Anion and Hexahydro-closo-hexaborate Dianion
by Igor E. Golub, Oleg A. Filippov, Natalia V. Belkova, Lina M. Epstein and Elena S. Shubina
Molecules 2021, 26(12), 3754; https://doi.org/10.3390/molecules26123754 - 20 Jun 2021
Cited by 10 | Viewed by 2931
Abstract
The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH4]− by hydrogen halides (HX, X = F, Cl, Br) and hexahydro-closo-hexaborate dianion [B6H6]2− by HCl via electrophile-induced nucleophilic substitution (EINS) was established [...] Read more.
The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH4]− by hydrogen halides (HX, X = F, Cl, Br) and hexahydro-closo-hexaborate dianion [B6H6]2− by HCl via electrophile-induced nucleophilic substitution (EINS) was established by ab initio DFT calculations [M06/6-311++G(d,p) and wB97XD/6-311++G(d,p)] in acetonitrile (MeCN), taking into account non-specific solvent effects (SMD model). Successive substitution of H− by X− resulted in increased electron deficiency of borohydrides and changes in the character of boron atoms from nucleophilic to highly electrophilic. This, in turn, increased the tendency of the B–H bond to transfer a proton rather than a hydride ion. Thus, the regularities established suggested that it should be possible to carry out halogenation more selectively with the targeted synthesis of halogen derivatives with a low degree of substitution, by stabilization of H2 complex, or by carrying out a nucleophilic substitution of B–H bonds activated by interaction with Lewis acids (BL3). Full article
(This article belongs to the Special Issue Transition Metal and Main Group Hydrides: Structure, Reactivity, and Applications)
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20 pages, 3121 KiB  
Article
Thermodynamic Hydricity of Small Borane Clusters and Polyhedral closo-Boranes
by Igor E. Golub, Oleg A. Filippov, Vasilisa A. Kulikova, Natalia V. Belkova, Lina M. Epstein and Elena S. Shubina
Molecules 2020, 25(12), 2920; https://doi.org/10.3390/molecules25122920 - 25 Jun 2020
Cited by 14 | Viewed by 4617
Abstract
Thermodynamic hydricity (HDAMeCN) determined as Gibbs free energy (ΔG°[H]−) of the H− detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral closo-boranes dianions [BnHn] [...] Read more.
Thermodynamic hydricity (HDAMeCN) determined as Gibbs free energy (ΔG°[H]−) of the H− detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral closo-boranes dianions [BnHn]2−, and their lithium salts Li2[BnHn] (n = 5–17) by DFT method [M06/6-311++G(d,p)] taking into account non-specific solvent effect (SMD model). Thermodynamic hydricity values of diborane B2H6 (HDAMeCN = 82.1 kcal/mol) and its dianion [B2H6]2− (HDAMeCN = 40.9 kcal/mol for Li2[B2H6]) can be selected as border points for the range of borane clusters’ reactivity. Borane clusters with HDAMeCN below 41 kcal/mol are strong hydride donors capable of reducing CO2 (HDAMeCN = 44 kcal/mol for HCO2−), whereas those with HDAMeCN over 82 kcal/mol, predominately neutral boranes, are weak hydride donors and less prone to hydride transfer than to proton transfer (e.g., B2H6, B4H10, B5H11, etc.). The HDAMeCN values of closo-boranes are found to directly depend on the coordination number of the boron atom from which hydride detachment and stabilization of quasi-borinium cation takes place. In general, the larger the coordination number (CN) of a boron atom, the lower the value of HDAMeCN. Full article
(This article belongs to the Special Issue Boron Chemistry and Its Development in the 21st Century: In Memory of Professor Bohumil Štíbr (1940-2020))
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13 pages, 1708 KiB  
Article
Dihydrogen Bonds in Salts of Boron Cluster Anions [BnHn]2− with Protonated Heterocyclic Organic Bases
by Varvara V. Avdeeva, Anna V. Vologzhanina, Elena A. Malinina and Nikolai T. Kuznetsov
Crystals 2019, 9(7), 330; https://doi.org/10.3390/cryst9070330 - 28 Jun 2019
Cited by 21 | Viewed by 3601
Abstract
Dihydrogen bonds attract much attention as unconventional hydrogen bonds between strong donors of H-bonding and polyhedral (car)borane cages with delocalized charge density. Salts of closo-borate anions [B10H10]2− and [B12H12]2− with protonated organic [...] Read more.
Dihydrogen bonds attract much attention as unconventional hydrogen bonds between strong donors of H-bonding and polyhedral (car)borane cages with delocalized charge density. Salts of closo-borate anions [B10H10]2− and [B12H12]2− with protonated organic ligands 2,2’-dipyridylamine (BPA), 1,10-phenanthroline (Phen), and rhodamine 6G (Rh6G) were selectively synthesized to investigate N−H...H−B intermolecular bonding. It was found that the salts contain monoprotonated and/or diprotonated N-containing cations at different ratios. Protonation of the ligands can be implemented in an acidic medium or in water because of hydrolysis of metal cations resulting in the release of H3O+ cations into the reaction solution. Six novel compounds were characterized by X-ray diffraction and FT-IR spectroscopy. It was found that strong dihydrogen bonds manifest themselves in FT-IR spectra that allows one to use this technique even in the absence of crystallographic data. Full article
(This article belongs to the Special Issue Chemical Bonding in Crystals and Their Properties)
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85 pages, 36438 KiB  
Review
Silver and Copper Complexes with closo-Polyhedral Borane, Carborane and Metallacarborane Anions: Synthesis and X-ray Structure
by Varvara V. Avdeeva, Elena A. Malinina, Igor B. Sivaev, Vladimir I. Bregadze and Nikolai T. Kuznetsov
Crystals 2016, 6(5), 60; https://doi.org/10.3390/cryst6050060 - 20 May 2016
Cited by 72 | Viewed by 10324
Abstract
Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10] [...] Read more.
Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10]−, carba-closo-dodecaborate [CB11H12]−, and cobalt bis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− anions and their derivatives, are reviewed. The complexes demonstrate a wide variety of structural types, relating to both the metal coordination environment and coordination modes of boron hydride anions. The latter can range from strong coordination via the polyhedron triangular face including formation of 3c-2e MHB bonds in the case of the [B10H10]2− dianion, the structure of which contains two four-coordinated boron atoms, to very weak M…H interactions with the hydride atoms in the case of bulky [3,3′-Co(1,2-C2B9H11)2]− monoanion. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
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