Carborane: Dedicated to the Work of Professor Alan Welch

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (20 August 2021) | Viewed by 21259

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A.N.Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, Moscow, Russia
Interests: carboranes; metal complexes of polyhedral boron compound
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Institute of Chemical Sciences, School of Engineering & Physical Sciences, Heriot Watt University, Edinburgh EH14 4AS, UK
Interests: chemical crystallography; coordination chemistry; carborane structures; crystal engineering; hydrogen bonding

Special Issue Information

Dear Colleagues,

The discovery of polyhedral boron hydrides, including carboranes, was one of the most significant discoveries of 20th-century chemistry. Since then, many different derivatives of carboranes have been obtained and they remain the focus of intense research. The unusual physical and chemical properties of polyhedral boron compounds find a wide range of real and potential applications ranging from medicine to supramolecular chemistry, catalysis, and the design of new materials.

This Special Issue is devoted to research in the field of fundamental properties of, and prospects for using, polyhedral boron hydrides and, in particular, carboranes.

In this context, the aim of this Special Issue, entitled “Carboranes”, is to provide a comprehensive overview of new developments in the chemistry of carborane derivatives with special focus on their structures.

We are pleased to invite you to submit a manuscript to this Special Issue. We welcome original research papers, communications, and reviews.

Dr. Marina Yu. Stogniy
Dr. Georgina Rosair
Guest Editors

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Keywords

  • carboranes
  • metallocarboranes
  • polyhedral boron compounds
  • fundamentals
  • applications

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Published Papers (9 papers)

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Editorial

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3 pages, 182 KiB  
Editorial
Carborane: Dedicated to the Work of Professor Alan Welch
by Georgina M. Rosair and Marina Yu. Stogniy
Crystals 2021, 11(11), 1365; https://doi.org/10.3390/cryst11111365 - 9 Nov 2021
Viewed by 1290
Abstract
In the 1950s, borohydrides arose as promising components of new rocket and aviation fuels [...] Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)

Research

Jump to: Editorial

9 pages, 3309 KiB  
Communication
New Radical-Cation Salts Based on the TMTTF and TMTSF Donors with Iron and Chromium Bis(Dicarbollide) Complexes: Synthesis, Structure, Properties
by Denis M. Chudak, Olga N. Kazheva, Irina D. Kosenko, Gennady V. Shilov, Igor B. Sivaev, Georgy G. Abashev, Elena V. Shklyaeva, Lev I. Buravov, Dmitry N. Pevtsov, Tatiana N. Starodub, Vladimir I. Bregadze and Oleg A. Dyachenko
Crystals 2021, 11(9), 1118; https://doi.org/10.3390/cryst11091118 - 14 Sep 2021
Cited by 1 | Viewed by 1838
Abstract
New radical-cation salts based on tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenefulvalene (TMsTSF) with metallacarborane anions (TMTTF)[3,3′-Cr(1,2-C2B9H11)2], (TMTTF)[3,3′-Fe(1,2-C2B9H11)2], and (TMTSF)2[3,3′-Cr(1,2-C2B9H11)2] [...] Read more.
New radical-cation salts based on tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenefulvalene (TMsTSF) with metallacarborane anions (TMTTF)[3,3′-Cr(1,2-C2B9H11)2], (TMTTF)[3,3′-Fe(1,2-C2B9H11)2], and (TMTSF)2[3,3′-Cr(1,2-C2B9H11)2] were synthesized by electrocrystallization. Their crystal structures were determined by single crystal X-ray diffraction, and their electrophysical properties in a wide temperature range were studied. The first two salts are dielectrics, while the third one is a narrow-gap semiconductor: σRT = 5 × 10−3 Ohm−1cm−1; Ea ≈ 0.04 eV (aprox. 320 cm−1). Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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11 pages, 10684 KiB  
Communication
1,12-Diiodo-Ortho-Carborane: A Classic Textbook Example of the Dihalogen Bond
by Kyrill Yu. Suponitsky, Alexei A. Anisimov, Sergey A. Anufriev, Igor B. Sivaev and Vladimir I. Bregadze
Crystals 2021, 11(4), 396; https://doi.org/10.3390/cryst11040396 - 8 Apr 2021
Cited by 14 | Viewed by 2172
Abstract
The crystal structure of 1,12-diiodo-ortho-carborane 1,12-I2-1,2-C2B10H10 was determined by single crystal X-ray diffraction. In contrary to earlier studied 1,12-dibromo analogue 1,12-Br2-1,2- C2B10H10, its crystal packing is [...] Read more.
The crystal structure of 1,12-diiodo-ortho-carborane 1,12-I2-1,2-C2B10H10 was determined by single crystal X-ray diffraction. In contrary to earlier studied 1,12-dibromo analogue 1,12-Br2-1,2- C2B10H10, its crystal packing is governed by the presence of the intermolecular I⋯I dihalogen bonds between the iodine atom attached to the carbon atom (acceptor) and the iodine atom attached to the antipodal boron atom (donor) of the carborane cage. The observed dihalogen bonds belong to the II type and are characterized by classical parameters: shortened I⋯I distance of 3.5687(9) Å, C–I⋯I angle of 172.61(11)° and B–I⋯I angle of 92.98(12)°. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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14 pages, 3804 KiB  
Article
Carboranes as Lewis Acids: Tetrel Bonding in CB11H11 Carbonium Ylide
by Maxime Ferrer, Ibon Alkorta, José Elguero and Josep M. Oliva-Enrich
Crystals 2021, 11(4), 391; https://doi.org/10.3390/cryst11040391 - 7 Apr 2021
Cited by 7 | Viewed by 2760
Abstract
High-level quantum-chemical computations (G4MP2) are carried out in the study of complexes featuring tetrel bonding between the carbon atom in the carbenoid CB11H11—obtained by hydride removal in the C-H bond of the known closo-monocarbadodecaborate anion CB11H [...] Read more.
High-level quantum-chemical computations (G4MP2) are carried out in the study of complexes featuring tetrel bonding between the carbon atom in the carbenoid CB11H11—obtained by hydride removal in the C-H bond of the known closo-monocarbadodecaborate anion CB11H12(−) and acting as Lewis acid (LA)—and Lewis bases (LB) of different type; the electron donor groups in the tetrel bond feature carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, and chlorine atomic centres in neutral molecules as well as anions H(−), OH(−), and F(−). The empty radial 2pr vacant orbital on the carbon centre in CB11H11, which corresponds to the LUMO, acts as a Lewis acid or electron attractor, as shown by the molecular electrostatic potential (MEP) and electron localization function (ELF). The thermochemistry and topological analysis of the complexes {CB11H11:LB} are comprehensively analysed and classified according to shared or closed-shell interactions. ELF analysis shows that the tetrel C⋯X bond ranges from very polarised bonds, as in H11B11C:F(−) to very weak interactions as in H11B11C⋯FH and H11B11C⋯O=C=O. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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11 pages, 1453 KiB  
Article
Coordination Ability of 10-EtC(NHPr)=HN-7,8-C2B9H11 in the Reactions with Nickel(II) Phosphine Complexes
by Marina Yu. Stogniy, Svetlana A. Erokhina, Kyrill Yu. Suponitsky, Igor B. Sivaev and Vladimir I. Bregadze
Crystals 2021, 11(3), 306; https://doi.org/10.3390/cryst11030306 - 19 Mar 2021
Cited by 9 | Viewed by 2289
Abstract
The complexation reactions of nido-carboranyl amidine 10-PrNHC(Et)=HN-7,8-C2B9H11 with different nickel(II) phosphine complexes such as [(PR2R’)2NiCl2] (R = R’ = Ph, Bu; R = Me, R’ = Ph) were investigated. As a [...] Read more.
The complexation reactions of nido-carboranyl amidine 10-PrNHC(Et)=HN-7,8-C2B9H11 with different nickel(II) phosphine complexes such as [(PR2R’)2NiCl2] (R = R’ = Ph, Bu; R = Me, R’ = Ph) were investigated. As a result, a series of novel half-sandwich nickel(II) π,σ-complexes [3-R’R2P-3-(8-PrN=C(Et)NH)-closo-3,1,2-NiC2B9H10] with the coordination of the carborane and amidine components was prepared. The acidification of obtained complexes with HCl led to the breaking of the Ni-N bond with formation of nickel(II) π-complexes [3-Cl-3-R’R2P-8-PrNH=C(Et)NH-closo-3,1,2-NiC2B9H10]. The crystal molecular structure of [3-Ph3P-3-(8-PrN=C(Et)NH)-closo-3,1,2-NiC2B9H10] was determined by single crystal X-ray diffraction. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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16 pages, 5574 KiB  
Article
Tuning the Liquid Crystallinity of Cholesteryl-o-Carborane Dyads: Synthesis, Structure, Photoluminescence, and Mesomorphic Properties
by Albert Ferrer-Ugalde, Arántzazu González-Campo, José Giner Planas, Clara Viñas, Francesc Teixidor, Isabel M. Sáez and Rosario Núñez
Crystals 2021, 11(2), 133; https://doi.org/10.3390/cryst11020133 - 28 Jan 2021
Cited by 5 | Viewed by 2535
Abstract
A set of mesomorphic materials in which the o-carborane cluster is covalently bonded to a cholesteryl benzoate moiety (mesogen group) through a suitably designed linker is described. The olefin cross-metathesis between appropriately functionalized styrenyl-o-carborane derivatives and a terminal alkenyl cholesteryl [...] Read more.
A set of mesomorphic materials in which the o-carborane cluster is covalently bonded to a cholesteryl benzoate moiety (mesogen group) through a suitably designed linker is described. The olefin cross-metathesis between appropriately functionalized styrenyl-o-carborane derivatives and a terminal alkenyl cholesteryl benzoate mesogen (all type I terminal olefins) leads to the desired trans-regioisomer, which is the best-suited configuration to obtain mesomorphic properties in the final materials. The introduction of different substituents (R = H (M2), Me (M3), or Ph (M4)) to one of the carbon atoms of the o-carborane cluster (Ccluster) enables the tailoring of liquid crystalline properties. Compounds M2 and M3 show the chiral nematic (N*) phase, whereas M4 do not show liquid crystal behavior. Weaker intermolecular interactions in the solid M3 with respect to those in M2 may allow the liquid crystallinity in M3 to be expressed as enantiotropic behavior, whereas breaking the stronger intermolecular interaction in the solid state of M2 leads directly to the isotropic state, resulting in monotropic behavior. Remarkably, M3 also displays the blue phase, which was observed neither in the chiral nematic precursor nor in the styrenyl-cholesterol model (M5) without an o-carborane cluster, which suggests that the presence of the cluster plays a role in stabilizing this highly twisted chiral phase. In the carborane-containing mesogens (M2 and M3), the o-carborane cluster can be incorporated without destroying the helical organization of the mesophase. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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12 pages, 3061 KiB  
Article
Exploration of Bis(nickelation) of 1,1′-Bis(o-carborane)
by Dipendu Mandal and Georgina M. Rosair
Crystals 2021, 11(1), 16; https://doi.org/10.3390/cryst11010016 - 27 Dec 2020
Cited by 6 | Viewed by 2053
Abstract
The metalation of [Tl]2[1-(1′-3′,1′,2′-closo-TlC2B9H10)-3,1,2-closo-TlC2B9H10], with the smaller {Ni(dmpe)} fragment sourced from [Ni(dmpe)Cl2], is explored. The bis(metalated) products are obtained as a diastereoisomeric mixture. [...] Read more.
The metalation of [Tl]2[1-(1′-3′,1′,2′-closo-TlC2B9H10)-3,1,2-closo-TlC2B9H10], with the smaller {Ni(dmpe)} fragment sourced from [Ni(dmpe)Cl2], is explored. The bis(metalated) products are obtained as a diastereoisomeric mixture. These isomers were separated, fully characterised spectroscopically and crystallographically and identified as rac-[1-(1′-3′-(dmpe)-3′,1′,2′-closo-NiC2B9H10)-3-(dmpe)-3,1,2-closo-NiC2B9H10] (1) and meso-[1-(1′-3′-(dmpe)-3′,1′,2′-closo-NiC2B9H10)-3-(dmpe)-3,1,2-closo-NiC2B9H10] (2). Previously, these 3,1,2-NiC2B9-3′,1′,2′-NiC2B9 architectures (where both cages are not isomerised), were inaccessible, and thus new structures can be achieved during bis(nickelation) with {Ni(dmpe)}. Further, the metalation of the tetra-thallium salt with the bulky {Ni(dppe)} fragment sourced from [Ni(dppe)Cl2] was also studied. These bis(nickelated) products were also fully characterised and are afforded as the stereospecific species rac-[1-(1′-3′-(dppe)-3′,1′,2′-closo-NiC2B9H10)-3-(dppe)-3,1,2-closo-NiC2B9H10] (3) and [1-(2′-4′-(dppe)-4′,1′,2′-closo-NiC2B9H10)-3-(dppe)-3,1,2-closo-NiC2B9H10] (4α). In the latter metalation, compound 3 shows intramolecular dihydrogen bonding, contributing to the stereospecificity, whereas isomerisation from 3,1,2 to 4,1,2- in the 4α is related to steric relief. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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14 pages, 3459 KiB  
Article
“Free of Base” Sulfa-Michael Addition for Novel o-Carboranyl-DL-Cysteine Synthesis
by Julia Laskova, Irina Kosenko, Ivan Ananyev, Marina Stogniy, Igor Sivaev and Vladimir Bregadze
Crystals 2020, 10(12), 1133; https://doi.org/10.3390/cryst10121133 - 11 Dec 2020
Cited by 2 | Viewed by 2116
Abstract
The sulfa-Michael addition reaction was applied for the two-step synthesis of o-carboranyl cysteine 1-HOOCCH(NH2)CH2S-1,2-C2B10H11 from the trimethylammonium salt of 1-mercapto-o-carborane and methyl 2-acetamidoacrylate. To avoid the decapitation of o-carborane into its [...] Read more.
The sulfa-Michael addition reaction was applied for the two-step synthesis of o-carboranyl cysteine 1-HOOCCH(NH2)CH2S-1,2-C2B10H11 from the trimethylammonium salt of 1-mercapto-o-carborane and methyl 2-acetamidoacrylate. To avoid the decapitation of o-carborane into its nido-form, the “free of base” method under mild conditions in a system of two immiscible solvents toluene-H2O was developed. The replacement of H2O by 2H2O resulted in carboranyl-cysteine containing a deuterium label at the α-position of the amino acid 1-HOOCCD(NH2)CH2S-1,2-C2B10H11. The structure of the protected o-carboranyl cysteine was determined by single-crystal X-ray diffraction. The obtained compounds can be considered as potential agents for the Boron Neutron Capture Therapy of cancer. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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12 pages, 5516 KiB  
Article
Reactions of Experimentally Known Closo-C2B8H10 with Bases. A Computational Study
by Josef Holub, Jindřich Fanfrlík, Michael L. McKee and Drahomír Hnyk
Crystals 2020, 10(10), 896; https://doi.org/10.3390/cryst10100896 - 3 Oct 2020
Cited by 5 | Viewed by 2282
Abstract
On the basis of the direct transformations of closo-1,2-C2B8H10 with OH(−) and NH3 to arachno-1,6,9-OC2B8H13(−) and arachno-1,6,9-NC2B8H13, respectively, which were experimentally [...] Read more.
On the basis of the direct transformations of closo-1,2-C2B8H10 with OH(−) and NH3 to arachno-1,6,9-OC2B8H13(−) and arachno-1,6,9-NC2B8H13, respectively, which were experimentally observed, the DFT computational protocol was used to examine the corresponding reaction pathways. This work is thus a computational attempt to describe the formations of 11-vertex arachno clusters that are formally derived from the hypothetical closo-B13H13(2−). Moreover, such a protocol successfully described the formation of arachno-4,5-C2B6H11(−) as the very final product of the first reaction. Analogous experimental transformations of closo-1,6-C2B8H10 and closo-1,10-C2B8H10, although attempted, were not successful. However, their transformations were explored through computations. Full article
(This article belongs to the Special Issue Carborane: Dedicated to the Work of Professor Alan Welch)
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