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Keller W, Sárosi MB, Fanfrlík J, Straka M, Holub J, McKee ML, Hnyk D. Boron-based octahedral dication experimentally detected: DFT surface confirms its availability. RSC Adv 2023; 13:19627-19637. [PMID: 37388141 PMCID: PMC10305729 DOI: 10.1039/d3ra03665k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/20/2023] [Indexed: 07/01/2023] Open
Abstract
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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Affiliation(s)
- Willi Keller
- Institut für Chemie, Universität Hohenheim Garbenstrasse 30 D-70599 Stuttgart Germany
| | - Menyhárt B Sárosi
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig Linnéstrasse 2 04103 Leipzig Germany
| | - Jindřich Fanfrlík
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo nám. 2, CZ-166 10 Praha 6 Czech Republic
| | - Michal Straka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo nám. 2, CZ-166 10 Praha 6 Czech Republic
| | - Josef Holub
- Institute of Inorganic Chemistry of the Czech Academy of Sciences CZ-250 68 Husinec-Řež Czech Republic
| | - Michael L McKee
- Department of Chemistry and Biochemistry, Auburn University Auburn AL 36849 USA
| | - Drahomír Hnyk
- Institute of Inorganic Chemistry of the Czech Academy of Sciences CZ-250 68 Husinec-Řež Czech Republic
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Keller W, Hofmann M, Sárosi MB, Fanfrlík J, Hnyk D. Reactivity of Perhalogenated Octahedral Phospha- and Arsaboranes toward THF: A Joint Experimental/Computational Study. Inorg Chem 2022; 61:16565-16572. [PMID: 36229410 DOI: 10.1021/acs.inorgchem.2c00971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactions of the perhalogenated polyhedral pnictogenaboranes closo-1,2-Pn2B4Hal4 (Pn = P, As; Hal = Cl, Br) with Lewis bases are presently being studied with a focus on rationalizing the sites of nucleophilic attacks on clusters bearing σ-holes. These σ-holes are localized both on pnictogens and, for Hal = Br, on bromine atoms, as revealed by electrostatic potential (ESP) and intrinsic bond orbital (IBO) analyses. Surprisingly, the attack of the cyclic ether THF on closo-1,2-Pn2B4Br4 does not occur on the site with the largest positive partial charge, centered in the middle of the pnictogen-pnictogen vector. Instead, presumably promoted by the positivated bromine substituents, THF inserts into the boron-bromine bonds of the negatively charged boron atoms opposite to the pnictogen atoms to form 4-(4-bromobut-1-oxy)-closo-1,2-Pn2B4Br3 (1-PB and 1-AsB) and 4,6-(4-bromobut-1-oxy)2-closo-1,2-Pn2B4Br2 (2-PB and 2-AsB). 11B and 31P chemical shift computations at various levels support the assignments of the signals, which reflect the correctness of the molecular geometries in solutions. The Lewis-acidic perchlorinated analogues closo-1,2-P2B4Cl4, closo-1,2-As2B4Cl4, and the mixed closo-1,2-AsPB4Cl4 bear negative charges. These negative charges are revealed by the Vs,max values when computing the electrostatic potentials both on the boron and the chlorine atoms. Due to this negative charge, the analogues do not react with THF unless they are heated above 66 °C, where they slowly decompose to borate esters B(OR)3 without the formation of concrete intermediates. The evaluation of 31P NMR data of 1-PB has allowed the experimental determination of the coupling constant 1J(31P(1), 31P(2)) = |143| Hz in a closo-diphosphaborane for the first time, which agrees well with the computed value of -178 Hz. The pioneering joint experimental vs computational interpretation of 31P NMR spectra in the area of boron cluster chemistry was decisive for the structural characterization of 1-PB and 2-PB.
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Affiliation(s)
- Willi Keller
- Institut für Chemie, Universität Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany
| | - Matthias Hofmann
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Menyhárt-Botond Sárosi
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, 04103 Leipzig, Germany
| | - Jindřich Fanfrlík
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Praha 6, Czech Republic
| | - Drahomír Hnyk
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, 250 68 Husinec-Řež, Czech Republic
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Definition of the Pnictogen Bond: A Perspective. INORGANICS 2022. [DOI: 10.3390/inorganics10100149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This article proposes a definition for the term “pnictogen bond” and lists its donors, acceptors, and characteristic features. These may be invoked to identify this specific subset of the inter- and intramolecular interactions formed by elements of Group 15 which possess an electrophilic site in a molecular entity.
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Varadwaj A, Varadwaj PR, Marques HM, Yamashita K. The Stibium Bond or the Antimony-Centered Pnictogen Bond: The Covalently Bound Antimony Atom in Molecular Entities in Crystal Lattices as a Pnictogen Bond Donor. Int J Mol Sci 2022; 23:4674. [PMID: 35563065 PMCID: PMC9099767 DOI: 10.3390/ijms23094674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/16/2022] [Accepted: 04/18/2022] [Indexed: 12/04/2022] Open
Abstract
A stibium bond, i.e., a non-covalent interaction formed by covalently or coordinately bound antimony, occurs in chemical systems when there is evidence of a net attractive interaction between the electrophilic region associated with an antimony atom and a nucleophile in another, or the same molecular entity. This is a pnictogen bond and are likely formed by the elements of the pnictogen family, Group 15, of the periodic table, and is an inter- or intra-molecular non-covalent interaction. This overview describes a set of illustrative crystal systems that were stabilized (at least partially) by means of stibium bonds, together with other non-covalent interactions (such as hydrogen bonds and halogen bonds), retrieved from either the Cambridge Structure Database (CSD) or the Inorganic Crystal Structure Database (ICSD). We demonstrate that these databases contain hundreds of crystal structures of various dimensions in which covalently or coordinately bound antimony atoms in molecular entities feature positive sites that productively interact with various Lewis bases containing O, N, F, Cl, Br, and I atoms in the same or different molecular entities, leading to the formation of stibium bonds, and hence, being partially responsible for the stability of the crystals. The geometric features, pro-molecular charge density isosurface topologies, and extrema of the molecular electrostatic potential model were collectively examined in some instances to illustrate the presence of Sb-centered pnictogen bonding in the representative crystal systems considered.
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Affiliation(s)
- Arpita Varadwaj
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan; (A.V.); (K.Y.)
| | - Pradeep R. Varadwaj
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan; (A.V.); (K.Y.)
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa;
| | - Helder M. Marques
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa;
| | - Koichi Yamashita
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan; (A.V.); (K.Y.)
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Isamura BK, Lobb KA, Muya JT. Regioselectivity, chemical bonding and physical nature of the interaction between imidazole and XAHs (X=H, F, Cl, Br, CH3, and A=S, Se, Te). Mol Phys 2022. [DOI: 10.1080/00268976.2022.2026511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Bienfait Kabuyaya Isamura
- Department of Chemistry, Rhodes University, Makhanda, South Africa
- Department of Chemistry, Faculty of Sciences, University of Kinshasa, XI, Kinshasa, DR Congo
- Research Center for Theoretical Chemistry and Physics in Central Africa, Faculty of Science, University of Kinshasa, Kinshasa, DR Congo
| | - Kevin Alan Lobb
- Department of Chemistry, Rhodes University, Makhanda, South Africa
- Research Unit in Bioinformatics (RUBi), Rhodes University, Makhanda, South Africa
| | - Jules Tshishimbi Muya
- Department of Chemistry, Faculty of Sciences, University of Kinshasa, XI, Kinshasa, DR Congo
- Research Center for Theoretical Chemistry and Physics in Central Africa, Faculty of Science, University of Kinshasa, Kinshasa, DR Congo
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Holub J, Růžička A, Růžičková Z, Fanfrlík J, Hnyk D, Štíbr B. Electrophilic Methylation of Decaborane(14): Selective Synthesis of Tetramethylated and Heptamethylated Decaboranes and Their Conjugated Bases. Inorg Chem 2020; 59:10540-10547. [DOI: 10.1021/acs.inorgchem.0c00917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Josef Holub
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež 250 68, Czech Republic
| | - Aleš Růžička
- Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10, Czech Republic
| | - Zdeňka Růžičková
- Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10, Czech Republic
| | - Jindřich Fanfrlík
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, Praha 6 166 10, Czech Republic
| | - Drahomír Hnyk
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež 250 68, Czech Republic
| | - Bohumil Štíbr
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež 250 68, Czech Republic
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Chalcogen Bonding due to the Exo-Substitution of Icosahedral Dicarbaborane. Molecules 2019; 24:molecules24142657. [PMID: 31340435 PMCID: PMC6680755 DOI: 10.3390/molecules24142657] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 11/17/2022] Open
Abstract
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.
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