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Nguyen L, Aquino J, Mao C, Tavassol H. Proton transfer and regulation across chemical interfaces by small-molecule assemblies. Chemistry 2024; 30:e202302396. [PMID: 38224209 DOI: 10.1002/chem.202302396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Indexed: 01/16/2024]
Abstract
We report on measurements and control of proton gradient across interfaces of water and dichloroethane. Such interfaces are interesting as mimics of biological membranes. We use impedance spectroscopy to quantify interfacial proton gradient and identify proton transfer modes. We quantify proton movement using reciprocal of time constant (τ-1 ) acquired from electrochemical impedance modeling. We show that proton gradient across interfaces of water/dichloroethane and τ-1 correlate with the aqueous phase pH, changing from ca. 1 s-1 at pH 1 to 0.2 s-1 at pH 7. τ-1 changes in the presence of proton shuttling fat-soluble molecules. Dinitrophenol acts as a pH activated proton coupler which is active at around neutral pH and inert at pH <4. However, quinone type cofactors change the interfacial proton transport when activated by redox reactions with ferrocene type molecules, such as decamethyl ferrocence (DMFc). Quinone type cofactors show distinct features in their impedance response assigned to a proton coupled electron transfer (PCET) process, different from the uncoupled proton transfer activity of dinitrophenol. The observed PCET reaction significantly changes τ-1 . We use τ-1 as a proton transport descriptor. In particular, CoQ10 -DMFc shows a τ-1 of 3.5 s-1 at pH 7, indicating how small-molecule assemblies change proton availability.
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Affiliation(s)
- Lynn Nguyen
- Department of Chemistry and Biochemistry, California State University, Long Beach, Long Beach, CA, United States
| | - Joseline Aquino
- Department of Chemistry and Biochemistry, California State University, Long Beach, Long Beach, CA, United States
| | - Cindy Mao
- Department of Chemistry and Biochemistry, California State University, Long Beach, Long Beach, CA, United States
| | - Hadi Tavassol
- Department of Chemistry and Biochemistry, California State University, Long Beach, Long Beach, CA, United States
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Interaction of Vinyl-Type Carbocations, C 3H 5+ and C 4H 7+ with Molecules of Water, Alcohols, and Acetone. Molecules 2023; 28:molecules28031146. [PMID: 36770812 PMCID: PMC9921539 DOI: 10.3390/molecules28031146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
X-ray diffraction analysis and IR spectroscopy were used to study the products of the interaction of vinyl cations C3H5+ and C4H7+ (Cat+) (as salts of carborane anion CHB11Cl11-) with basic molecules of water, alcohols, and acetone that can crystallize from solutions in dichloromethane and C6HF5. Interaction with water, as content increased, proceeded via three-stages. (1) adduct Cat+·OH2 forms in which H2O binds (through the O atom) to the C=C+ bond of the cation with the same strength as seen in the binding to Na in Na(H2O)6+. (2) H+ is transferred from cation Cat+·OH2 to a water molecule forming H3O+ and alcohol molecules (L) having the CH=CHOH entity. The O- atom of alcohols is attached to the H atom of the C=C+-H moiety of Cat+ thereby forming a very strong asymmetric H-bond, (C=)C+-H⋅⋅⋅O. (3) Finally all vinyl cations are converted into alcohol molecule L and H3O+ cations, yielding proton disolvates L-H+-L with a symmetric very strong H-bond. When an acetone molecule (Ac) interacts with Cat+, H+ is transferred to Ac giving rise to a reactive carbene and proton disolvate Ac-H+-Ac. Thus, the alleged high reactivity of vinyl cations seems to be an exaggeration.
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Sofronov OO, Bakker HJ. Nature of hydrated proton vibrations revealed by nonlinear spectroscopy of acid water nanodroplets. Phys Chem Chem Phys 2020; 22:21334-21339. [PMID: 32936152 DOI: 10.1039/d0cp03137b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We use polarization-resolved femtosecond pump-probe spectroscopy to investigate the vibrations of hydrated protons in anionic (AOT) and cationic (CTAB/hexanol) reverse micelles in the frequency range 2000-3500 cm-1. For small AOT micelles the dominant proton hydration structure consists of H3O+ with two OH groups donating hydrogen bonds to water molecules, and one OH group donating a weaker hydrogen bond to sulfonate. For cationic reverse micelles, we find that the absorption at frequencies >2500 cm-1 is dominated by asymmetric proton-hydration structures in which one of the OH groups of H3O+ is more weakly hydrogen-bonded to water than the other two OH groups.
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Ikeda K, Hori Y, Mahyuddin MH, Shiota Y, Staykov A, Matsumoto T, Yoshizawa K, Ogo S. Dual Catalytic Cycle of H2 and H2O Oxidations by a Half-Sandwich Iridium Complex: A Theoretical Study. Inorg Chem 2019; 58:7274-7284. [DOI: 10.1021/acs.inorgchem.9b00307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Kei Ikeda
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Yuta Hori
- Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | | | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Aleksandar Staykov
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
| | - Takahiro Matsumoto
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
- Center for Small Molecule Energy, Kyushu University, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Seiji Ogo
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
- Center for Small Molecule Energy, Kyushu University, Fukuoka 819-0395, Japan
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Chang Y, Zhang N, Yang Y, Du J, Fan X, Tao C. Time-periodic oscillation reaction in an organic-solvent dominated electrolyte. Phys Chem Chem Phys 2017; 19:27643-27650. [PMID: 28983548 DOI: 10.1039/c7cp05414a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-periodic phenomena widely exist in natural life sustaining systems but are rarely reported in highly efficient artificial electrochemical energy-harvesting systems. Herein, we observed for the first time the periodic oscillation reaction in organic-solvent dominated electrolytes that could be also derived from some electrochemical energy harvesting cells. Owing to different reaction activity and acidity in the organic solvent, the oscillation reaction could occur under milder pH conditions and exhibit better durability. Its influence on electric output and related differences from an aqueous B-Z reaction are discussed from a mechanism point of view. Our findings may contribute to smart self-oscillation materials and new strategies for highly efficient long-term energy harvesting.
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Affiliation(s)
- Yu Chang
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, P. R. China.
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7
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Vener MV, Chernyshov IY, Rykounov AA, Filarowski A. Structural and spectroscopic features of proton hydrates in the crystalline state. Solid-state DFT study on HCl and triflic acid hydrates. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1380860] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- M. V. Vener
- Quantum Chemistry Department, Mendeleev University of Chemical Technology, Moscow, Russia
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - I. Yu. Chernyshov
- Quantum Chemistry Department, Mendeleev University of Chemical Technology, Moscow, Russia
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - A. A. Rykounov
- Theoretical Department, Russian Federal Nuclear Center – All-Russian Research Institute of Technical Physics (RFNC-VNIITF), Snezhinsk, Russia
| | - A. Filarowski
- Faculty of Chemistry, University of Wrocław, Wrocław, Poland
- Department of Physics, Industrial University of Tyumen, Tyumen, Russia
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8
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Podlipskaya TY, Bulavchenko AI. Structure and location of proton hydrates in Triton N-42 reverse micelles during injection solubilization of HCl solutions. J STRUCT CHEM+ 2016. [DOI: 10.1134/s0022476616080102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Verma S, Aute S, Das A, Ghosh HN. Proton-Coupled Electron Transfer in a Hydrogen-Bonded Charge-Transfer Complex. J Phys Chem B 2016; 120:10780-10785. [DOI: 10.1021/acs.jpcb.6b06032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sandeep Verma
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Sunil Aute
- CSIR-National Chemical Laboratory, Pune 411008, India
| | - Amitava Das
- CSIR-National Chemical Laboratory, Pune 411008, India
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, India
| | - Hirendra N. Ghosh
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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Park SY, Kim TG, Ajitha MJ, Kwac K, Lee YM, Kim H, Jung Y, Kwon OH. The critical size of hydrogen-bonded alcohol clusters as effective Brønsted bases in solutions. Phys Chem Chem Phys 2016; 18:24880-9. [PMID: 27337993 DOI: 10.1039/c6cp01650b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The alkyl oxonium ion, which is a protonated alcohol, has long been proposed as a key reaction intermediate in alcohol dehydration. Nonetheless, the dynamics and structure of this simple but important intermediate species have not been adequately examined due to the transient nature of the oxonium ion. Here, we devised a model system for the key step in the alcohol dehydration reaction, in which a photoacid transfers a proton to alcohols of different basicity in the acetonitrile solvent. Using time-resolved spectroscopy and computation, we have found that the linkage of at least two alcohol molecules via hydrogen bonding is critical for their enhanced reactivity and extraction of the proton from the acid. This finding addresses the cooperative role of the simplest organic protic compounds, namely alcohols, in nonaqueous acid-base reactions.
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Affiliation(s)
- Sun-Young Park
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
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11
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Agmon N, Bakker HJ, Campen RK, Henchman RH, Pohl P, Roke S, Thämer M, Hassanali A. Protons and Hydroxide Ions in Aqueous Systems. Chem Rev 2016; 116:7642-72. [PMID: 27314430 DOI: 10.1021/acs.chemrev.5b00736] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the structure and dynamics of water's constituent ions, proton and hydroxide, has been a subject of numerous experimental and theoretical studies over the last century. Besides their obvious importance in acid-base chemistry, these ions play an important role in numerous applications ranging from enzyme catalysis to environmental chemistry. Despite a long history of research, many fundamental issues regarding their properties continue to be an active area of research. Here, we provide a review of the experimental and theoretical advances made in the last several decades in understanding the structure, dynamics, and transport of the proton and hydroxide ions in different aqueous environments, ranging from water clusters to the bulk liquid and its interfaces with hydrophobic surfaces. The propensity of these ions to accumulate at hydrophobic surfaces has been a subject of intense debate, and we highlight the open issues and challenges in this area. Biological applications reviewed include proton transport along the hydration layer of various membranes and through channel proteins, problems that are at the core of cellular bioenergetics.
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Affiliation(s)
- Noam Agmon
- The Fritz Haber Research Center, Institute of Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Huib J Bakker
- FOM Institute AMOLF , Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - R Kramer Campen
- Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - Richard H Henchman
- Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Peter Pohl
- Johannes Kepler University Linz , Institute of Biophysics, Gruberstrasse 40, 4020 Linz, Austria
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Material Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015, Lausanne, Switzerland
| | - Martin Thämer
- Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany.,Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Ali Hassanali
- CMSP Section, The Abdus Salaam International Center for Theoretical Physics , I-34151 Trieste, Italy
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12
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Park SY, Lee YM, Kwac K, Jung Y, Kwon OH. Alcohol Dimer is Requisite to Form an Alkyl Oxonium Ion in the Proton Transfer of a Strong (Photo)Acid to Alcohol. Chemistry 2016; 22:4340-4. [DOI: 10.1002/chem.201503948] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Sun-Young Park
- Center for Soft and Living Matter; Institute for Basic Science (IBS); Ulsan 689-798 Republic of Korea
| | - Young Min Lee
- Department of Chemistry; Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Republic of Korea
| | - Kijeong Kwac
- Graduate School of Energy, Environment, Water and Sustainability (EEWS); Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Yousung Jung
- Graduate School of Energy, Environment, Water and Sustainability (EEWS); Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Oh-Hoon Kwon
- Center for Soft and Living Matter; Institute for Basic Science (IBS); Ulsan 689-798 Republic of Korea
- Department of Chemistry; Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Republic of Korea
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Wood MR, Lalancette RA, Bernal I. Crystallographic investigations of select cathinones: emerging illicit street drugs known as `bath salts'. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2015; 71:32-8. [DOI: 10.1107/s2053229614025637] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/23/2014] [Indexed: 11/10/2022]
Abstract
The name `bath salts', for an emerging class of synthetic cathinones, is derived from an attempt to evade prosecution and law enforcement. These are truly illicit drugs that have psychoactive CNS (central nervous system) stimulant effects and they have seen a rise in abuse as recreational drugs in the last few years since first having been seen in Japan in 2006. The ease of synthesis and modification of specific functional groups of the parent cathinone make these drugs particularly difficult to regulate. MDPV (3,4-methylenedioxypyrovalerone) is commonly encountered as its hydrochloride salt (C16H21NO3·HCl), in either the hydrated or the anhydrous forms. This `bath salt' has various names in the US,e.g.`Super Coke', `Cloud Nine', and `Ivory Wave', to name just a few. We report here the structures of two forms of the HCl salt, one as a mixed bromide/chloride salt, C16H22NO3+·0.343Br−·0.657Cl−[systematic name: 1-(benzo[d][1,3]dioxol-5-yl)-2-(pyrrolidin-1-ium-1-yl)pentan-1-one bromide/chloride (0.343/0.657)], and the other with the H7O3+cation, as well as the HCl counter-ion [systematic name: hydroxonium 1-(benzo[d][1,3]dioxol-5-yl)-2-(pyrrolidin-1-ium-1-yl)pentan-1-one dichloride, H7O3+·C16H22NO3+·2Cl−]. This is one of a very few structures (11 to be exact) in which we have a new example of a precisely determined hydroxonium cation. During the course of researching the clandestine manufacture of MDPV, we were surprised by the fact that a common precursor of this illicit stimulant is known to be the fragrant species piperonal, which is present in the fragrances of orchids, most particularly in the case of the vanilla orchid. We found that MDPV can be made by a Grignard reaction of this heliotropin. This may also explain the unexpected appearance of the bromide counter-ion in some of the salts we encountered (C16H21NO3·HBr), one of which is presented here [systematic name: 1-(benzo[d][1,3]dioxol-5-yl)-2-(pyrrolidin-1-ium-1-yl)pentan-1-one bromide, C16H22NO3+·Br−]. Complexation of MDPV with a forensic crystallizing reagent, HAuCl4, yields the tetrachloridoaurate salt of this drug, (C16H22NO3)[AuCl4]. The heavy-metal complexing agent HAuCl4has been used for over a century to identify common quarternary nitrogen-containing drugsviamicroscopic identification. Another street drug, called ethylone (3,4-methylenedioxyethylcathinone), is regularly sold and abused as its hydrochloride salt (C12H15NO3·HCl), and its structure is herein described (systematic name:N-{1-[(benzo[d][1,3]dioxol-5-yl)carbonyl]ethyl}ethanaminium chloride, C12H16NO3+·Cl−). Marketed and sold as a `bath salt', `plant feeder', or `cleaning product', this drug is nothing more than a slight chemical modification of the banned drug methylone (3,4-methylenedioxymethcathinone). As with previously popular synthetic cathinones, the abuse of ethylone has seen a recent increase due to regulatory efforts on previous generations of cathinones that are now banned.
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Chakraborty P, Jana A, Mohanta S. Surprising difference between two closely similar O(phenoxo)2O(ether)2 compartments as hosts for an aquated proton and a novel type of host–guest system. Polyhedron 2014. [DOI: 10.1016/j.poly.2014.03.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Bernal I, Watkins SF. Molecular and supramolecular ionic aggregates HxOyzin organic and organometallic crystalline hydrates. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2014; 70:566-74. [DOI: 10.1107/s2053229614009826] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/01/2014] [Indexed: 11/10/2022]
Abstract
Ionic aggregates of the form HxOyz(z≠ 0) have been characterized during an analysis of 245 crystal structures extracted from the Cambridge Structural Database [Allen (2002).Acta Cryst.B58, 380–388]. A systematic nomenclature is proposed for these species. Three modes of hydrogen bonding are described, characterized in part by the distance between contiguous O atoms: normal (NHB; O...O = 2.6–3.0 Å), charge assisted (CAHB; O...O = 2.5 Å) and molecular (MHB; O...O = 2.4 Å). The three modes are consistent with previous reports, our experimental results, and quantum-chemical-optimized geometries and energetics. No evidence is presented concerning the possible existence or stability of these aggregates in solution. Rather, emphasis is placed on the necessity in crystal structure analysis to develop thoroughly existing hydrogen-bonded networks, ignorance of which can lead to erroneous crystal structure models and other physico-chemical data associated with composition and charge balance.
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Trojánek A, Langmaier J, Kvapilová H, Záliš S, Samec Z. Inhibitory Effect of Water on the Oxygen Reduction Catalyzed by Cobalt(II) Tetraphenylporphyrin. J Phys Chem A 2014; 118:2018-28. [DOI: 10.1021/jp500057x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Antonín Trojánek
- J. Heyrovský Institute
of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Jan Langmaier
- J. Heyrovský Institute
of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Hana Kvapilová
- J. Heyrovský Institute
of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Stanislav Záliš
- J. Heyrovský Institute
of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Zdeněk Samec
- J. Heyrovský Institute
of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
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Douvris C, Michl J. Update 1 of:Chemistry of the Carba-closo-dodecaborate(−) Anion, CB11H12–. Chem Rev 2014; 113:PR179-233. [PMID: 23944158 DOI: 10.1021/cr400059k] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christos Douvris
- Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, 16610 Prague, Czech Republic
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Josef Michl
- Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, 16610 Prague, Czech Republic
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
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Halogenido ligand exchange synthesis, spectroscopic properties and thermal behaviour of the inorganic–organic hydrogen-bonded network solid [4,4′-H2bipy][H7O3][RhBr6] containing discrete and weakly associated [H7O3]+ ions. Polyhedron 2014. [DOI: 10.1016/j.poly.2013.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Molčanov K, Stare J, Vener MV, Kojić-Prodić B, Mali G, Grdadolnik J, Mohaček-Grošev V. Nitranilic acid hexahydrate, a novel benchmark system of the Zundel cation in an intrinsically asymmetric environment: spectroscopic features and hydrogen bond dynamics characterised by experimental and theoretical methods. Phys Chem Chem Phys 2013; 16:998-1007. [PMID: 24281720 DOI: 10.1039/c3cp54026j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Nitranilic acid (2,5-dihydroxy-3,6-dinitro-2,5-cyclohexadiene-1,4-dione) as a strong dibasic acid in acidic aqueous media creates the Zundel cation, H5O2(+). The structural unit in a crystal comprises (H5O2)2(+) (2,5-dihydroxy-3,6-dinitro-1,4-benzoquinonate)(2-) dihydrate where the Zundel cation reveals no symmetry, being an ideal case for studying proton dynamics and its stability. The Zundel cation and proton transfer dynamics are studied by variable-temperature X-ray diffraction, IR and solid-state NMR spectroscopy, and various quantum chemical methods, including periodic DFT calculations, ab initio molecular dynamics simulation, and quantization of nuclear motion along three fully coupled internal coordinates. The Zundel cation features a short H-bond with the O···O distance of 2.433(2) Å with an asymmetric placement of hydrogen. The proton potential is of a single well type and, due to the non-symmetric surroundings, of asymmetric shape. The formation of the Zundel cation is facilitated by the electronegative NO2 groups. The employed spectroscopic techniques supported by calculations confirm the presence of a short H-bond with a complex proton dynamics.
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Maiorov VD, Kislina IS, Rykounov AA, Vener MV. The structure and vibrational features of proton disolvates in water-ethanol solutions of HCl: the combined spectroscopic and theoretical study. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3251] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Vladimir D. Maiorov
- Semenov Institute of Chemical Physics; Russian Academy of Sciences; Moscow Russia
| | - Irina S. Kislina
- Semenov Institute of Chemical Physics; Russian Academy of Sciences; Moscow Russia
| | - Alexey A. Rykounov
- Snezhinsk Physics and Technology Institute; National Research Nuclear University MEPhI; Snezhinsk Russia
| | - Mikhail V. Vener
- Quantum Chemistry Department; Mendeleev University of Chemical Technology; Moscow Russia
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Abstract
Recent research has taught us that most protonated species are decidedly not well represented by a simple proton addition. What is the actual nature of the hydrogen ion (the "proton") when H(+), HA, H2A(+), and so forth are written in formulas, chemical equations, and acid catalyzed reactions? In condensed media, H(+) must be solvated and is nearly always dicoordinate, as illustrated by isolable bisdiethyletherate salts having H(OEt2)2(+) cations and weakly coordinating anions. Even carbocations such as protonated alkenes have significant C-H···anion hydrogen bonding that gives the active protons two-coordinate character. Hydrogen bonding is everywhere, particularly when acids are involved. In contrast to the normal, asymmetric O-H···O hydrogen bonding found in water, ice, and proteins, short, strong, low-barrier (SSLB) H-bonding commonly appears when strong acids are present. Unusually low frequency IR νOHO bands are a good indicator of SSLB H-bonds, and curiously, bands associated with group vibrations near H(+) in low-barrier H-bonding often disappear from the IR spectrum. Writing H3O(+) (the Eigen ion), as often appears in textbooks, might seem more realistic than H(+) for an ionized acid in water. However, this, too, is an unrealistic description of H(aq)(+). The dihydrated H(+) in the H5O2(+) cation (the Zundel ion) gets somewhat closer but still fails to rationalize all the experimental and computational data on H(aq)(+). Researchers do not understand the broad swath of IR absorption from H(aq)(+), known as the "continuous broad absorption" (cba). Theory has not reproduced the cba, but it appears to be the signature of delocalized protons whose motion is faster than the IR time scale. What does this mean for reaction mechanisms involving H(aq)(+)? For the past decade, the carborane acid H(CHB11Cl11) has been the strongest known Brønsted acid. (It is now surpassed by the fluorinated analogue H(CHB11F11).) Carborane acids are strong enough to protonate alkanes at room temperature, giving H2 and carbocations. They protonate chloroalkanes to give dialkylchloronium ions, which decay to carbocations. By partially protonating an oxonium cation, they get as close to the fabled H4O(2+) ion as can be achieved outside of a computer.
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Affiliation(s)
- Christopher A. Reed
- Department of Chemistry, University of California, Riverside, California 92521, USA
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Wright JH, Kefalidis CE, Tham FS, Maron L, Lavallo V. Click-Like Reactions with the Inert HCB11Cl11– Anion Lead to Carborane-Fused Heterocycles with Unusual Aromatic Character. Inorg Chem 2013; 52:6223-9. [DOI: 10.1021/ic400786a] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- James H. Wright
- Department of Chemistry, University of California Riverside, Riverside, California 92521,
United States
| | - Christos E. Kefalidis
- Department of Chemistry, CNRS & INSA, UPS, LPCNO, Université de Toulouse, 135 Avenue de Rangueil, F-31077, Toulouse France
| | - Fook S. Tham
- Department of Chemistry, University of California Riverside, Riverside, California 92521,
United States
| | - Laurent Maron
- Department of Chemistry, CNRS & INSA, UPS, LPCNO, Université de Toulouse, 135 Avenue de Rangueil, F-31077, Toulouse France
| | - Vincent Lavallo
- Department of Chemistry, University of California Riverside, Riverside, California 92521,
United States
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Chen JJ, Chen W, He H, Li DB, Li WW, Xiong L, Yu HQ. Manipulation of microbial extracellular electron transfer by changing molecular structure of phenazine-type redox mediators. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:1033-1039. [PMID: 23244024 DOI: 10.1021/es304189t] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Phenazines, as a type of electron shuttle, are involved in various biological processes to facilitate microbial energy metabolism and electron transfer. They constitute a large group of nitrogen-containing heterocyclic compounds, which can be produced by a diverse range of bacteria or by artificial synthesis. They vary significantly in their properties, depending mainly on the nature and position of substitutent group. Thus, it is of great interest to find out the most favorable substituent type and molecular structure of phenazines for electron transfer routes. Here, the impacts of the substituent group on the reduction potentials of phenazine-type redox mediators in aqueous solution were investigated by quantum chemical calculations, and the calculation results were further validated with experimental data. The results show that the reaction free energy was substantially affected by the location of substituent groups on the phenazine molecule and the protonated water clusters. For the main proton addition process, the phenazines substituted with electron-donating groups and those with electron-withdrawing groups interacted with different protonated water clusters, attributed to the proximity effect of water molecules on proton transfer. Thus, high energy conversion efficiency could be achieved by controlling electron flow route with appropriate substituted phenazines to reduce the biological energy acquisition. This study provides useful information for designing efficient redox mediators to promote electron transfer between microbes and terminal acceptors, which are essential to bioenergy recovery from wastes and environmental bioremediation.
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Affiliation(s)
- Jie-Jie Chen
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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Jana A, Weyhermüller T, Mohanta S. Metal complex analogues of crown ethers as the preorganized motif to stabilize aquated proton in solid state. CrystEngComm 2013. [DOI: 10.1039/c3ce27075k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Carboranes as model hypercarbon systems; structural and bonding patterns in selected isoelectronic closo-borane and carborane systems; [BnHn]2−, [1-CBn−1Hn]− and 1,n-C2Bn−2Hn (n = 5, 6, 7, 10 or 12). J Organomet Chem 2012. [DOI: 10.1016/j.jorganchem.2012.07.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Suarez SA, Foi A, Eady S, Larsen A, Doctorovich F. N-Butylpyridinium undecachlorocarbadodecaborate and comparison with similar compounds. Acta Crystallogr C 2011; 67:o417-20. [DOI: 10.1107/s0108270111035165] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 08/29/2011] [Indexed: 11/11/2022] Open
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28
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Kong S, Borissova AO, Lesnichin SB, Hartl M, Daemen LL, Eckert J, Antipin MY, Shenderovich IG. Geometry and spectral properties of the protonated homodimer of pyridine in the liquid and solid states. A combined NMR, X-ray diffraction and inelastic neutron scattering study. J Phys Chem A 2011; 115:8041-8. [PMID: 21644583 DOI: 10.1021/jp203543g] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structure and spectral signatures of the protonated homodimer of pyridine in its complex with a poorly coordinating anion have been studied in solution in CDF(3)/CDClF(2) down to 120 K and in a single crystal. In both phases, the hydrogen bond is asymmetric. In the solution, the proton is involved in a fast reversible transfer that determines the multiplicity of NMR signals and the sign of the primary H/D isotope effect of --0.95 ppm. The proton resonates at 21.73 ppm that is above any value reported in the past and is indicative of a very short hydrogen bond. By combining X-ray diffraction analysis with model computations, the position of the proton in the crystal has been defined as d(N-H) = 1.123 Å and d(H···N) = 1.532 Å. The same distances have been estimated using a (15)N NMR correlation. The frequency of the protonic out-of-plane bending mode is 822 cm(-1) in agreement with Novak's correlation.
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Affiliation(s)
- S Kong
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
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Hayes RL, Paddison SJ, Tuckerman ME. Proton transport in triflic acid pentahydrate studied via ab initio path integral molecular dynamics. J Phys Chem A 2011; 115:6112-24. [PMID: 21434672 DOI: 10.1021/jp110953a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Trifluoromethanesulfonic acid hydrates provide a well-defined system to study proton dissociation and transport in perfluorosulfonic acid membranes, typically used as the electrolyte in hydrogen fuel cells, in the limit of minimal water. The triflic acid pentahydrate crystal (CF(3)SO(3)H·5H(2)O) is sufficiently aqueous that it contains an extended three-dimensional water network. Despite it being extended, however, long-range proton transport along the network is structurally unfavorable and would require considerable rearrangement. Nevertheless, the triflic acid pentahydrate crystal system can provide a clear picture of the preferred locations of local protonic defects in the water network, which provides insights about related structures in the disordered, low-hydration environment of perfluorosulfonic acid membranes. Ab initio molecular dynamics simulations reveal that the proton defect is most likely to transfer to the closest water that has the expected presolvation and only contains water in its first solvation shell. Unlike the tetrahydrate of triflic acid (CF(3)SO(3)H·4H(2)O), there is no evidence of the proton preferentially transferring to a water molecule bridging two of the sulfonate groups. However, this could be an artifact of the crystal structure since the only such water molecule is separated from the proton by long O-O distances. Hydrogen bonding criteria, using the two-dimensional potential of mean force, are extracted. Radial distribution functions, free energy profiles, radii of gyration, and the root-mean-square displacement computed from ab initio path integral molecular dynamics simulations reveal that quantum effects do significantly extend the size of the protonic defect and increase the frequency of proton transfer events by nearly 15%. The calculated IR spectra confirm that the dominant protonic defect mostly exists as an Eigen cation but contains some Zundel ion characteristics. Chain lengths and ring sizes determined from the hydrogen bond network, counted using graph theory techniques, are only moderately sensitive to quantum effects. Deliberately introducing a structural defect into the native crystal yields a protonic defect with one hydrogen bond to a sulfonate group that was found to be metastable for at least 10 ps.
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Affiliation(s)
- Robin L Hayes
- Department of Chemistry, New York University, New York, New York, USA
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Kalish NBM, Shandalov E, Kharlanov V, Pines D, Pines E. Apparent stoichiometry of water in proton hydration and proton dehydration reactions in CH3CN/H2O solutions. J Phys Chem A 2011; 115:4063-75. [PMID: 21417385 DOI: 10.1021/jp110873t] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gradual solvation of protons by water is observed in liquids by mixing strong mineral acids with various amounts of water in acetonitrile solutions, a process which promotes rapid dissociation of the acids in these solutions. The stoichiometry of the reaction XH(+) + n(H(2)O) = X + (H(2)O)(n)H(+) was studied for strong mineral acids (negatively charged X, X = ClO(4)¯, Cl¯, Br¯, I¯, CF(3)SO(3)¯) and for strong cationic acids (uncharged X, X = R*NH(2), H(2)O). We have found by direct quantitative analysis preference of n = 2 over n = 1 for both groups of proton transfer reactions at relatively low water concentrations in acetonitrile. At high water concentrations, we have found that larger water solvates must also be involved in the solvation of the proton while the spectral features already observed for n = 2, H(+)(H(2)O)(2), remain almost unchanged at large n values up to at least 10 M of water.
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Min SK, Park M, Singh NJ, Lee HM, Lee EC, Kim KS, Lagutschenkov A, Niedner-Schatteburg G. Chiral transformation in protonated and deprotonated adipic acids through multistep internal proton transfer. Chemistry 2010; 16:10373-9. [PMID: 20652911 DOI: 10.1002/chem.200903355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Protonated and deprotonated adipic acids (PAA: HOOC-(CH(2))(4)--COOH(2) (+) and DAA: HOOC-(CH(2))(4)-COO(-)) have a charged hydrogen bond under the influence of steric constraint due to the molecular skeleton of a circular ring. Despite the similarity between PAA and DAA, it is surprising that the lowest energy structure of PAA is predicted to have (H(2)O...H...OH(2))(+) Zundel-like symmetric hydrogen bonding, whereas that of DAA has H(3)O(+) Eigen-like asymmetric hydrogen bonding. The energy profiles show that direct proton transfer between mirror image structures is unfavorable. Instead, the chiral transformation is possible by subsequent backbone twistings through stepwise proton transfer along multistep intermediate structures, which are Zundel-like ions for PAA and Eigen-like ions for DAA. This type of chiral transformation by multistep intramolecular proton transfers is unprecedented. Several prominent OH...O short hydrogen-bond stretching peaks are predicted in the range of 1000-1700 cm(-1) in the Car-Parrinello molecular dynamics (CPMD) simulations, which show distinctive signatures different from ordinary hydrogen-bond peaks. The O-H-O stretching peaks in the range of 1800-2700 cm(-1) become insignificant above around 150 K and are almost washed out at about 300 K.
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Affiliation(s)
- Seung Kyu Min
- Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, 790-784 Pohang, South Korea
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Stoyanov ES, Stoyanova IV, Reed CA. The structure of the hydrogen ion (H(aq)+) in water. J Am Chem Soc 2010; 132:1484-5. [PMID: 20078058 DOI: 10.1021/ja9101826] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The hydrogen ion in water, H(aq)(+), is a unique H(13)O(6)(+) entity that defines the boundary of positive-charge delocalization. Its central unit is neither a C(3v) H(3)O(+) Eigen-type ion nor a typical H(5)O(2)(+) Zundel-type ion. IR spectroscopy indicates that the H(13)O(6)(+) ion has an unexpectedly long central O...O separation (>>2.43 A), showing that in comparison with the gas and solid phases, the environment of liquid water is uniquely proficient in delocalizing positive charge. These results will change the description of H(aq)(+) in textbooks of chemistry, and a more extensive delocalization of positive charge may need to be incorporated into descriptions of mechanisms of aqueous proton transport.
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Affiliation(s)
- Evgenii S Stoyanov
- Department of Chemistry, University of California, Riverside, California 92521-0403, USA
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Stoyanov ES, Stoyanova IV, Tham FS, Reed CA. H(aq)+ structures in proton wires inside nanotubes. J Am Chem Soc 2010; 131:17540-1. [PMID: 19911820 DOI: 10.1021/ja907708g] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrated carborane acid H(CHB(11)I(11)).8H(2)O crystallizes in nanometer-diameter tubes of H(aq)(+) enclosed by walls of carborane anions. Three different types of H(aq)(+) clusters are found in these tubes: a symmetrical H(13)O(6)(+) ion with an unusually elongated Zundel-type H(5)O(2)(+) core, two hydrated H(7)O(3)(+) ions, and an unprecedented H(17)O(8)(+) ion having a nearly square core. All of the H(aq)(+) cations show unexpectedly longer O...O separations than in discrete H(aq)(+) ions, indicating greater delocalization of positive charge. The centrosymmetric H(aq)(+) ions are linked via short H bonds, forming a true one-dimensional proton wire.
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Affiliation(s)
- Evgenii S Stoyanov
- Department of Chemistry, University of California, Riverside, California 92521-0403, USA.
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Hayes RL, Paddison SJ, Tuckerman ME. Proton transport in triflic acid hydrates studied via path integral car-parrinello molecular dynamics. J Phys Chem B 2010; 113:16574-89. [PMID: 19968267 DOI: 10.1021/jp907853p] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The mono-, di-, and tetrahydrates of trifluoromethanesulfonic acid, which contain characteristic H(3)O(+), H(5)O(2)(+), and H(9)O(4)(+) structures, provide model systems for understanding proton transport in materials with high perfluorosulfonic acid density such as perfluorosulfonic acid membranes commonly employed in hydrogen fuel cells. Ab initio molecular dynamics simulations indicate that protons in these solids are predisposed to transfer to the water most strongly bound to sulfonate groups via a Grotthuss-type mechanism, but quickly return to the most solvated defect structure either due to the lack of a nearby species to stabilize the new defect or a preference for the proton to be maximally hydrated. Path integral molecular dynamics of the mono- and dihydrate reveal significant quantum effects that facilitate proton transfer to the "presolvated" water or SO(3)(-) in the first solvation shell and increase the Zundel character of all the defects. These trends are quantified in free energy profiles for each bonding environment. Hydrogen bonding criteria for HOH-OH(2) and HOH-O(3)S are extracted from the two-dimensional potential of mean force. The quantum radial distribution function, radius of gyration, and root-mean-square displacement position correlation function show that the protonic charge is distributed over two or more water molecules. Metastable structural defects with one excess proton shared between two sulfonate groups and another Zundel or Eigen type cation defect are found for the mono- and dihydrate but not for the tetrahydrate crystal. Results for the tetrahydrate native crystal exhibit minor differences at 210 and 250 K. IR spectra are calculated for all native and stable defect structures. Graph theory techniques are used to characterize the chain lengths and ring sizes in the hydrogen bond network. Low conductivities when limited water is present may be attributable to trapping of protons between SO(3)(-) groups and the increased probability that protons transfer to waters bridging two different sulfonate groups.
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Affiliation(s)
- Robin L Hayes
- Department of Chemistry, New York University, New York, USA
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Abstract
For decades, triflic acid, methyl triflate, and trialkylsilyl triflate reagents have served synthetic chemistry well as clean, strong electrophilic sources of H(+), CH(3)(+), and R(3)Si(+), respectively. However, a number of weakly basic substrates are unreactive toward these reagents. In addition, triflate anion can express undesired nucleophilicity toward electrophilically activated substrates. In this Account, we describe methods that replace triflate-based electrophilic reagents with carborane reagents. Using carborane anions of type CHB(11)R(5)X(6)(-) (R = H, Me, X; X = Br, Cl), members of a class of notably inert, weakly nucleophilic anions, significantly increases the electrophilicity of these reagents and shuts down subsequent nucleophilic chemistry of the anion. Thus, H(carborane) acids cleanly protonate benzene, phosphabenzene, C(60), etc., while triflic acid does not. Similarly, CH(3)(carborane) reagents can methylate substrates that are inert to boiling neat methyl triflate, including benzene, phosphabenzenes, phosphazenes, and the pentamethylhydrazinium ion, which forms the dipositive ethane analogue, Me(6)N(2)(2+). Methyl carboranes are also surprisingly effective in abstracting hydride from simple alkanes to give isolable carbocation salts, e.g., t-butyl cation. Trialkylsilyl carborane reagents, R(3)Si(carborane), abstract halides from substrates to produce cations of unprecedented reactivity. For example, fluoride is extracted from freons to form carbocations; chloride is extracted from IrCl(CO)(PPh(3))(2) to form a coordinatively unsaturated iridium cation that undergoes oxidative addition with chlorobenzene at room temperature; and silylation of cyclo-N(3)P(3)Cl(6) produces a catalyst for the polymerization of phosphazenes that functions at room temperature. Although currently too expensive for widespread use, carborane reagents are nevertheless of considerable interest as specialty reagents for making reactive cations and catalysts.
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Affiliation(s)
- Christopher A Reed
- Center for s and p Block Chemistry, Department of Chemistry, University of California, Riverside, California 92521, USA.
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Vener MV, Librovich NB. The structure and vibrational spectra of proton hydrates: as a simplest stable ion. INT REV PHYS CHEM 2009. [DOI: 10.1080/01442350903079955] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
Acid remarks: The anhydrous diprotic boron acids H(2)(B(12)X(12)) (X = Cl, Br; see picture, B orange, X green) are the first examples of diprotic superacids and may be the strongest acids yet isolated. Both protons protonate benzene to give benzenium ion salts that are stable at room temperature. These acids owe their existence to the stability of the icosahedral B(12) cluster with its dinegative charge buried beneath a layer of halide substituents.
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Affiliation(s)
- Amy Avelar
- Center for S and P Block Chemistry, Department of Chemistry University of California, Riverside, CA 92521-0403 (USA)
| | - Fook S. Tham
- Center for S and P Block Chemistry, Department of Chemistry University of California, Riverside, CA 92521-0403 (USA)
| | - Christopher A. Reed
- Center for S and P Block Chemistry, Department of Chemistry University of California, Riverside, CA 92521-0403 (USA)
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