Ralf Haiges

University of Southern California

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Karl O. Christe

University of Southern California

352

G. K. Surya Prakash

Saveetha University

Jerry A. Boatz

Edwards Air Force Base

David A. Dixon

University of Alabama

Mark E. Thompson

University of Southern California

Peter I. Djurovich

University of Southern California

Thorsten Schroer

University of Southern California

Piyush Deokar

University of Southern California

Monica Vasiliu

University of Alabama

Thomas Saal

University of Southern California

Cooperative Institutions

University of Southern California

193

Southern California University for Professional Studies

Los Angeles City College

California Institute of Technology

Chinese Academy of Sciences

Oak Ridge National Laboratory

Edwards Air Force Base

Massachusetts Institute of Technology

Ludwig-Maximilians-Universität München

University of Alabama

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Formamidinium Nitroformate: An Insensitive RDX Alternative

Journal of the American Chemical Society (2018)

Amanda F. Baxter Igor Martin Karl O. Christe Ralf Haiges

Five nitroformate (trinitromethanide) salts featuring nitrogen-containing cations were prepared. The salts were characterized by multinuclear NMR, IR, and Raman spectroscopy, single-crystal X-ray analysis, differential thermal analysis, and friction and impact sensitivity testing. These experimental data are supplemented with thermochemical calculations using the Gaussian-4 composite method, and the performance of these energetic materials was calculated based on the Chapman-Jouguet thermodynamic detonation theory. Out of the five compounds studied by us, the formamidinium salt, [CH(NH2)2]+[C(NO2)3]-, is most interesting. Its performance matches that of RDX (research department explosive, cyclotrimethylenetrinitramine), while it is much less sensitive to impact and friction and, therefore, might be an excellent, less sensitive replacement for RDX.

Formamidinium

Energetic material

10.1021/jacs.8b10200

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Citations (53)

Fluoro‐nitrogen Cations

Angewandte Chemie International Edition (2021)

Ashwani Vij William W. Wilson Ralf Haiges Kyle C. Edwards David A. Dixon

The crystal structures of [NH3 F]+ [CF3 SO3 ]- , [NH2 F2 ]+ [SbF6 ]- , and [N2 F3 ]+ [Sb3 F16 ]- have been determined, representing the first structural characterizations of these simple fluoro-nitrogen cations. The influences of the hybridization of the central nitrogen atom and of the number of fluorine substituents on the N-F bond lengths are evaluated for the series N2 F+ , N2 F3+ , NF2 O+ , NH3 F+ , NH2 F2+ , and NF4+ . It is shown that the N-F bond length decreases from 1.40 Å to 1.26 Å with increasing fluorine substitution and increasing s-character of the nitrogen atom, and that unusual N-F bond lengths reported in the previous literature are caused by disorder problems.

Nitrogen atom

Fluorine

Crystal (programming language)

10.1002/anie.202116565

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CCDC 1919868: Experimental Crystal Structure Determination

The Cambridge Structural Database (2019)

Kavita Belligund Thomas Mathew Jonathan R. Hunt Archith Nirmalchandar Ralf Haiges

10.5517/ccdc.csd.cc22fs7k

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CCDC 1855716: Experimental Crystal Structure Determination

The Cambridge Structural Database (2018)

Thomas Saal Karl O. Christe Ralf Haiges

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/ccdc.csd.cc2090t5

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CCDC 1891653: Experimental Crystal Structure Determination

The Cambridge Structural Database (2019)

Thomas Saal Piyush Deokar Karl O. Christe Ralf Haiges

10.5517/ccdc.csd.cc21hf22

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Front Cover: α‐Fluoroalcohols: Synthesis and Characterization of Perfluorinated Methanol, Ethanol and n‐Propanol, and their Oxonium Salts (Chem. Eur. J. 63/2018)

Chemistry - A European Journal (2018)

Amanda F. Baxter Jonas Schaab Joachim Hegge Thomas Saal Monica Vasiliu

Perfluoroalcohols: Although thermally unstable, these alcohols can be readily accessed through equilibria of the corresponding acyl fluorides with HF in anhydrous HF solution. These equilibria can be shifted to the side of the alcohols by trapping them as oxonium salts, ethers or alkoxides, thus making these reactions synthetically useful. More information can be found in the Communication by K. O. Christe et al. on page 16742. Perfluoroalcohols: Although thermally unstable, these alcohols can be readily accessed through equilibria of the corresponding acyl fluorides with HF in anhydrous HF solution. These equilibria can be shifted to the side of the alcohols by trapping them as oxonium salts, ethers or alkoxides, thus making these reactions synthetically useful. More information can be found in the Communication by K. O. Christe et al. on page 16742.

Oxonium ion

Anhydrous

Front cover

Tetramethylammonium

10.1002/chem.201804866

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ChemInform Abstract: The First Molybdenum(VI) and Tungsten(VI) Oxoazides MO₂(N₃)₂, MO₂(N₃)₂·2CH₃CN, (bipy)MO₂(N₃)₂, and [MO₂(N₃)₄]^2‐ (M: Mo, W).

ChemInform (2015)

Ralf Haiges Juri Skotnitzki Zongtang Fang David A. Dixon Karl O. Christe

Abstract The title compounds are prepared via fluoride‐azide exchange (caution: polyazides are very shock‐sensitive and can explode violently!) and characterized by vibrational spectroscopy, impact, friction, and thermal sensitivity data.

10.1002/chin.201542019

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Amine‐Free Reversible Hydrogen Storage in Formate Salts Catalyzed by Ruthenium Pincer Complex without pH Control or Solvent Change

ChemSusChem (2015)

Jotheeswari Kothandaraman Miklós Czaun Alain Goeppert Ralf Haiges John‐Paul Jones

Abstract Due to the intermittent nature of most renewable energy sources, such as solar and wind, energy storage is increasingly required. Since electricity is difficult to store, hydrogen obtained by electrochemical water splitting has been proposed as an energy carrier. However, the handling and transportation of hydrogen in large quantities is in itself a challenge. We therefore present here a method for hydrogen storage based on a CO 2 (HCO 3 − )/H 2 and formate equilibrium. This amine‐free and efficient reversible system (>90 % yield in both directions) is catalyzed by well‐defined and commercially available Ru pincer complexes. The formate dehydrogenation was triggered by simple pressure swing without requiring external pH control or the change of either the solvent or the catalyst. Up to six hydrogenation–dehydrogenation cycles were performed and the catalyst performance remained steady with high selectivity (CO free H 2 /CO 2 mixture was produced).

10.1002/cssc.201403458

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Citations (124)

Symmetric pyrrolic squaraines and their application to organic photovoltaics

Journal of Photochemistry and Photobiology A Chemistry (2019)

Piyumie Wickramsinghe Piyush Deokar Peter I. Djurovich Ralf Haiges Mark E. Thompson

Photocurrent

Open-circuit voltage

Quantum Efficiency

10.1016/j.jphotochem.2019.01.017

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Citations (10)

Influence of Intermolecular Hydrogen Bonding Interactions on the Electrocatalytic Reduction of CO₂ to CO by 6,6′‐Amine Substituted Rhenium Bipyridine Complexes

ChemElectroChem (2021)

Ashley N. Hellman Ralf Haiges Smaranda C. Marinescu

Abstract The introduction of biologically inspired motifs into electrocatalysts is an attractive strategy for efficiently transforming harmful fossil fuel combustion products such as carbon dioxide into useful chemical fuels. Herein, we present a series of Re(bpy)(CO) 3 Cl electrocatalysts with pendant primary, secondary, and tertiary amines with the aim of determining the effect of available pendant protons on the reduction of CO 2 to CO. Cyclic voltammetry studies indicate that the availability of pendant protons leads to intermolecular hydrogen bonding interactions, altering the electrochemical behavior of the complexes. Further, controlled potential electrolysis studies show a clear trend in the catalytic activity of these complexes based on the availability of pendant protons. For the NMe 2 ‐substituted complex with no pendant protons, the Faradaic efficiency (FE) remains quite stable with changing potential (41–65 % FE CO ), but for the NH 2 ‐substituted complex with maximum available pendant protons, the FE CO increases with more negative potentials, peaking at 83 % FE CO . Together with the formation of H 2 by the NH 2 ‐substituted Re(bpy)(CO) 3 Cl complex, this suggests a change in electrocatalytic behavior due to the intermolecular hydrogen bonding interactions that occur with additional pendant protons.

Bulk electrolysis

Bipyridine

10.1002/celc.202100306

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Citations (10)