| Polyazide Chemistry. Preparation and Characterization of the First Binary Group 6 Azides, Mo(N3)6, W(N3)6, Mo(N3)7- and W(N3)7- and the NW(N3)4- and NMo(N3)4- Ions |
NOV 2004 |
6 pages |
| Authors:
Ralf Haiges; Jerry A. Boatz; Robert Bau; Stefan Schneider; Thorsten Schroer; Muhammed Yousufuddin; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
 | Whereas numerous binary transition-metal azido complexes have been reported,1 no binary Group 6 azides are known. Only a limited number of partially azide-substituted molybdenum and tungsten compounds have been reported. Furthermore, no heptaazido compounds have been described. Herein, we report the synthesis and characterization of the first binary Group 6 azides, Mo(N3)6, W(N3)6, Mo(N3)7-, and W(N3)7-. The last two ions represent the first examples of heptaazides. We also report the ... |
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| History of the AFRL/USC DARPA Program on Polynitrogen Chemistry. Volume 2 |
OCT 2004 |
143 pages |
| Authors:
Karl O. Christe; Ashwani Vij; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| In the course of the High Energy Density Matter (HEDM) Program, which was initiated in 1986 by the Air Force, the potential of polynitrogen compounds for HEDM was recognized by numerous theoretical studies. However, no systematic efforts were undertaken to synthesize any of the potential candidates predicted by the theoreticians. This changed in 1998, when Dr. Oestmark from the Swedish Defense Research Agency proposed to DARPA an experimental study to ... |
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| Polyazide Chemistry Preparation and Characterization of As(N3)5, Sb(N3)5 and P(C6H5)4Sb(N3)6 |
SEP 2004 |
19 pages |
| Authors:
Ralf Haiges; Jerry A. Boatz; Ashwani Vij; Vandana Vij; Michael Gerken; Stefan Schneider; Thorsten Schroer; Muhammed Yousufuddin; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The binary arsenic- and antimony azide species AS(N3)3, As(N3)4+, As(N3)4-, As(N3)6-, Sb(N3)3, Sb(N3)4+, Sb(N3)4- and Sb(N3)6- have previously been reported, and the crystal structures of As(N3)3, Sb(N3)3 and As(N3)6- were determined. In addition, the Lewis based stabilized species M(N3)5-LB (M=As,Sb; LB=pyridine, quinoline NH3, N2H4, NH2CN) were published. However, previous attempts to obtain the neat pentaazides of arsenic and antimony were not successful. Even at low temperatures, attempted syntheses resulted in ... |
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| Volume 1: The Solid-Gas Singlet Delta Oxygen Generator |
AUG 2004 |
49 pages |
| Authors:
Angelo J. Alfano; Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| The recently completed research program at the Air Force Research Laboratory, Edwards AFB Site, had as its goals for the component dealing with solid-gas generation of singlet delta oxygen: a) construction of a Raman diagnostic system for the simultaneous measurement of excited and ground state oxygen in gas-solid reactions between solid peroxides and hydrogen halides or chlorine gas, b) exploration of alternate singlet delta oxygen sources, and c) technical chemistry ... |
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| Improved Synthesis and Reaction Chemistry of FN3 |
07 JUN 2004 |
25 pages |
| Authors:
William W. Wilson; Karl O. Christe; Aswward Vij; Ralf Haiges; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| FN3 was first prepared by J. F. Haller at Cornell University in 1942. Very little work was done with FN3 because of its extreme shock sensitivity and thermal instability. Characterized by D. J. Benard in 1986 and by H. Willner in 1987 on very small scale. Yields were low, and purification and handling presented major problems. Development of a safe high yield process for pure FN3 was mandatory for studying ... |
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| The NH3Cl+ Cation |
21 MAY 2004 |
20 pages |
| Authors:
Stefan Schneider; Ralf Haiges; Thorsten Schroer; Jerry Boatz; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| Whereas at least seven simple inorganic cations, NH3F+,1,2 NH2F2+,3 NF4+,4 N2F+,5 N2F3+,6 ONF2+,7 and N3NOF+,8 which contain N-F bonds, have been prepared and well characterized, the existence of corresponding N-Cl containing cations is not well established. Thus, only two N-Cl containing cations, NCl4+9 and ONCl2+,10,11 have been reported, however, our repeated attempts to duplicate their syntheses were unsuccessful, and the crystal structure, published for ONCl2+SbCl6-,10 has been challenged on theoretical ... |
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| Polynitrogen Chemistry: Recent Development in Pentazole and Polyazide Chemistry |
24 MAR 2004 |
18 pages |
| Authors:
Ashwani Vij; Vandan Vij; R. Haiges; Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| Partial contents: Polynitrogen Chemistry: Recent Development in Pentazole and Polyazide Chemistry, Why Polynitrogen Compounds?, Geometry of the N5+ cation , (In) Compatabillty of N5+, New Polynitrogen Anions as Counterparts for N5+, Synthetic Challenge How do we make These New Anions??, Formation and Stabillty of Sllyl Diazonium Salts, Synthesis of Aryldiazonium Salts, Pentazole Formation.. Not a Trivial Chore!!!, Identification of Arylpentazoles, Cleavage of the Aryl-Pentazole Bond with Retention of the Pentazole ... |
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| High Energy Density Materials |
23 MAR 2004 |
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| Authors:
Ralf Haiges; Stefan Schneider; Thorsten Schroer; Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INCHUNTSVILLE AL
|
 | During the past two decades, polynitrogen compounds have received increasing attention as promising candidates for High Energy Density Materials (HEDM).1-17 While most of the efforts were devoted to theoretical studies, the long-known existence of the stable azide anion (N3-)18 and the recent syntheses of stable salts of the pentanitrogen cation (N5+)1-3 have demonstrated the feasibility of experimentally pursuing such materials. The only known direct method for preparing N5+ compounds is ... |
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| Preparation and Characterization of the First Binary Titanium Azides, Ti(N3)4, P(C6H5)4Ti(N3)5 and P(C6H5)42Ti(N3)6 and on Linear Ti-N-NN Coordination |
12 MAR 2004 |
21 pages |
| Authors:
Karl O. Christe; Ralf Haiges; Stefan Schneider; Thorsten Schroer; Jerry A. Boatz; ENGINEERING RESEARCH AND CONSULTING INCHUNTSVILLE AL
|
| Where as numerous partially azide-substituted titanium compounds had previously been reported, 1-7 no binary titanium azides were known. In a recent theoretical study the group 4 metal tetrazides M(N3)4 (M = Ti, Zr, Hf, Th) were predicted 8 to be vibrationally stable exhibiting tetrahedral structures with unique linear M-N-NN bond angles (see Figure 1). All previously characterized covalent binary azide species possess bent M-N-NN angles. In this paper we wish ... |
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| Polynitrogen Chemistry |
23 SEP 2003 |
31 pages |
| Authors:
Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| The novel Ns +HF2 salt was prepared and serves as a useful reagent for the preparation of other N5 + salts. The reactions of NF4+ and N2F3+ with HN3 were studied. WHile NF4+ acted only as a fluorinating agent, one F of N2F3 + was replaced by an azido group, but the substitution product was unstable and underwent rapid decomposition. The decomposition of complex fluoro salts of N2 + was ... |
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| Quantitative Measure for the Nakedness of Fluoride Ion Sources |
23 APR 2003 |
22 pages |
| Authors:
Karl O. Christe; B. Jenkins; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| A quantitative measure for the donor strength or "nakedness" of fluoride ion donors is presented. It is based on the free energy change associated with the transfer of a fluoride ion from the donor to a given acceptor molecule. Born-Haber cycle calculations were used to calculate both the free energy and enthalpy change for this process. |
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| Polynitrogen Chemistry. Preparation and Characterization of (N5)2SnF6, N5SnF5, and N5B(CF3)4 |
21 MAR 2003 |
22 pages |
| Authors:
William W. Wilson; Ashwani Vij; Vandana Vij; Eduard Bernhardt; Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| The successful synthesis of the 2:1 salt (N5+)2SnF6(2-) demonstrates that compounds with touching polynitrogen cations can be prepared, and that the synthesis of an ionic, all nitrogen compound is in principal possible. This paper also shows that N5+ salts, other than N5SbF6 and N5AsF6, can be prepared by metathetical reactions. This method was applied to the syntheses of N5B(CF3) 4, N5+SnF(5), and (N5(+))2SnF6(2-). |
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| Synthesis and Characterization of the trans-IO2F5(2-) Dianion |
11 FEB 2003 |
|
| Authors:
Jerry A. Boatz; William J. Casteel Jr.; Karl O. Christe; David A. Dixon; Michel Gerken; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| The combination of CH3CN solutions of N(CH3)4F and a mixture of cis- and trans-N(CH3)4IO2F4 produces the novel trans-IO2F5(2-) anion. Under the given conditions, only the trans-IO2F4(-) anion acts as a fluoride ion acceptor, thus allowing the separation of isomerically pure, soluble cis-IO2F4(-) from insoluble trans-IO2F5(2-). |
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| Enthalpies of Formation of Gas Phase N3, N3(-), N3(+), and N5(-) from Ab Initio Molecular Orbital Theory, Stability( Predictions for N5(+) N3(-) and N5(+) N5(-), and Experimental Evidence for the Instability of N5(+) N3(-) |
2003 |
36 pages |
| Authors:
David A. Dixon; Davied Feller; Karl O. Christe; William W. Wilson; Ashwani Vij; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3(-), N5(+), and N5(-) from total atomization energies. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, permit for the first time reliable stability predictions for the hypothetical N5(+) N3(-) and N5(+)N5(-) salts. Contrary to ... |
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| Tritylsulfinylamine: A New Member in the Family of Sulfinylamines |
25 SEP 2002 |
23 pages |
| Authors:
Karl O. Christe; Michael Gerken; Ralf Haiges; Stefan Schneider; Thorsten Schroer; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CHEMISTRY
|
| Triphenylmethyl N-sulfinylamine (trityl-NSO) was prepared from the reaction of trityl amine and SOCl2. Trityl-NSO was characterized by 1H, 13C, and 14N NMR spectroscopy in CH2C12 solution and by Raman and infrared spectroscopy in the solid state. Crystals of trityl NSO were grown from n-heptane and characterized by single crystal X-ray diffraction (P1-bar, alpha = 8.9642(9) A, b = 9.2135(9) A, c = 11.0645(11) A, alpha = 93.578(2)0, Beta = 101.098(2)0, ... |
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| Synthesis and Structural Characterization of Nitrogen Containing High Energy Density Materials |
18 JUN 2002 |
3 pages |
| Authors:
Karl O. Christe; Ashwani Vij; Vandana Vij; William W. Wilson; Fook S. Tham; ENGINEERING RESEARCH AND CONSULTING INCEDWARDS AFB CA
|
| In this paper we report the crystal structures of the novel N5+ cation in N5+Sb2F11-, which is the first stable polynitrogen species to be discovered in a century since the discovery of the azide ion. |
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| Studies on the Generation of the Pentazole Anion and Singlet-Delta Molecular Oxygen |
09 MAY 2002 |
3 pages |
| Authors:
Karl O. Christe; William W. Wilson; Ashwani Vij; Vandana Vij; Angelo Alfano; ENGINEERING RESEARCH AND CONSULTING INCEDWARDS AFB CA
|
| Under combined DARPA, AFOSR and NSF sponsorship, we have discovered, in 1999, the novel polynitrogen cation, N5+. |
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| New Polynitrogen Molecules -- Energetic Air as a Next-Generation Propellant? |
29 APR 2002 |
|
| Authors:
Karl O. Christe; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The identification, development, and formulation of new energetic materials for advanced rocket propulsion applications is an area of long- standing interest to the Air Force. The performance limits of currently used propellants have been reached, so new energetic compounds are required to significantly improve the ability of the warfighter to access and control space. Polynitrogen species such as the recently discovered N5+ cation are of interest as potential energetic ingredients ... |
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| Triphenylmethyldifluoramine: A Stable Reagent for the Synthesis of gem- Bis(difluoramines) |
29 APR 2002 |
|
| Authors:
G. K. Prakash; Markus Etzkorn; George A. Olah; Karl O. Christe; Stefan Schneider; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST
|
| The conversion of ketones into geminal bis(difluoramines) can be achieved under mild two phase reaction conditions by employing triphenylmethyldifluoramine as an in situ source of difluoramine. |
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| Experimental Detection of the Pentazole Anion, N5(-) |
01 APR 2002 |
13 pages |
| Authors:
Ashwani Vij; James G. Pavlovich; William W. Wilson; Karl O. Christe; CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
|
| The pentazole anion has been generated from para- hydroxyphenylpentazole and identified by electrospray ionization mass spectrometry. Whereas at low collision voltages the para-phenoxypentazole anion undergoes stepwise N2 elimination generating the corresponding azide and nitrene, at high collision voltages the N5(-) anion is formed. Fragmentation of the pentazole anion produces the N3(-) anion as the principal negative ion. These experiments provide the first experimental proof for the existence of the pentazole ... |
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| Synthesis and Characterization of the SO2N3(-), (SO2)2N3(-), and SO3N3(- ) Anions |
06 MAR 2002 |
51 pages |
| Authors:
Karl O. Christe; Jerry A. Boatz; Michael Gerken; Ralf Haiges; Stefan Schneider; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| SO2 solutions of azide anions are bright yellow and their Raman spectra indicate the presence of covalently bound azide. Removal of the solvent at -64 deg C from CsN3 or N(CH3)4N3 solutions produces yellow (SO2)2N3(-) salts. Above -64 deg C, these salts lose one mole of SO2, resulting in white SO2N3 salts that are marginally stable at room temperature and thermally decompose to the corresponding azides and SO2. |
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| Singlet Delta Oxygen Production from a Gas-Solid Reaction |
14 FEB 2002 |
14 pages |
| Authors:
Angelo J. Alfano; Karl O. Christe; ENGINEERING RESEARCH AND CONSULTING INCEDWARDS AFB CA
|
| Spontaneous reactions between solid alkali metal or alkaline earth peroxides and hydrogen (deuterium) halide gases demonstrate the efficient production of singlet delta oxygen in a non-liquid medium. These reactions occur under ambient conditions without the need for any external energy source. The production of singlet delta oxygen was verified by direct emission spectroscopy at 1.27 microns with a calibrated optical multi-channel analyzer. These reactions overcome the severe quenching problems encountered ... |
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| Improved Synthesis of CsN3 |
17 DEC 2001 |
7 pages |
| Authors:
Michael Gerken; Stefan Schneider; Thorsten Schroer; Karl O. Christe; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST
|
| Cesium azide can conveniently be prepared from anhydrous CsF and (CH3)3SiN3 in SO2 solvent in high purity and yield. In this reaction, the initially generated SO2F(-) anion is converted in SO2 solvent to solvated azide, (SO2)(sub n)N3(-), which is labile and releases S02 under dynamic vacuum yielding pure CsN3. |
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| A New Synthesis of Anhydrous Cesium Salts |
OCT 2001 |
9 pages |
| Authors:
Ralf Haiges; Karl O. Christe; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST
|
| Contrary to ammonium salts many cesium salts are extremely hygroscopic. Consequently, anhydrous ammonium salts are readily available in anhydrous form by neutralizing the corresponding acids with ammonia, but their conversion to anhydrous cesium salts is difficult. |
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| Polynitrogen Chemistry and the Pursuit of New High Energy Density Materials |
13 APR 2001 |
3 pages |
| Authors:
Karl O. Christe; William W. Wilson; Ashwani Vij; Vandana Vij; Jeffrey A. Sheehy; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| The goal of this AFOSR program is the synthesis of novel polynitrogen-derived HEDM compounds, exploiting the synergism between theory and synthesis. Under combined DARPA, AFOSR and NSF sponsorship, we have discovered in 1999 the novel polynitrogen compound, N5(+)AsF6(-). The N5(+) cation is only the third known, homoleptic polynitrogen species that can be prepared and isolated in bulk, the other two being N2 and the azide anion. N5(+)AsF6(-) was found to ... |
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| Synthesis and Characterization of the First Examples of Perfluoroalkyl Substituted Trialkyl-Oxonium Salts, (CH3)2OCF3(+)Sb2F11(-) and (CH3)2OCF(CF3) 2(+) Sb2F11(-) |
16 MAR 2001 |
22 pages |
| Authors:
Joachim Hegge; Berthoid Hoge; Jeffrey A. Sheehy; Karl O. Christe; Rolf Minkwitz; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST
|
| In the superacidic HF/SbF5 system, methyl-trifluoromethylether forms at -78 deg C the new tertiary oxonium salt, (CH3)2OCF3(+)Sb2F11(-), that was characterized by Raman and multinuclear NMR spectroscopy and its crystal structure. The same oxonium salt was also obtained by methylation of CH3OCF3 with CH3F and SbF5 in HF solution at -30 to -10 deg C. Replacement of one methyl group in the trimethyloxonium cation by the bulkier and more electronegative trifluoromethyl ... |
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| Polynitrogen Chemistry, Synthesis, Characterization, and Crystal Structure of Surprisingly Stable Fluoroantimonate Salts of N5(+) |
01 MAR 2001 |
48 pages |
| Authors:
Ashwani Vij; William W. Wilson; Vandana Vij; Fook S. Tham; Karl O. Christe; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST
|
| The new N5(+) salt, N5(+)SbF6(-), was prepared from N2F(+)SbF6(-) and HN3 in anhydrous HF solution. The white solid is surprisingly stable, decomposing only at 70 deg C, and is relatively insensitive to impact. Its vibrational spectrum exhibits all nine fundamentals with frequencies that are in excellent agreement with the theoretical calculations for a five-atomic V-shaped ion of C2v symmetry. The N5(+)Sb2F11(-) salt was also prepared and its crystal structure was ... |
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| A Renaissance in Noble-Gas Chemistry |
12 FEB 2001 |
12 pages |
| Authors:
Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| In spite of the predictions of stable noble-gas compounds since at least 1902, unsuccessful attempts at their synthesis gave rise to the widely held opinion that noble-gases are not only noble but also inert . Thus, dogma- like statements to this effect could be found in practically every chemistry textbook and discouraged or a long time, experimentalists to work in this area. It was not until 1962 that this dogma ... |
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| In Pursuit of the PO2+ Cation. The Reaction of KPO2F2 and SbF5 Leads to an Eight-Membered, Antimony-Oxygen-Phosphorus-Bridged Ring |
08 DEC 2000 |
29 pages |
| Authors:
Stefan Schneider; Ashwani Vij; Jeffrey A. Sheehy; Thorsten Schroer; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The reaction of KPO2F2 with the strong Lewis acid SbF3 was studied as a potential pathway to the unknown PO2(+) cation. The resulting product has the desired PO2SbF6 composition but consists of an eight-membered, oxygen-bridged ring that was characterized by vibrational and NMR spectroscopy, ab initio methods, and a single crystal x-ray diffraction study. The formation of the oxygen-bridged ring and its mechanism are discussed. |
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| Crystal Structure of CIF4+SbF6-, Normal Coordinate Analyses of CIF4+ BrF4+, IF4+, SF4, SeF4, and TeF4, and Simple Method for Calculating the Effects of Fluorine Bridging on the Structure and Vibrational Spectra of Ions in a Strongly Interacting Ionic Soli |
12 OCT 2000 |
53 pages |
| Authors:
Karl O. Christe; Xiongzhi Zhang; Jeffrey A. Sheehy; Robert Bau; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The crystal structure of the 1:1 adduct ClF5-SbF5 was determined and contains discrete ClF4(+) and SbF6(-) ions. The ClF4(+) cation has a pseudo- trigonal bipyramidal structure with two longer and more ionic axial bonds and two shorter and more covalent equatorial bonds. The third equatorial position is occupied by a sterically active free valence electron pair of chlorine. The coordination about the chlorine atom is completed by two longer fluorine ... |
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| Novel Synthesis of CIF6+ and BrF6+ |
04 OCT 2000 |
27 pages |
| Authors:
Thorsten Schroer; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| For a compound in a given oxidation state, its oxidizing strength increases from its anion to the neutral parent molecule to its cation. Similarly, an anion is more easily oxidized than its neutral parent molecule, which in turn is more easily oxidized than its cation. This concept was systematically exploited in our search for new superoxidizers. Transition metal fluoride anions were prepared in their highest known oxidation states by high ... |
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| Theory and Synthesis of New High Energy Density Materials |
03 OCT 2000 |
5 pages |
| Authors:
Karl O. Christe; William W. Wilson; Ashwani Vij; Jeffrey A. Sheehy; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The aim of this AFOSR program is the synthesis of novel HEDM compounds, exploiting the synergism between theory and synthesis. Theoretical calculations are routinely used to guide the synthesis efforts and to facilitate the identification and characterization of the products. |
|
| Chemistry of N-F Containing HEDM Materials and on Lewis Acidity of LiF |
03 OCT 2000 |
4 pages |
| Authors:
Vandana Vij; Ashwani Vij; William W. Wilson; Karl O. Christe; Jeffery A. Sheehy; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The recent isolation of the N5+ cation is one of the most amazing discoveries of modern chemistry. This statement is justified by the fact that this is the first all nitrogen homoleptic species to be isolated in more than a century, and only the third known species of this kind besides atmospheric nitrogen (N2) and the azide ion (N3(-)). The N5(+)AsF6(-) salt is only marginally stable at room temperature. In ... |
|
| Method for Solving Some Disordered Crystal Structures and its Application to the Structures of NF2O+ and SO2F- |
SEP 2000 |
3 pages |
| Authors:
Karl O. Christe; Ashwani Vij; Rudiger Mews; Xiongzhi Zhang; Jerry Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| Oxygen and fluorine ligands are similar in size and frequently exhibit positional disorder in the crystal structures of oxofluorides, resulting in a partial or complete averaging of the observed bond lengths and angles. The failure to recognize the presence of disorder has resulted in the publication of numerous incorrect structures, while the recognition of disorder problems has generally prompted researchers to abandon these data sets. In this paper, a method ... |
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| Recent Progress in Nitrogen Fluoride Chemistry |
SEP 2000 |
3 pages |
| Authors:
Vandana Vij; Ashwani Vij; William W. Wilson; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| For the preparation of N5+ salts on a larger scale, it was necessary to prepare the corresponding precursors in an efficient manner and in large quantities. In this paper, process improvements in this direction are described. Furthermore, the catalytic conversion of trans-N2F2 to its cis-isomer is discussed. Also discovered during the isomerization studies was a novel synthetic route to NF4+ salts at relatively low temperature and pressure. A structural analysis ... |
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| The Structure of the SO2F Anion, A Problem Case |
19 JUN 2000 |
39 pages |
| Authors:
Paul G. Watson; Tobias Borrmann; Ashwani Vij; Jerry A. Boatz; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| Recently, room-temperature crystal structures of SO2F(-) in its K(+) and Rb(+) salts were published in Z. Among. Allg. Chem. 1999, 625, 385 and claimed to represent the first reliable geometries for SO2F(-). However, their almost identical 5-O and S-F bond lengths and O-S-O and O-S-F bond angles are in sharp contrast to the results from theoretical calculations. To clarify this discrepancy, the new (CH3)2N3SO(+) and the known N(CM3)4(+), (CH3)2N3S(+) and ... |
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| The Tetrafluorohalogen Cations CIF4+, BrF4+, and IF4+ and Their Isoelectronic Counterparts SF4, SeF4, and TeF4 |
08 FEB 2000 |
3 pages |
| Authors:
Karl O. Christe; Xiongzhi Zhang; Jeffrey A. Sheehy; Robert Bau; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The crystal structure of the 1:1 adduct, ClF5SbF5, was determined and shown to contain discrete ClF4+ and SbF6- ions. |
|
| Relative Abilities of Fluorine and Chlorine to Stabilize Carbenium Ions. Crystal Structures of Two Fluoro-Substituted Carbocations and of As2F11 |
01 NOV 1999 |
47 pages |
| Authors:
Karl O. Christe; Xiongzhi Zhang; Robert Bau; Joachim Hegge; George A. Olah; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The first crystal structures of fluoro-substituted carbocations without heteroatom stabilization and of the As2F11(-) anion are reported. The experimental geometries of the carbenium ions in (CH3)2CF(+)asF6(-), (M-CF3C6H4) (C6H5)CF(+)asF6(-) and (M-CF3C6H4)(C6H5)CF(+)as2F11(-) and their comparison with that of the (0-ClC6H4)(C6H5)CCl(+) cation show that, in accord with previous theoretical calculations, chlorine stabilizes carbenium ions more efficiently than fluorine. The apparent discrepancy between these findings and a previously reached conclusion, based on an analysis ... |
|
| On a Quantitative Scale for Lewis Acidity and Recent Progress in Polynitrogen Chemistry |
27 MAY 1999 |
9 pages |
| Authors:
Karl O. Christe; David A. Dixon; Douglas McLemore; William W. Wilson; Jeffrey A. Sheehy; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| A quantitative scale for Lewis acidities based on fluoride ion affinities is discussed. It uses pH values which represent the fluoride ion affinities in kcal/mol divided by 10. These values were obtained for 106 Lewis acids in a self-consistent manner using ab initio calculations at the MP2/PDZ level of theory. In the area of polynitrogen chemistry, the synthesis and characterization of the novel N5+ cation from N2F(+) and HN3 is ... |
|
| Synthesis of Catenated Polynitrogen Compounds |
27 MAY 1999 |
32 pages |
| Authors:
Karl O. Christe; William W. Wilson; Jerry A. Boatz; Jeffrey A. Sheehy; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| Presentation includes overview of synthesis of novel compounds consisting of highly endothermic polynitrogen allotropes; use techniques developed in synthesis of other energetic materials to pursue catenated rather than polycyclic polynitrogen compounds; use theory and calculations to guide synthesis efforts; and potential payoffs. |
|
| High Energy Density Materials: Synthesis and Characterization of the Pentanitrogen (1+) Cation, N5+, A Novel Homoleptic Polynitrogen Ion |
12 MAY 1999 |
24 pages |
| Authors:
Karl O. Christe; William W. Wilson; Jeffrey A. Sheehy; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Polynitrogen compounds are of significant interest as high energy density materials (HEDM) for propulsion or explosive applications. In spite of numerous theoretical studies predicting that certain all-nitrogen compounds might be stable, however, only a few unsuccessful experimental studies aimed at their actual synthesis have been undertaken. |
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| Crystal Structure of Hexamethylguanidinium Hexafluorosilicate Hexahydrate |
05 MAR 1999 |
20 pages |
| Authors:
Xiongzhi Zhang; Robert Bau; Jeffrey A. Sheehy; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Single crystals of the hexamethylguanidinium hexafluorosilicate hexahydrate salt, C(NMe2)32(+)SiF6(2-)(dot) 6H2O, were isolated when a product, obtained by water removal from aqueous C(NMe2)3F in a glass vessel, was recrystallized from CH3OH. The crystal structure of this salt was determined, and the structure of the free hexamethylguanidinium cation was calculated, showing that the propeller-shaped structure of the hexamethylguanidinium cation is not caused by solid state effects but is the true minimum energy ... |
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| Experimental and Theoretical Characterization of the Oxygen-Coordinated Donor-Adducts of COCl2, COClF and COF2 with AsF5 and SbF5 |
04 MAR 1999 |
24 pages |
| Authors:
Berthold Hoge; Jerry A. Boatz; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
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| When reacted with an excess of the corresponding carbonyl halides, AsF5 and SbF5 from the following 1:1 adducts: COCl2*AsF5, COCl2*SbF5, COCIF*AsF5, COClF*SbF5, COF2*AsF5 and COF2*SbF5. All adducts are unstable at ambient temperature, and their dissociation enthalpies were determined from the dissociation pressure curves. Vibrational and multinuclear NMR spectra and theoretical calculations show that all compounds are oxygen-coordinated donor- acceptor adducts, and that the strengths of the oxygen-bridges increase from COF2 ... |
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| A Quantitative Scale for the Strength of Lewis Acids and On the Reaction of H2F+ With HN3 and the Synthesis and Characterization of N5+AsF6- |
10 FEB 1999 |
28 pages |
| Authors:
Karl O. Christe; David A. Dixon; Douglas McLemore; William W. Wilson; Jeffrey A. Sheehy; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Presentation of a quantitative scale for the strength of Lewis acids and the reaction of N2F+ with HN3 and the synthesis and characterization of N5+AsF6-. |
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| Hepta-Coordination. Synthesis and Characterization of the IOF52- Dianion, an XOF5E Compound |
06 JAN 1999 |
16 pages |
| Authors:
Karl O. Christe; William W. Wilson; David A. Dixon; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The new IOF5(sup 2-) dianion was prepared in the form of its cesium salt by heating stoichiometric amounts of CsF, I2O5 and IF5 to 162 deg C for 14 days. The white stable solid was characterized by vibrational spectroscopy. A normal coordinate analysis was carried out with the help of ab initio calculations at the HF/ECP/DZP level of theory and resulted in an excellent agreement between observed and calculated frequencies. ... |
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| Theory and Synthesis of New High Energy Density Materials |
30 APR 1998 |
19 pages |
| Authors:
Karl O. Christe; William W. Wilson; Greg W. Drake; Jeff A. Sheehy; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Efforts are described to combine the NF4+ cation with highly energetic anions, such as NO(2), NO(3), and N(NO2)2. In the case of NO(3), the NO(3) anion was fluorinated already at very low temperatures by NF(4) to give fluorine nitrate in high yield. In the case of NO(2), the reaction with NF(4) yielded an unknown unstable decomposition product in low yield, but the reaction was very difficult to control and consistently ... |
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| The New Bicyclic Nitrogen Tetroxide Cation, NO4(+) Has a Low Decomposition Energy |
17 MAR 1998 |
9 pages |
| Authors:
Anatoli A. Korkin; Rodney J. Bartlett; Marcel Nooijen; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Nitrogen oxide cations, such as NO2(+) and NO(+), are strong oxidizers and useful components for ionic High Energy Density Materials (HEDM) 1. Their energy content and oxidizing power increase with increasing oxidation state of the nitrogen atom and the number of oxygen ligands. In our search for related, halogen-free, highly energetic cations we have became interested in the bicyclic NO4(+)(I). |
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| Pentagonal Planar AX5 Species: Synthesis and Characterization of the Iodine (III) Pentafluoride Dianion, IF5 |
13 JAN 1998 |
26 pages |
| Authors:
Karl O. Christe; William W. Wilson; Greg W. Drake; David A. Dixon; Jerry A. Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| The new IF5(2-) dianion, which is5 species, was prepared as its N(CH3)4(+) salt from N(CH3)4IF4 and N(CH3)4F in CH3CN solution. Its structure was established by infrared and Raman spectroscopy, ab initio calculations and a comparison to isoelectronic XeF5(-). Furthermore, vibrational spectroscopy and x-ray powder diffraction data show that the previously reported composition 'Cs3IF6', is actually a mixture of Cs2IF5 and CsF. Ab initio calculations also show that the most probable ... |
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| Crystal Structure of Hexamethylguanidinium Hexafluorosilicate Hexahydrate |
1998 |
18 pages |
| Authors:
Xiongzhi Zhang; Robert Bau; Jeffrey A. Sheehy; Karl O. Christe; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Single crystals of the hexamethylguanidinium hexafluorosilicate hexahydrate salt, C(NMe2)32(+)SiF6(2-)(dot) 6H2O, were isolated when a product, obtained by water removal from aqueous C(NMe2)3F in a glass vessel, was recrystallized from CH3OH. The crystal structure of this salt was determined, and the structure of the free hexamethylguanidinium cation was calculated, showing that the propeller-shaped structure of the hexamethylguanidinium cation is not caused by solid state effects but is the true minimum energy ... |
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| Novel Fluorine Oxidizers |
FEB 94 |
48 pages |
| Authors:
Karl O. Christe; William W. Wilson; ROCKWELL INTERNATIONAL CANOGA PARK CA ROCKETDYNE DIV
|
| This reports the results of a three-year program in novel energetic materials. The majority of the results was summarized in 30 manuscripts which are in various stages of publication. Major achievements include the synthesis of the ClF6(-) anion, the combination of the N(CH3)4(+) cation with powerful halogen fluorine anion oxidizers, the synthesis of truly anhydrous N(CH3)4F which generated a worldwide renaissance in high coordination number chemistry, the synthesis of XeF5(-) ... |
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