N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods... more N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods are reported for their larger scale production. A new, marginally stable N(2)F(+) salt, N(2)F(+)Sn(2)F(9)(-), was prepared and characterized. An ordered crystal structure was obtained for N(2)F(+)Sb(2)F(11)(-), resulting in the first observation of individual N[triple bond]N and N-F bond distances for N(2)F(+) in the solid phase. The observed N[triple bond]N and N-F bond distances of 1.089(9) and 1.257(8) A, respectively, are among the shortest experimentally observed N-N and N-F bonds. High-level electronic structure calculations at the CCSD(T) level with correlation-consistent basis sets extrapolated to the complete basis limit show that cis-N(2)F(2) is more stable than trans-N(2)F(2) by 1.4 kcal/mol at 298 K. The calculations also demonstrate that the lowest uncatalyzed pathway for the trans-cis isomerization of N(2)F(2) has a barrier of 60 kcal/mol and involves rotation about the N=N double bond. This barrier is substantially higher than the energy required for the dissociation of N(2)F(2) to N(2) and 2 F. Therefore, some of the N(2)F(2) dissociates before undergoing an uncatalyzed isomerization, with some of the dissociation products probably catalyzing the isomerization. Furthermore, it is shown that the trans-cis isomerization of N(2)F(2) is catalyzed by strong Lewis acids, involves a planar transition state of symmetry C(s), and yields a 9:1 equilibrium mixture of cis-N(2)F(2) and trans-N(2)F(2). Explanations are given for the increased reactivity of cis-N(2)F(2) with Lewis acids and the exclusive formation of cis-N(2)F(2) in the reaction of N(2)F(+) with F(-). The geometry and vibrational frequencies of the F(2)N=N isomer have also been calculated and imply strong contributions from ionic N(2)F(+) F(-) resonance structures, similar to those in F(3)NO and FNO.
N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods... more N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods are reported for their larger scale production. A new, marginally stable N(2)F(+) salt, N(2)F(+)Sn(2)F(9)(-), was prepared and characterized. An ordered crystal structure was obtained for N(2)F(+)Sb(2)F(11)(-), resulting in the first observation of individual N[triple bond]N and N-F bond distances for N(2)F(+) in the solid phase. The observed N[triple bond]N and N-F bond distances of 1.089(9) and 1.257(8) A, respectively, are among the shortest experimentally observed N-N and N-F bonds. High-level electronic structure calculations at the CCSD(T) level with correlation-consistent basis sets extrapolated to the complete basis limit show that cis-N(2)F(2) is more stable than trans-N(2)F(2) by 1.4 kcal/mol at 298 K. The calculations also demonstrate that the lowest uncatalyzed pathway for the trans-cis isomerization of N(2)F(2) has a barrier of 60 kcal/mol and involves rotation about the N=...
Diphenylaminodiazidophosphane (C6H5)2NP(N3)2 was synthesized from the corresponding dihalides (C6... more Diphenylaminodiazidophosphane (C6H5)2NP(N3)2 was synthesized from the corresponding dihalides (C6H5)2NPX2 (X = F, Cl) and (CH3)3SiN3, and was characterized by vibrational and multinuclear NMR spectroscopy. The intermediate compound (C6H5)2NPF(N3) was also observed by NMR spectroscopy in solution. Some physical properties and reactions of all these compounds are discussed.
Two ammonia-(dinitramido)boranes were synthesized by the reaction of dinitroamine with ammonia-bo... more Two ammonia-(dinitramido)boranes were synthesized by the reaction of dinitroamine with ammonia-borane. These compounds are the first reported examples of (dinitramido)boranes. Ammonia-mono(dinitramido)borane is a perfectly oxygen-balanced high-energy-density material (HEDM) composed of an ammonia-BH2 fuel group and a strongly oxidizing dinitramido ligand. Although it is thermally not stable enough for practical applications, its predicted specific impulse as a solid rocket propellant would be 333 s. Its predicted performance as an explosive matches that of pentaerythtritol tetranitrate (PETN) and significantly exceeds that of trinitrotoluene (TNT). Its structure was established by X-ray crystallography and vibrational and multinuclear NMR spectroscopy. Additionally, the over-oxidized ammoniabis(dinitramido)borane was detected by NMR spectroscopy.
Angewandte Chemie (International ed. in English), Jan 19, 2015
NF3 and N(NO2)3 are known compounds, whereas the mixed fluoronitroamines, FN(NO2)2 and F2NNO2, ha... more NF3 and N(NO2)3 are known compounds, whereas the mixed fluoronitroamines, FN(NO2)2 and F2NNO2, have been unknown thus far. One of these, FN(NO2)2, has now been prepared and characterized by multinuclear NMR and Raman spectroscopy. FN(NO2)2 is the first known example of an inorganic fluoronitroamine. It is a thermally unstable, highly energetic material formed by the fluorination of the dinitramide anion using NF4(+) salts as the preferred fluorinating agent.
ABSTRACT The elusive nitryl cyanide, NCNO2, has been synthesized and characterized. It was prepar... more ABSTRACT The elusive nitryl cyanide, NCNO2, has been synthesized and characterized. It was prepared in good yield, isolated by fractional condensation, characterized by NMR and vibrational spectroscopy, and studied by theoretical calculations. Nitryl cyanide holds promise as a high energy density material (HEDM) and might also prove useful as a HEDM building block. The simplicity and inherent stability of nitryl cyanide, together with the known multitude of nitriles in interstellar space, suggest that the compound might also be a potential candidate for observations in atmospheric and interstellar chemistry.
ABSTRACT Compounds (IVa—f) (syntheses yields given in g) are characterized by single crystal XRD,... more ABSTRACT Compounds (IVa—f) (syntheses yields given in g) are characterized by single crystal XRD, Raman spectroscopy, and DFT calculations.
The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylat... more The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylation reactions. However, for more than six decades, the trifluoromethanide anion was widely believed to exist only as a short-lived transient species in the condensed phase. It has now been prepared in bulk for the first time in THF solution. The trifluoromethanide anion with the [K(18-crown-6)](+) cation was unequivocally characterized by low-temperature (19)F and (13)C NMR spectroscopy. Its intermediacy in nucleophilic trifluoromethylation reactions was directly evident by its reaction chemistry with various electrophilic substrates. Variable-temperature NMR spectroscopy, along with quantum mechanical calculations, support the persistence of the trifluoromethanide anion.
The new N 5 + salt, N 5 + SbF 6 - , was prepared from N 2 F + SbF 6 - and HN 3 in anhydrous HF so... more The new N 5 + salt, N 5 + SbF 6 - , was prepared from N 2 F + SbF 6 - and HN 3 in anhydrous HF solution. The white solid is surprisingly stable, decomposing only at 70 °C, and is relatively insensitive to impact. Its vibrational spectrum exhibits all nine fundamentals with ...
N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods... more N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods are reported for their larger scale production. A new, marginally stable N(2)F(+) salt, N(2)F(+)Sn(2)F(9)(-), was prepared and characterized. An ordered crystal structure was obtained for N(2)F(+)Sb(2)F(11)(-), resulting in the first observation of individual N[triple bond]N and N-F bond distances for N(2)F(+) in the solid phase. The observed N[triple bond]N and N-F bond distances of 1.089(9) and 1.257(8) A, respectively, are among the shortest experimentally observed N-N and N-F bonds. High-level electronic structure calculations at the CCSD(T) level with correlation-consistent basis sets extrapolated to the complete basis limit show that cis-N(2)F(2) is more stable than trans-N(2)F(2) by 1.4 kcal/mol at 298 K. The calculations also demonstrate that the lowest uncatalyzed pathway for the trans-cis isomerization of N(2)F(2) has a barrier of 60 kcal/mol and involves rotation about the N=N double bond. This barrier is substantially higher than the energy required for the dissociation of N(2)F(2) to N(2) and 2 F. Therefore, some of the N(2)F(2) dissociates before undergoing an uncatalyzed isomerization, with some of the dissociation products probably catalyzing the isomerization. Furthermore, it is shown that the trans-cis isomerization of N(2)F(2) is catalyzed by strong Lewis acids, involves a planar transition state of symmetry C(s), and yields a 9:1 equilibrium mixture of cis-N(2)F(2) and trans-N(2)F(2). Explanations are given for the increased reactivity of cis-N(2)F(2) with Lewis acids and the exclusive formation of cis-N(2)F(2) in the reaction of N(2)F(+) with F(-). The geometry and vibrational frequencies of the F(2)N=N isomer have also been calculated and imply strong contributions from ionic N(2)F(+) F(-) resonance structures, similar to those in F(3)NO and FNO.
N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods... more N(2)F(+) salts are important precursors in the synthesis of N(5)(+) compounds, and better methods are reported for their larger scale production. A new, marginally stable N(2)F(+) salt, N(2)F(+)Sn(2)F(9)(-), was prepared and characterized. An ordered crystal structure was obtained for N(2)F(+)Sb(2)F(11)(-), resulting in the first observation of individual N[triple bond]N and N-F bond distances for N(2)F(+) in the solid phase. The observed N[triple bond]N and N-F bond distances of 1.089(9) and 1.257(8) A, respectively, are among the shortest experimentally observed N-N and N-F bonds. High-level electronic structure calculations at the CCSD(T) level with correlation-consistent basis sets extrapolated to the complete basis limit show that cis-N(2)F(2) is more stable than trans-N(2)F(2) by 1.4 kcal/mol at 298 K. The calculations also demonstrate that the lowest uncatalyzed pathway for the trans-cis isomerization of N(2)F(2) has a barrier of 60 kcal/mol and involves rotation about the N=...
Diphenylaminodiazidophosphane (C6H5)2NP(N3)2 was synthesized from the corresponding dihalides (C6... more Diphenylaminodiazidophosphane (C6H5)2NP(N3)2 was synthesized from the corresponding dihalides (C6H5)2NPX2 (X = F, Cl) and (CH3)3SiN3, and was characterized by vibrational and multinuclear NMR spectroscopy. The intermediate compound (C6H5)2NPF(N3) was also observed by NMR spectroscopy in solution. Some physical properties and reactions of all these compounds are discussed.
Two ammonia-(dinitramido)boranes were synthesized by the reaction of dinitroamine with ammonia-bo... more Two ammonia-(dinitramido)boranes were synthesized by the reaction of dinitroamine with ammonia-borane. These compounds are the first reported examples of (dinitramido)boranes. Ammonia-mono(dinitramido)borane is a perfectly oxygen-balanced high-energy-density material (HEDM) composed of an ammonia-BH2 fuel group and a strongly oxidizing dinitramido ligand. Although it is thermally not stable enough for practical applications, its predicted specific impulse as a solid rocket propellant would be 333 s. Its predicted performance as an explosive matches that of pentaerythtritol tetranitrate (PETN) and significantly exceeds that of trinitrotoluene (TNT). Its structure was established by X-ray crystallography and vibrational and multinuclear NMR spectroscopy. Additionally, the over-oxidized ammoniabis(dinitramido)borane was detected by NMR spectroscopy.
Angewandte Chemie (International ed. in English), Jan 19, 2015
NF3 and N(NO2)3 are known compounds, whereas the mixed fluoronitroamines, FN(NO2)2 and F2NNO2, ha... more NF3 and N(NO2)3 are known compounds, whereas the mixed fluoronitroamines, FN(NO2)2 and F2NNO2, have been unknown thus far. One of these, FN(NO2)2, has now been prepared and characterized by multinuclear NMR and Raman spectroscopy. FN(NO2)2 is the first known example of an inorganic fluoronitroamine. It is a thermally unstable, highly energetic material formed by the fluorination of the dinitramide anion using NF4(+) salts as the preferred fluorinating agent.
ABSTRACT The elusive nitryl cyanide, NCNO2, has been synthesized and characterized. It was prepar... more ABSTRACT The elusive nitryl cyanide, NCNO2, has been synthesized and characterized. It was prepared in good yield, isolated by fractional condensation, characterized by NMR and vibrational spectroscopy, and studied by theoretical calculations. Nitryl cyanide holds promise as a high energy density material (HEDM) and might also prove useful as a HEDM building block. The simplicity and inherent stability of nitryl cyanide, together with the known multitude of nitriles in interstellar space, suggest that the compound might also be a potential candidate for observations in atmospheric and interstellar chemistry.
ABSTRACT Compounds (IVa—f) (syntheses yields given in g) are characterized by single crystal XRD,... more ABSTRACT Compounds (IVa—f) (syntheses yields given in g) are characterized by single crystal XRD, Raman spectroscopy, and DFT calculations.
The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylat... more The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylation reactions. However, for more than six decades, the trifluoromethanide anion was widely believed to exist only as a short-lived transient species in the condensed phase. It has now been prepared in bulk for the first time in THF solution. The trifluoromethanide anion with the [K(18-crown-6)](+) cation was unequivocally characterized by low-temperature (19)F and (13)C NMR spectroscopy. Its intermediacy in nucleophilic trifluoromethylation reactions was directly evident by its reaction chemistry with various electrophilic substrates. Variable-temperature NMR spectroscopy, along with quantum mechanical calculations, support the persistence of the trifluoromethanide anion.
The new N 5 + salt, N 5 + SbF 6 - , was prepared from N 2 F + SbF 6 - and HN 3 in anhydrous HF so... more The new N 5 + salt, N 5 + SbF 6 - , was prepared from N 2 F + SbF 6 - and HN 3 in anhydrous HF solution. The white solid is surprisingly stable, decomposing only at 70 °C, and is relatively insensitive to impact. Its vibrational spectrum exhibits all nine fundamentals with ...
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Papers by Karl OChriste