Energetic High-Nitrogen Compounds: 5‑(Trinitromethyl)‑2<i>H</i>‑tetrazole and -tetrazolates, Preparation, Characterization, and Conversion into 5‑(Dinitromethyl)tetrazoles

A convenient access to 5-(trinitromethyl)-2<i>H</i>-tetrazole (HTNTz) has been developed, based on the exhaustive nitration of 1<i>H</i>-tetrazole-5-acetic acid, which was prepared from ethyl cyanoacetate and HN₃ in a 1,3-dipolar cycloaddition reaction, followed by basic hydrolysis. HTNTz was converted into the ammonium, guanidinium, rubidium, cesium, copper, and silver 5-(trinitromethyl)-2<i>H</i>-tetrazolates. In addition, the ammonia adducts of the copper and silver salts were isolated. The reaction of HTNTz with hydrazine and hydroxylamine resulted in the formation of hydrazinium 5-(dinitromethyl)­tetrazolate and hydroxylammonium 5-(dinitromethyl)-1<i>H</i>-tetrazolate, respectively. Acid treatment of both 5-(dinitromethyl)­tetrazolates resulted in the isolation of 5-(dinitromethylene)-4,5-dihydro-1<i>H</i>-tetrazole, which was converted into potassium 5-(dinitromethyl)-1<i>H</i>-tetrazolate by reaction with K₂CO₃. All prepared compounds were fully characterized by ¹H, ¹³C, ¹⁴N, and ¹⁵N NMR spectroscopy and X-ray crystal structure determination. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (differential thermal analysis, DTA) were also carried out. The 5-(trinitromethyl) and 5-(dinitromethyl)­tetrazoles are highly energetic materials that explode upon impact or heating

Energetic High-Nitrogen Compounds: 5‑(Trinitromethyl)‑2<i>H</i>‑tetrazole and -tetrazolates, Preparation, Characterization, and Conversion into 5‑(Dinitromethyl)tetrazoles

A convenient access to 5-(trinitromethyl)-2<i>H</i>-tetrazole (HTNTz) has been developed, based on the exhaustive nitration of 1<i>H</i>-tetrazole-5-acetic acid, which was prepared from ethyl cyanoacetate and HN₃ in a 1,3-dipolar cycloaddition reaction, followed by basic hydrolysis. HTNTz was converted into the ammonium, guanidinium, rubidium, cesium, copper, and silver 5-(trinitromethyl)-2<i>H</i>-tetrazolates. In addition, the ammonia adducts of the copper and silver salts were isolated. The reaction of HTNTz with hydrazine and hydroxylamine resulted in the formation of hydrazinium 5-(dinitromethyl)­tetrazolate and hydroxylammonium 5-(dinitromethyl)-1<i>H</i>-tetrazolate, respectively. Acid treatment of both 5-(dinitromethyl)­tetrazolates resulted in the isolation of 5-(dinitromethylene)-4,5-dihydro-1<i>H</i>-tetrazole, which was converted into potassium 5-(dinitromethyl)-1<i>H</i>-tetrazolate by reaction with K₂CO₃. All prepared compounds were fully characterized by ¹H, ¹³C, ¹⁴N, and ¹⁵N NMR spectroscopy and X-ray crystal structure determination. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (differential thermal analysis, DTA) were also carried out. The 5-(trinitromethyl) and 5-(dinitromethyl)­tetrazoles are highly energetic materials that explode upon impact or heating

Energetic High-Nitrogen Compounds: 5‑(Trinitromethyl)‑2<i>H</i>‑tetrazole and -tetrazolates, Preparation, Characterization, and Conversion into 5‑(Dinitromethyl)tetrazoles

A convenient access to 5-(trinitromethyl)-2<i>H</i>-tetrazole (HTNTz) has been developed, based on the exhaustive nitration of 1<i>H</i>-tetrazole-5-acetic acid, which was prepared from ethyl cyanoacetate and HN₃ in a 1,3-dipolar cycloaddition reaction, followed by basic hydrolysis. HTNTz was converted into the ammonium, guanidinium, rubidium, cesium, copper, and silver 5-(trinitromethyl)-2<i>H</i>-tetrazolates. In addition, the ammonia adducts of the copper and silver salts were isolated. The reaction of HTNTz with hydrazine and hydroxylamine resulted in the formation of hydrazinium 5-(dinitromethyl)­tetrazolate and hydroxylammonium 5-(dinitromethyl)-1<i>H</i>-tetrazolate, respectively. Acid treatment of both 5-(dinitromethyl)­tetrazolates resulted in the isolation of 5-(dinitromethylene)-4,5-dihydro-1<i>H</i>-tetrazole, which was converted into potassium 5-(dinitromethyl)-1<i>H</i>-tetrazolate by reaction with K₂CO₃. All prepared compounds were fully characterized by ¹H, ¹³C, ¹⁴N, and ¹⁵N NMR spectroscopy and X-ray crystal structure determination. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (differential thermal analysis, DTA) were also carried out. The 5-(trinitromethyl) and 5-(dinitromethyl)­tetrazoles are highly energetic materials that explode upon impact or heating

Unprecedented Conformational Variability in Main Group Inorganic Chemistry: the Tetraazidoarsenite and -Antimonite Salts A⁺[M(N₃)₄]⁻ (A = NMe₄, PPh₄, (Ph₃P)₂N; M = As, Sb), Five Similar Salts, Five Different Anion Structures

A unique example for conformational variability in inorganic main group chemistry has been discovered. The arrangement of the azido ligands in the pseudotrigonal bipyramidal [As­(N₃)₄]⁻ and [Sb­(N₃)₄]⁻ anions theoretically can give rise to seven different conformers which have identical MN₄ skeletons but different azido ligand arrangements and very similar energies. We have now synthesized and structurally characterized five of these conformers by subtle variations in the nature of the counterion. Whereas conformational variability is common in organic chemistry, it is rare in inorganic main group chemistry and is usually limited to two. To our best knowledge, the experimental observation of five distinct single conformers for the same type of anion is unprecedented. Theoretical calculations at the M06-2X/cc-pwCVTZ-PP level for all seven possible basic conformers show that (1) the energy differences between the five experimentally observed conformers are about 1 kcal/mol or less, and (2) the free monomeric anions are the energetically favored species in the gas phase and also for [As­(N₃)₄]⁻ in the solid state, whereas for [Sb­(N₃)₄]⁻ associated anions are energetically favored in the solid state and possibly in solutions. Raman spectroscopy shows that in the azide antisymmetric stretching region, the solid-state spectra are distinct for the different conformers, and permits their identification. The spectra of solutions are solvent dependent and differ from those of the solids indicating the presence of rapidly exchanging equilibria of different conformers. The only compound for which a solid with a single well-ordered conformer could not be isolated was [N­(CH₃)₄]­[As­(N₃)₄] which formed a viscous, room-temperature ionic liquid. Its Raman spectrum was identical to that of its CH₃CN solution indicating the presence of an equilibrium of multiple conformers

Energetic Bis(3,5-dinitro‑1<i>H</i>‑1,2,4-triazolyl)dihydro- and dichloroborates and Bis(5-nitro‑2<i>H</i>‑tetrazolyl)‑, Bis(5-(trinitromethyl)‑2<i>H</i>‑tetrazolyl)‑, and Bis(5-(fluorodinitromethyl)‑2<i>H</i>‑tetrazolyl)dihydroborate

Salts of bis­(3,5-dinitro-1<i>H</i>-1,2,4-triazolyl)­dihydro- and dichloroborate and bis­(5-nitro-2<i>H</i>-tetrazolyl)-, bis­(5-trinitromethyl-2<i>H</i>-tetrazolyl)-, and bis­(5-fluorodinitromethyl-2<i>H</i>-tetrazolyl)­dihydroborate anions have been synthesized by the treatment of hydroborates or chloroborates with the corresponding nitroazoles or nitroazolates, respectively. Alkali-metal salts of these dihydroborates are energetic and can be shock-sensitive, while salts with larger organic cations, such as NMe₄⁺, PPh₄⁺, or (Ph₃P)₂N⁺, are less sensitive. Poly­(nitroazolyl)­borates are promising candidates for a new class of environmentally benign energetic materials and high-oxygen carriers

Syntheses of Diphenylaminodiazidophosphane and Diphenylaminofluoroazidophosphane

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

Binary Group 15 Polyazides. Structural Characterization of [Bi(N₃)₄]⁻, [Bi(N₃)₅]^2–, [bipy·Bi(N₃)₅]^2–, [Bi(N₃)₆]^3–, bipy·As(N₃)₃, bipy·Sb(N₃)₃, and [(bipy)₂·Bi(N₃)₃]₂ and on the Lone Pair Activation of Valence Electrons

The binary group 15 polyazides As(N₃)₃, Sb(N₃)₃, and Bi(N₃)₃ were stabilized by either anion or donor−acceptor adduct formation. Crystal structures are reported for [Bi(N₃)₄]^–, [Bi(N₃)₅]^2–, [bipy·Bi(N₃)₅]^2–, [Bi(N₃)₆]^3–, bipy·As(N₃)₃, bipy·Sb(N₃)₃, and [(bipy)₂·Bi(N₃)₃]₂. The lone valence electron pair on the central atom of these pnictogen(+III) compounds can be either sterically active or inactive. The [Bi(N₃)₅]^2– anion possesses a sterically active lone pair and a monomeric pseudo-octahedral structure with a coordination number of 6, whereas its 2,2′-bipyridine adduct exhibits a pseudo-monocapped trigonal prismatic structure with CN 7 and a sterically inactive lone pair. Because of the high oxidizing power of Bi(+V), reactions aimed at Bi(N₃)₅ and [Bi(N₃)₆]^– resulted in the reduction to bismuth(+III) compounds by [N₃]^–. The powder X-ray diffraction pattern of Bi(N₃)₃ was recorded at 298 K and is distinct from that calculated for Sb(N₃)₃ from its single-crystal data at 223 K. The [(bipy)₂·Bi(N₃)₃]₂ adduct is dimeric and derived from two BiN₈ square antiprisms sharing an edge consisting of two μ^1,1-bridging N₃ ligands and with bismuth having CN 8 and a sterically inactive lone pair. The novel bipy·As(N₃)₃ and bipy·Sb(N₃)₃ adducts are monomeric and isostructural and contain a sterically active lone pair on their central atom and a CN of 6. A systematic quantum chemical analysis of the structures of these polyazides suggests that the M06-2X density functional is well suited for the prediction of the steric activity of lone pairs in main-group chemistry. Furthermore, it was found that the solid-state structures can strongly differ from those of the free gas-phase species or those in solutions and that lone pairs that are sterically inactive in a chemical surrounding can become activated in the free isolated species

Binary Group 15 Polyazides. Structural Characterization of [Bi(N₃)₄]⁻, [Bi(N₃)₅]^2–, [bipy·Bi(N₃)₅]^2–, [Bi(N₃)₆]^3–, bipy·As(N₃)₃, bipy·Sb(N₃)₃, and [(bipy)₂·Bi(N₃)₃]₂ and on the Lone Pair Activation of Valence Electrons

The binary group 15 polyazides As(N₃)₃, Sb(N₃)₃, and Bi(N₃)₃ were stabilized by either anion or donor−acceptor adduct formation. Crystal structures are reported for [Bi(N₃)₄]^–, [Bi(N₃)₅]^2–, [bipy·Bi(N₃)₅]^2–, [Bi(N₃)₆]^3–, bipy·As(N₃)₃, bipy·Sb(N₃)₃, and [(bipy)₂·Bi(N₃)₃]₂. The lone valence electron pair on the central atom of these pnictogen(+III) compounds can be either sterically active or inactive. The [Bi(N₃)₅]^2– anion possesses a sterically active lone pair and a monomeric pseudo-octahedral structure with a coordination number of 6, whereas its 2,2′-bipyridine adduct exhibits a pseudo-monocapped trigonal prismatic structure with CN 7 and a sterically inactive lone pair. Because of the high oxidizing power of Bi(+V), reactions aimed at Bi(N₃)₅ and [Bi(N₃)₆]^– resulted in the reduction to bismuth(+III) compounds by [N₃]^–. The powder X-ray diffraction pattern of Bi(N₃)₃ was recorded at 298 K and is distinct from that calculated for Sb(N₃)₃ from its single-crystal data at 223 K. The [(bipy)₂·Bi(N₃)₃]₂ adduct is dimeric and derived from two BiN₈ square antiprisms sharing an edge consisting of two μ^1,1-bridging N₃ ligands and with bismuth having CN 8 and a sterically inactive lone pair. The novel bipy·As(N₃)₃ and bipy·Sb(N₃)₃ adducts are monomeric and isostructural and contain a sterically active lone pair on their central atom and a CN of 6. A systematic quantum chemical analysis of the structures of these polyazides suggests that the M06-2X density functional is well suited for the prediction of the steric activity of lone pairs in main-group chemistry. Furthermore, it was found that the solid-state structures can strongly differ from those of the free gas-phase species or those in solutions and that lone pairs that are sterically inactive in a chemical surrounding can become activated in the free isolated species