3,6‐Di(azido)‐1,2,4,5‐Tetrazine: A Precursor for the Preparation of Carbon Nanospheres and Nitrogen‐Rich Carbon Nitrides

Abstract

Microbead and nanophase carbon materials attract many researchers due to their unique applications, [1] which include high-density and high-strength carbon artifacts, [2] super-active carbon beads of high surface area, [3] lithium storage, [4a] lithium battery anodes, [4b-d] spherical packing materials for HPLC, [5] hydrogen storage applications, [6] and catalysis. [7] Much attention has focused on the preparation (precursors and methods) and properties of these carbon materials, because their applications significantly depend on the shape and size of the particles.Carbon nitrides are of current interest due to their novel mechanical, optical, and tribological properties, including low density, extreme hardness, surface roughness, wear resistance, chemical inertness, and biocompatibility.[8] These superhard diamondlike materials promise a variety of technological and biological applications. For example, they are used as biocompatible coatings on biomedical implants, [8][9] battery electrodes, [10] catalytic supports, [11] gas separation systems, [12] electronic materials, [13] and humidity and gas sensors.[14]Unlike carbon-based materials, applications of carbon nitrides are not only governed by the texture and size of the particles [13] but also by the relative nitrogen content. As a consequence, an extensive effort has focused on the discovery of precursors along with the appropriate methods to increase the nitrogen content in carbon nitrides.There is very little literature on the preparation of carbon nanospheres and nitrogen-rich carbon nitrides (> 60 wt % N). Gillan reported preparations of carbon nitrides C 3 N 4 (60.9 wt % N) and C 3 N 5 (66.0 wt % N) and graphitic carbon using high-nitrogen 2,4,6-tri(azido)-1,3,5-triazine as the pre-

Azide–Tetrazole Ring‐Chain Isomerism in Polyazido‐1,3,5‐triazines, Triazido‐s‐heptazine, and Diazidotetrazines

“…This explains the experimentally observed shift to the azide compounds with a decreasing solvent polarity, which was observed for example for thiazole [3,2-d]tetrazole [15] and diazidotetrazine. [21] The PCM calculations for CCl 4 , DMSO, and water also indicate that more polar solvents favor the tetrazoles. The ground states are influenced more by solvation than the ground states.…”

“…Their clean and thermodynamically favorable decomposition, where only N 2 is released, makes them good precursors for nitrogen rich carbon nitrides, whose application is not only governed by texture and size of the particles, [2] but also by the relative nitrogen content. Nitrogen-rich carbon nitrides with the bulk formulas C 3 N 4 and C 3 N 5 have been prepared from cyanuric azide [3] as well as bis(azido)-1,2,4,5-tetrazine [4] and nitrides with the formulas C 2 N 3 and C 3 N 5 have been prepared from tetra(azido)azo-1,3,5-triazine. [5] Unfortunately, all described polyazides are very sensitive toward shock and friction and are classified as primary explosives.…”

“…We also in- vestigated the recently synthesized azo-and hydrazobridged dimers [5,22] of bis(azido)-1,3,5-triazine as well as triazido-s-heptazine. [23] The same calculations were also performed for several polyazido-1,2,4,5-tetrazines: bis(azido)-tetrazine [4] and the yet unknown azo-and hydrazo-bridged dimers of azidotetrazine.…”

Six‐Membered Heterocycles: Triazines, Tetrazines and Other Polyaza Systems

“…3,6-Diethyl-1,2,4,5-tetrazine has been employed as unique solvatochromic probe in the Solvent Acidity Scale [756]. 3,6-Diazido-1,2,4,5-tetrazine has been synthesized for the preparation of carbon nanospheres and nitrogen-rich carbon nitrides [757]. Only recent synthetic methods of tetrazines are commented on here.…”

“…The electron-deficient aromatic ring of tetrazine and its reactivity towards nucleophiles have been utilized in the preparation of non-symmetrically substituted tetrazines by substitution of leaving groups, such as chloro [770,771], methylthio [770,[772][773][774][775] or dimethylpyridazolyl [755,757,776,777] with nitrogen, oxygen or sulfur nucleophiles. The use of carbon nucleophiles, such as organolithium or Grignard reagents, with 3,6-disubstituted 1,2,4,5-tetrazines 368 led to the addition of an organic group onto a ring nitrogen atom to afford 1,4-dihydrotetrazines 369 [778] (Scheme 20.109).…”