Crystals of the highly energetic material bis(3,4-diamino-1,2,4-triazolium) dinitramide (2) representing one of the thermally most stable dinitramide derivatives which is due to the insertion of the long disregarded bis(3,4-diamino-1,2,4-triazolium) cation. Received (in XXX, XXX) Xth xxx 201x, Accepted Xth XXXXXXXXX 201xDOI: xx.xxx/b000000x 5 4,4',5,5'-Tetraamino-3,3'-bi-1,2,4-triazole (1) was prepared in one step from commonly available starting materials. Compound 1 comprises two combined aromatic triazoles with four amino moieties resulting in a compound which has i) a high temperature stability, ii) a high heat of formation, iii) high density and iv) no sensitivity towards physical stimuli (friction, impact and electrostatic discharge). Interestingly the compound has never been considered as building block in the development of new energetic materials. Therefore 1 was investigated in detail as a potential new nitrogen-rich, temperature stable cation for synthesis of energetic ionic derivatives (2−13) as 10 environmentally benign explosives. The cation was combined mostly with oxygen-rich counter-anions such as dinitramide (2), 5nitrotetrazole-2-oxide (3), 5-nitrotetrazolate (4), nitrate (5), tetranitrobisimidazole (6), 5,5'-bitetrazole-1,1'-dioxide (7), 1,1'-dinitramino-5,5'-bitetrazolate (8), 5-nitriminotetrazolate (9), 1-methyl-5-nitriminotetrazolate (10), perchlorate (11), picrate (12), nitroformate (13). Compounds 2-10 and 13 were characterized by low temperature single-crystal X-ray diffraction. All compounds were investigated by NMR and vibrational (IR, Raman) spectroscopy, mass spectrometry and elemental analysis. The excellent thermal properties were 15 determined by differential thermal analysis (DTA). The sensitivities towards impact, friction, and electrical discharge were investigated using BAM standards and a small scale electrostatic discharge tester. The detonation parameters of those compounds without inclusion of crystal water (1-3, 5-8, 11 and 13) were calculated using the EXPLO5 (V6.02) code and calculated (CBS-4M) enthalpy of formation values. + ). They 65 strongly vary in their stability towards temperature and in their energetic performance. A common observed trend in simple nitrogen-rich cations is the decrease in temperature stability in the

A novel strategy for the design of energetic materials that uses fused amino-substituted triazoles as energetic building blocks is presented. The 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium (TATOT) motif can be incorporated into many ionic, nitrogen-rich materials to form salts with advantages such as remarkably high stability towards physical or mechanical stimuli, excellent calculated detonation velocity, and toxicity low enough to qualify them as "green explosives". Neutral TATOT can be synthesized in a convenient and inexpensive two-step protocol in high yield. To demonstrate the superior properties of TATOT, 13 ionic derivatives were synthesized and their chemical- and physicochemical properties (e.g., sensitivities towards impact, friction and electrostatic discharge) were investigated extensively. Low toxicity was demonstrated for neutral TATOT and its nitrate salt. Both are insensitive towards impact and friction and the nitrate salt combines outstanding thermal stability (decomposition temperature=280 °C) with promising calculated energetic values.

The nucleophilic addition to nitrogen in 3-monosubstituted s-tetrazines under mild conditions is reported, by using silyl-enol ethers as the nucleophiles and mediated by BF 3 . The preference for this azaphilic addition over the usually observed inverse electron demand Diels-Alder reactions was determined experimentally and evaluated theoretically. In this regard, the influence of the effect of BF 3 -coordination to s-tetrazines was investigated thoroughly. The substrate dependency of this unusual reaction was rationalized by determination of the activation barriers and on the basis of the activation strain model by employing density functional theory. Lastly, the decomposition of the unstable adducts was examined and an interesting rearrangement to a triazine derived structure was observed.

We report the synthesis and first characterisation of the novel chemical probe 3-bromotetrazine and establish its reactivity towards nucleophiles. This led to the synthesis of several novel classes of 3monosubstituted s-tetrazines. A remarkable functional group selectivity is observed and is utilised to site-selectively functionalise different complex molecules. The stability of 3-bromotetrazine under the reaction conditions facilitated the development of a protocol for protein functionalisation, which enabled a "minimal", bifunctional tetrazine unit as a bio-orthogonal handle for inverse electron demand Diels-Alder reactions. Additionally, a novel tetrazine-based chemical probe was developed and its application in the context of thiol-targeted natural product isolation and labelling of mammalian cells is demonstrated.

The glycoslated macrocyclic antibiotic fidaxomicin ( 1 , tiacumicin B, lipiarmycin A3) displays good to excellent activity against Gram-positive bacteria and was approved for the treatment of Clostridium difficile infections (CDI). Among the main limitations for this compound, its low water solubility impacts further clinical uses. We report on the synthesis of new fidaxomicin derivatives based on structural design and utilizing an operationally simple one-step protecting group-free preparative approach from the natural product. An increase in solubility of up to 25-fold with largely retained activity was observed. Furthermore, hybrid antibiotics were prepared that show improved antibiotic activities.

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A Ag-mediated Pd-catalyzed cross-coupling method for 3-bromo-1,2,4,5-tetrazine with boronic acids is presented. Electronic modification of the 1,1′-bis(diphenylphosphine)ferrocene (dppf) ligand was found to be crucial for good turnover. Using this fast method, a variety of alkyl-, heteroatom-, and halide-substituted aryland heteroaryl-tetrazines were prepared (29 examples, up to 87% yield).

<div><div><div><p>The nucleophilic addition to nitrogen in 3-monosubstituted s-tetrazines under mild conditions is reported, by using silyl-enol ethers as the nucleophiles and mediated by BF3. The preference for this azaphilic addition over the usually observed inverse electron demand Diels-Alder reactions was determined experimentally and evaluated theoretically. In this regard, the influence of the effect of BF3-coordination to s-tetrazines was investigated thoroughly. The substrate dependency of this unusual reaction was rationalized by determination of the activation barriers and on the basis of the activation strain model by employing density functional theory. Lastly, the decomposition of the unstable adducts was examined and an interesting rearrangement to a triazine derived structure was observed.</p></div></div></div>