Arylpentazoles with surprisingly high kinetic stability

Bo, Xiaoxu; Dong, Zhiyong; Ye, Ding

doi:10.1039/d1cc01793d

Cited by 11 publications

(8 citation statements)

References 52 publications

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“…It has been suggested that an ideal HEDM would have a free-energy activation barrier of ∼30 kcal mol –1 with a half-life of ∼35 years at room temperature . Recently, it has been proposed via CBS–QB3 calculations that it is possible to achieve this level of kinetic stability for arylpentazole by substituting Lewis acids at the ortho positions of the aryl ring . While this has yet to be accomplished experimentally and the size of the molecules makes them cost prohibitive to study with high-level ab inito methods, it would significantly increase the utility of pentazole derivatives by making them safer and easier to work with and store.…”

Section: Introductionmentioning

confidence: 99%

“…6 Recently, it has been proposed via CBS−QB3 calculations that it is possible to achieve this level of kinetic stability for arylpentazole by substituting Lewis acids at the ortho positions of the aryl ring. 39 While this has yet to be accomplished experimentally and the size of the molecules makes them cost prohibitive to study with high-level ab inito methods, it would significantly increase the utility of pentazole derivatives by making them safer and easier to work with and store. However, this would be difficult to achieve for the parent pentazole or one of its simpler derivatives without external influences, though it is possible that a pentazole compound could become moderately stable at a lower temperature.…”

Section: ■ Introductionmentioning

confidence: 99%

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Kinetic Stability of Pentazole

et al. 2021

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The utility of high energy density materials (HEDMs) comes from their thermodynamic properties which arise from specific structural features that contribute to energy storage. Studies of such structural features seek to increase our understanding of these energy storage mechanisms in order to further enhance their properties. High-nitrogen-containing HEDMs are of particular interest because they are less toxic than traditional HEDMs. Pentazole is the largest of the nitrogen rings which has been synthesized and considered for an HEDM; however, few experimental studies exist due to the difficulty involved in the synthesis, and most previous theoretical studies employed composite methods where lower level geometries were used with higher level methods. Here, the decomposition reaction of pentazole is studied. Geometries, fundamental frequencies, and energies for each of the stationary points of the decomposition pathway are computed using ab initio methods up to CCSDT(Q). Decomposition rates are calculated over a range of temperatures using canonical transition state theory in order to determine the kinetic stability of pentazole. Based on the present results, it would be difficult for pentazole to act as an HEDM, requiring temperatures close to 200 K to achieve a suitable level of stability.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Kinetic Stability of Pentazole

et al. 2021

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“…costabilization method and host-guest strategy). [60][61][62] Single-crystal X-ray diffraction studies showed that cyclo-N 5…”

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confidence: 99%

Pentazolate Anion: A Rare and Preferred Five‐Membered Ligand for Constructing Pentasil‐Zeolite Topology Architectures

Cao,

Liu,

Zhang

2024

Angewandte Chemie

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As the fourth full‐nitrogen structure, the pentazolate anion (cyclo‐N5−) was highly coveted for decades. In 2017, the first air‐stable non‐metal pentazolate salt, (N5)6(H3O)3(NH4)4Cl, was obtained, representing a milestone in this field. As the latest member of the azole family, cyclo‐N5− is comprised of five nitrogen atoms. Although significant attention has been paid to the potential of cyclo‐N5− as an energetic material, its poor thermostability hinders any practical application. However, the unique ring structure and multiple coordination capability of cyclo‐N5− provide a platform for the fabrication of various structures, among which pentasil‐zeolite topologies are the most intriguing. In addition, the introduction of structure‐directing auxiliaries enables the self‐assembly of diverse topological architectures, potentially imparting cyclo‐N5− with the potential to impact wide‐ranging areas of coordination chemistry and topology. In this minireview, different pentasil‐zeolite topologies based on metal‐pentazolate frameworks are evaluated. To date, three zeolitic and zeolite‐like topologies have been reported, namely the melanophlogite (MEP), chibaite (MTN), and unj topologies. The MEP topology consists of two nanocages, Na20N60 and Na24N60, whereas the MTN topology contains Na20N60 and Na28N80 nanocages. Furthermore, the unj topology features multiple homochiral channels consisting of two helical chains. Various possible strategies for obtaining additional pentasil‐zeolite topologies are also discussed.

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“…Notably, the NPA charge in free and LA-stabilized 01 remains positive, in sharp contrast to all of the reported pentazoles (i.e., cyclo-RN 5 with R being a non-F substituent) with a negatively charged N 5 ring. We are aware that the gas phase ring-destruction barriers of a series of arylpentazoles (cyclo-ArN 5 ) were reported very recently to lie in the range of 17.71−20.89 kcal/mol at the CBS-QB3 level, 58 and most of these cyclo-ArN 5 species have been synthesized (though need to be stored at low temperatures 63 ). Thus, we anticipated that both free and LAattached 01 with barriers of 13−23 kcal/mol and large BDEs (see Table S4.4) could have a great likelihood of being synthesized in the laboratory, either spectroscopically or even in the condensed phase.…”

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confidence: 99%

“…Thus, cyclo -FN 5 is charge anomalous compared to nearly all pentazoles! Unfortunately, a number of theoretical studies have shown a reverse correlation between the ring-destruction stability of cyclo- RN 5 and the electronegativity of R, i.e., the larger electronegativity of R, the lower kinetic stability of cyclo- RN 5 . − Understandably, the F atom, the most electronegative element in the periodic table, should make cyclo -FN 5 bear the lowest ring-destruction barrier [6.70 kcal/mol at the CCSD(T)/aug-cc-pVDZ//MP2(full)/6-311G(d) level] . This is surely quite upset, because a low barrier is generally associated with a short lifetime.…”

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confidence: 99%

Free and Complexed Fluoropentazoles: Anomalous Ring Charge and Appreciable Kinetic Stability

Tian

2022

J. Phys. Chem. Lett.

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Fluoronitrogens are strongly related to high-energy density materials. Fluoropentazole (cyclo-FN5) with hitherto the highest N/F ratio at ambient pressure belongs to the family of well-known and 119-year-old pentazoles. Due to the presence of the overwhelmingly electronegative F element, cyclo-FN5 is the only pentazole to date that contains a cationic N5 ring. However, also due to F’s large electronegativity, the reported ring-destruction barrier of cyclo-FN5 is nearly the lowest (6.7 kcal/mol), which has made its synthesis and characterization quite difficult. Here, cyclo-FN5 was re-predicted to bear an almost doubled ring-destruction barrier (∼12–14 kcal/mol) at the CBS-QB3, G4, W1BD, CCSD(T)/CBS//CCSD/cc-pVTZ, and CCSD(T)/CBS//CCSD(T)/aug-cc-pVTZ levels. Promisingly, upon further complexation with Lewis acid(s), the ring-destruction barrier of cyclo-FN5 might reach 23 kcal/mol, which is comparable to that of the well-known and already synthesized arylpentazoles (∼20 kcal/mol), and the positive charge on the N5 ring can be increased to 0.66 |e|.

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Arylpentazoles with surprisingly high kinetic stability

Abstract: A co-stabilization method was proposed to design a series of novel arylpentazoles with very high N2-leaving barriers, one of which reached hitherto the highest value of 40.83 kcal mol−1 at the CBS-QB3 level.

Cited by 11 publications

References 52 publications

Kinetic Stability of Pentazole

Kinetic Stability of Pentazole

Pentazolate Anion: A Rare and Preferred Five‐Membered Ligand for Constructing Pentasil‐Zeolite Topology Architectures

Free and Complexed Fluoropentazoles: Anomalous Ring Charge and Appreciable Kinetic Stability

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