Synthesis, characterization, and comparison of explosive hexaamminecobalt(III) and nitropentamminecobalt(III) cyclopentazolate (cyclo‐N₅−) salts

Abstract

Metal pentazolate hydrates have attracted attention because of the unique stabilization mechanisms of cyclo-N 5 À anions during crystal stacking. However, coordinated H 2 O molecules influence the stability of cyclo-N 5 À anion-containing salts, and the structure-property relationship of high-valent cobalt pentazolate salts has not been previously reported. Werner-type cobalt(III) cations that trap cyclo-N 5 À anions, a novel class of cyclo-N 5 À -based materials, were prepared and characterized by infrared spectroscopy, elemental analysis, electrospray ionization mass spectrometry, and thermogravimetry with differential scanning calorimetry. The [Co(NH 3 ) 5 (NO 2 )] 2 + cation was also introduced via metathesis reactions to compare the intermolecular interactions in its intriguing structures. Single-crystal Xray diffraction revealed extensive hydrogen bonding networks in hexaamminecobalt(III) and nitropentamminecobalt(III) cyclo-N 5À salts between cyclo-N 5 À anions and NH 3 ligands or nitro groups. In addition, [Co(NH 3 ) 6 (N 5 ) 3 ] (1) and [Co(NH 3 ) 5 (NO 2 )](N 5 ) 2 (2) exhibited relatively high nitrogen contents of 79.2 % and 67.9 %, respectively, and the impact sensitivities of 1 (IS = 5 J) and 2 (IS = 4 J) are comparable to that of lead azide.

A molecular dynamics simulation study of thermal transport in hydrazinium cyclo-pentazolate

“…Interestingly, our simulation suggests a crucial role of the interaction between cyclo-N − 5 , in regulating the thermal transport and improving the thermal conductivity in HCP. Such a decisive role of the (cyclo-N − 5 )-(cyclo-N − 5 ) interaction had also been reported in previous work [33] when analyzing the sensitivity for various CPSs. Certainly, our study may be extended to assess the thermal transport for other CPSs, which thus provides a useful theoretical scheme to judge the thermal safety level for this high energy material.…”