Extreme oxygen-rich functionalization of pyrazine via bis(trinitromethyl) substitution.

The development of high-performance energetic materials that simultaneously achieve strong detonation performance, favorable oxygen balance, and sufficient thermal stability remains a central challenge. Guided by a molecular design strategy that integrates extreme oxygen-rich functionality into a compact heteroaromatic framework, we report, to our knowledge, the first bis(trinitromethyl)-substituted pyrazine, a six-membered heteroaromatic system bearing six nitro groups via two carbon-centered polynitro substituents. A systematic synthetic study enabled the preparation of a series of polynitro-substituted pyrazines (P2-P4), including 2,5-bis(dinitromethyl)pyrazine and 2,5-bis(fluorodinitromethyl)pyrazine, allowing direct evaluation of gem-dinitro versus trinitromethyl substitution. All experimentally realized compounds were characterized by multinuclear NMR, infrared spectroscopy, elemental analysis, DSC, and, for P2-P4, single-crystal X-ray diffraction. Physicochemical and energetic evaluations identify P4 as the best-balanced experimentally realized member of the series, combining high density (1.94 g cm-3), a near-zero oxygen balance (-4.2%), moderate thermal stability (133 °C), and moderate impact sensitivity (8 J). Energetic performance calculations using a unified EXPLO5 protocol indicate that P4 delivers the highest overall detonation performance within the experimentally realized series, with a detonation velocity of 9301 m s-1, a detonation pressure of 39.8 GPa, and a heat of detonation of 6150 kJ kg-1. Targeted theoretical analyses of the experimentally relevant bottlenecks in the P1 and P5 routes suggest that the non-isolation of P1 and P5 is consistent with intrinsic electronic and steric constraints associated with further oxygen-rich functionalization of this scaffold. Collectively, these results establish pyrazine as a viable six-membered platform for bis(trinitromethyl) substitution and delineate experimentally grounded, computationally supported design boundaries for extreme oxygen-rich functionalization.