A Base-Assisted One-Pot Cyclization and Potassium Association Route to a Very Thermally Stable Bistetrazole Salt

Abstract

Pursuing next-generation energetic materials has prompted researchers to investigate novel combinations of structural and energetic properties. In this study, we constructed a coordination-driven bisnitroimino-tetrazole scaffold, dipotassium 1,1′-methylene bis(1-nitroimino tetrazolate) (K₂MBNIT), which exhibits ultra-high thermal stability, remarkably surpassing the thermal performance of previously reported bistetrazole-based potassium salts such as K₂DNABT (potassium 4,5-bis(dinitromethyl)furoxannate) and K₂ABNAT (5,5′-azobis(1-nitroimino tetrazolate). The synthetic route to K₂MBNIT features two key transformations: an initial tetrazole ring opening and a subsequent ring-closing reaction to form the final bistetrazole structure. In the cyclization step, K₂MBNIT is selectively obtained from the unprecedently formed precursor, 1,1′-methylene bis(1-azido-1-nitroiminomethylene) (4). K₂MBNIT exhibits a decomposition temperature comparable to heat-resistant energetic materials and sensitivity akin to primary explosives, presenting a unique combination of desirable properties for modern applications such as hypersonic weapons, space missions, and deep-well drilling. The straightforward synthetic methodology, methylene-assisted structural stabilization, and superior heat resistance collectively highlight K₂MBNIT as a promising candidate for a next-generation energetic material.