New Polynitrogen Molecules -- Energetic Air as a Next-Generation Propellant?
Abstract
The identification, development, and formulation of new energetic materials for advanced rocket propulsion applications is an area of long-standing interest to the Air Force. The performance limits of currently used propellants have been reached, so new energetic compounds are required to significantly improve the ability of the warfighter to access and control space. Polynitrogen species such as the recently discovered N5+ cation are of interest as potential energetic ingredients in new propellant formulations. Conventional techniques for characterizing polynitrogens have relied heavily on costly and time-consuming experimental synthesis and characterization. The availability of HPC resources has significantly lessened the need for these more empirical approaches by enabling the application of reliable high-level quantum chemical calculations to predict important properties such as heats of formation, stabilities, mechanisms of formation and decomposition, and spectroscopic constants. A key advantage of using HPC in this regard is the ability to efficiently "screen" a large number of potential polynitrogen molecules and focus subsequent experimental efforts on just the most promising candidates. The structures, stabilities, vibrational frequencies, and infrared intensities of several potential synthetic precursors to new polynitrogen species have been computed using ab initio electronic structure theory, at the second order perturbation theory level (MP2, also known as MBPT(2)), using the 6-31G(d) valence double-zeta polarized basis set. Shown in the accompanying figure is the predicted structure of triphenylmethyldiazonium cation, also known as trityldiazonium, which is a possible precursor to new polynitrogen compounds such as pentazole, a 5-membered ring system. The calculated structure shows that this cation is unstable with respect to dissociation of N2. Therefore, these calculations predict that this cation is not a viable polynitrogen precursor. (1 ref.)7
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 29, 2002
- Accession Number
- ADA410666
Entities
People
- Jerry A. Boatz
- Karl O. Christe
Organizations
- Air Force Research Laboratory