Chemistry of N-F Containing HEDM Materials and on Lewis Acidity of LiF
Abstract
The recent isolation of the N5+ cation is one of the most amazing discoveries of modern chemistry. This statement is justified by the fact that this is the first all nitrogen homoleptic species to be isolated in more than a century, and only the third known species of this kind besides atmospheric nitrogen (N2) and the azide ion (N3(-)). The N5(+)AsF6(-) salt is only marginally stable at room temperature. In order to prepare other more stable N5(+) salts for application as high energy density material, it was necessary to prepare the corresponding precursors in an efficient manner and in large quantities. The choice of common natural graphite flake as opposed to HOPG for the graphite. AsF5 intercalate formation reduces not only the cost drastically, but also the intercalation time from several weeks to two days. This intercalate is then used to reduce N2F4 to N2F2. Using the graphite flake intercalate, this reduction reaction was accomplished in several hours instead of weeks with minimal formation of by-products. Another major discovery made during this study is the catalytic conversion of trans-N2F2 to its cis-isomer when SbF5 is used as the Lewis acid. This reduces the number of steps required for the preparation of the precursor, N2F(+)SbF6(-), and avoids the need for an extra step involving the corresponding expensive AsF6(-) salt. Also, discovered during the isomerization studies is a novel synthetic route to prepare NF4(+) salts at relatively low temperature and pressure that does not require elemental fluorine and NF3. A structural analysis of the N2F(+) cation was also carried out by the crystal structure determination of N2F(+)SbF6(-) and N2F(+)Sb2F11(-).
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 03, 2000
- Accession Number
- ADA408393
Entities
People
- Ashwani Vij
- Jeffery A. Sheehy
- Karl O. Christe
- Vandana Vij
- William W. Wilson
Organizations
- Air Force Research Laboratory