Cyclooligomerizations as Possible Routes to Cubane-Like Systems
Abstract
Octanitrocubane and 1,3,5,7-tetranitro-2,4,6,8-tetraazacubane are predicted to be high-performance energetic materials; however neither compound has as yet been synthesized. In principle, they could be prepared by the cyclooligomerizations of dinitroacetylene and nitryl cyanide, respectively. There is some encouraging chemical evidence that this may be feasible. The first steps in these processes might conceivably be cyclic dimerizations to form tetranitrocyclo-butadiene and 1,3-dinitro-2,4-diazacyclobutadiene. We have used a density functional computational procedure, B3P86/6-31G(**), to analyze these proposed initial reactions. Optimized geometries and energies were calculated for dinitroacetylene and nitryl cyanide, the two cyclic dimers, the intervening transition states, and also the desired ultimate products, the two cubanes. The activation barriers for the conversions of dinitroacetylene and nitryl cyanide to the four-membered rings were found to be 47 and 45 kcal/mole, respectively, with the overall heats of reaction being 40 and +27 kcal/mole. The heats of reaction for proceeding from the starting materials to the final cubanes were -145 and +19 kcal/mole. The corresponding free energy changes were obtained, and are also negative for the dinitroacetylene processes and positive for the nitryl cyanide. Thermodynamically, the cyclooligomerization of dinitroacetylene, whether to the dimer or to the cubane system, is predicted to be greatly favored over that of nitryl cyanide.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 08, 1999
- Accession Number
- ADA364287
Entities
People
- John J. Wiener
- Pat Lane
- Peter Politzer
Organizations
- University of New Orleans