Calculated structures and relative stabilities of furoxan, some 1,2-dinitrosoethylenes and other isomers

✍ Scribed by Jorge M. Seminario; Monica C. Concha; Peter Politzer

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 396 KB
• Volume: 13
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540130209

✦ Synopsis

The structures and relative stabilities of furoxan and some of its isomers, e.g., the 1,Z-dinitrosoethylenes, have been determined by means of ab initio Hartree-Fock and Mgller-Plesset calculations. Geometries were optimized at the HF/3-21G, HF/6-31G* and MP2/6-31G* levels, and subsequently used for computing MP2/6-31G*, MP3/631G*, and MP4/631G* energies. The results are markedly affected by the inclusion of electronic Correlation, which renders three of the isomers unstable. It also emphasizes the importance of a zwitterionic contribution to the structure of furoxan, which promotes ring-opening through a cis 1,2-dinitrosoethylene intermediate/transition state that has an MP4/631G*//MPZ/6-31G8 energy that is 31.6 kcal/mol above furoxan.

A number of structural isomeric forms can be drawn for furoxan, V. Some of these are shown below (VI-XII); VI-IX are conformational isomers of 1,2-dini- trosoethylene. The cis-l,2-dinitrosoetfiylenes VI and VII are of particular interest, since it is believed that *Author to whom all correspondence should be addressed.