Ab initio conformational study of the P6 potential surface: Evidence for a low-lying one-electron-bonded isomer

✍ Scribed by Philippe C. Hiberty; François Volatron

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 419 KB
• Volume: 18
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.20324

✦ Synopsis

Abstract

The low‐lying isomers of the P~6~ species are investigated at various levels of calculations, ranging from MP2/6‐31G(d) to CCSD(T) in triple‐zeta basis set involving polarization functions up to f. In addition to the five possible normal‐valent isomers, which obey the octet rules, several other conformations are found to be stationary points on the potential energy surface. Among the five normal‐valent isomers, the benzvalene structure is found to be the most stable one, in agreement with former studies. The benzene‐like D~6h~ planar hexagon is the least stable one, lying 32.3 kcal/mol over benzvalene, and spontaneously distorts to a less symmetrical, nonplanar six‐membered ring. Above the benzvalene structure, and lying, respectively, 5.8 and 15.8 kcal/mol higher, the two lowest lying isomers are the prismane and the chair‐like forms. This latter conformation, which does not obey the octet rule, exhibits two one‐electron PP hemibonds and can be considered as a generic model for a new category of heterobenzene analogs, among which is the recently discovered dimer of diphosphirenyl radical. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:129–134, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20324