Ylide character and stability of heterocyclic benzenes

✍ Scribed by M. Z. Kassaee; E. Vessally; H. Pirelahi; S. Arshadi

• Book ID: 102231962
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 232 KB
• Volume: 19
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.20443

✦ Synopsis

Abstract

Optimizations are carried out on heterocyclic benzenes including oxabenzene (1~O~), thiabenzene (1~S~), selenabenzene (1~Se~), tellurabenzene (1~Te~), 1,1‐dihydropyridinium (2~N~), 1,1‐dihydrophosphinium (2~P~), 1,1‐dihydroarsinium (2~As~), and 1,1‐dihydrostybinium (2~Sb~), using HF and DFT methods with 6‐311++G* basis sets. These partly aromatic compounds have 6π‐electrons showing ylide character. Nonplanar boat conformers appear as global minima for 1~X~. In contrast, planar conformers are the most stable in 2~X~ series. The inversion barrier energy of heteroatom in 1~O~ appears the least in 1~X~ structures. Ylide character increases in series 1~X~ and 2~X~ with the orders of 1~Te~ > 1~O~ > 1~Se~ > 1~S~ and 2~As~ > 2~N~ > 2~Sb~ > 2~P~, respectively. Homodesmic studies show stability order for series 1~X~ to be 1~S~ > 1~Se~ > 1~Te~ > 1~O~, whereas the order of stability for series 2~X~ is 2~As~ > 2~P~ > 2~Sb~ > 2~N~. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:412–417, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20443