Solution Structure of Some λ3 Iodanes:  An 17O NMR and DFT Study

• Published in: Journal of organic chemistry Vol. 72; no. 11; pp. 4163 - 4168
• Main Authors: Mocci, Francesca, Uccheddu, Gianluca, Frongia, Angelo, Cerioni, Giovanni
• Format: Journal Article
• Language: English
• Published: American Chemical Society 25.05.2007
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo070111h

The structure of a series of I−O bonded bis(acyloxy)iodoarenes and benzoiodoxolones in chloroform solution has been investigated by 17O NMR spectroscopy and by density functional theory (DFT) calculations, employing the PBE0 functional together with the LANL2DZ basis set extended with polarization (d) and diffuse (p) functions. This combined approach allowed us to ascertain that, although these classes of λ3 iodanes maintain in chloroform solution their solid state “T-shaped” structure, a degenerate [1,3] sigmatropic shift of iodine between the two oxygens of the acyloxy groups occurs in solution. The energy barrier involved in this process differs in the two classes, thus causing significant differences in the 17O NMR spectra, at room temperature, of the two classes of compounds.