Author(s):
Kaczor, Agnieszka 
; Almeida, Rui ; Gómez-Zavaglia, Andrea ; Cristiano, Maria de Lurdes S. ; Fausto, Rui
Date: 2008
Persistent ID: http://hdl.handle.net/10316/5024
Origin: Estudo Geral - Universidade de Coimbra
Subject(s): Methyl pseudosaccharyl ether; Molecular structure; IR spectra; Matrix isolation; DFT and ab initio calculations
Description
The computational description of saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent SO bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predictive capabilities were then evaluated by comparing the obtained results with experimentally available data, namely the newly obtained IR spectra of MBID isolated in low-temperature inert matrices. For each method, different basis sets [6-31++G(d,p), 6-31++G(3df,3pd), 6-311++G(d,p), 6-311++G(2df,2pd), 6-311++G(3df,3pd), aug-cc-pVDZ and aug-cc-pVTZ] were considered. The best overall agreement has been achieved at the B3LYP/6-311++G(3df,3pd) and B3LYP/6-31++G(3df,3pd) levels of theory, showing the adequacy of the B3LYP functional to describe the investigated properties in this type of compounds and stressing the relevance of including high-order polarization functions in the basis set. http://www.sciencedirect.com/science/article/B6TGS-4P12J8K-2/1/f46c26e1c06851bbcd7c3f15399af757
