18712-14-6Relevant articles and documents
Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (methyl pseudosaccharyl ether)
Kaczor, Agnieszka,Almeida, Rui,Gómez-Zavaglia, Andrea,Cristiano, Maria de Lurdes S.,Fausto, Rui
, p. 77 - 85 (2008)
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 S{double bond, long}O 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. The chosen level of theory [B3LYP/6-311++G(3df,3pd)] was applied to analyze the vibrational spectra and the geometry of the title molecule. In agreement with the experiment, the C{single bond}O{single bond}C linkage in MBID is predicted by these calculations to exhibit considerably short (1.320 ?) and long (1.442 ?) (N{double bond, long})C{single bond}O and (H3)C{single bond}O bonds, respectively, and a hybridization of the central oxygen atom close to sp2 (the C{single bond}O{single bond}C angle is predicted to be ca. 117°). This C{single bond}O{single bond}C bonding pattern fits the well-known high reactivity of MBID upon thermal rearrangement, which has been shown to result in easy selective [1,3′]-isomerization of the compound.
