A Theoretical Study on ~(13)C-NMR of 2-Butyl-tetrahydrothiophene-1-oxide

The 13C-NMR chemical shifts of cis- and trans-2-nutyl-tetrahydrothiophene-1-oxide (BTHTO) have been calculated with RHF and B3LYP methods at the 6-31G**, 6-31+G** and 6-31++G** levels by using ab initio GIAO method. The calculated 13C chemical shifts of BTHTO are in good agreement with the experimental data. Chemical shifts calculated by the B3LYP/6-31+G**//RHF/6-31G* method is preferable. The 13C-NMR difference between cis- and trans-BTHTO has been reasonably explained by the 2p electronic population of C atoms, geometry and electrostatic potential of the molecules. Geometries of cis- and trans-THTO optimized at the RHF/6-31G* and B3LYP/6-31G* levels indicated that the tetrahydrothiophene cycle is of half-chair conformation.