Unusual Two-Bond 13C,13C Coupling Constants in Sulphones

Article abstract of DOI:10.1002/mrc.1260261213

A measurable coupling between carbon atoms through the SO2 group is observed in a series of structurally diverse sulphones.In open-chain (single coupling path) sulphones this 2J coupling ranges from 5.5 to 27.2 Hz, while in cyclic (multiple coupling path) sulphones values ranging from 4.3 to 21.6 Hz are observed.Sulphides and sulphoxides do not exhibit a corresponding coupling of comparable magnitude.A positive sign for this coupling is derived from the data of cyclic sulphones.Whereas substituents and branching at the coupling termini exert minor influences on the coupling, the most important factor determining the magnitude of the 2J(CSC) coupling is the hybridization of the coupling carbon atoms.A linear relationship between the 2J value and the s character product of the C-S bond forming C orbitals is established.KEY WORDS Sulphones 13C NMR Geminal 13C,13C coupling