✦ LIBER ✦
Proton n.m.r. spectra of furo[3,2-c] and furo[2,3-c]thiapyrylium cations, compared with their thieno homologues. Correlations between chemical shifts and charge densities from CNDO/2 and PPP calculations
✍ Scribed by Flora Catti Boccuzzi
- Publisher
- John Wiley and Sons
- Year
- 1976
- Tongue
- English
- Weight
- 256 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Significant variations of thiapyrylium chemical shifts, by comparison with their thienohomologues, are shown by ^1^H n.m.r. spectra of furo[3,2‐c]thiapyrylium and furo[2,3‐c]thiapyrylium perchlorates. The observed changes can be ascribed to a different distribution of the electron charge (mainly caused by participation of the 3d orbitals of sulphur in the thienohomologues) and to a different contribution of the ring current; this is shown by MO calculations performed by the CNDO/2 and the coupled Hartree–Fock methods, respectively.