ON THE CAPABILITY OF SULFUR FOR Pπ-Pπ-CONJUGATION IN ISOTHIURONIUM SALTS AND RELATED SYSTEMS

Abstract The higher elements such as sulfur are often believed to have a low capability for participation in pπ-pπ bonding though thiophene is the most “aromatic” compound of the series X = NH, 0, S. In a recent review on sulfur-containing cations, Marino (1) wrote for isothiuronium salts “Clearly, the positive charge is distributed over several atoms besides sulfur, which is perhaps the least cationic of the heteroatoms”.