Studies on the Active Molecules Prepared by Accumulation and Amplification of the Transannular Interaction between Chalcogen Atoms

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In this studies, it was described the preparation of the dications having 2-center-2-electron [2c-2e] system and highcoordinated dications having 3-center-4-electron [3c-4e] bonds using organic compounds bearing multiple-chalcogen atoms arranged in space. The dications of [2c-2e] substituted by alkyl and benzyl groups at the chalcogen atoms were found to be quite reactive, and their formation was either undetected or detected only by low temperature ^1H-and ^<13>C-nmr spectroscopy. These dications once formed undergo facile dealkylation to afford N-alkyl acetamides which are trapped by CH_3CN used as a solvent together with thia-sulfonium salts in high yields. The mechanism for this dealkylation is rationally explained to proceed via an S_Nl-type substitution mechanism. On the other hand, the photolysis of the monooxides, mono-N-tosylsulfilimines and mono-S-ylides of naphtho [1,8-de] -1,3-dithiin provided the corresponding ketones, N-imines and olefins quantitatively. The photolysis re … More actions may proceed via the activation of the S-S interaction of these compounds. As to the highcoordinated [3c-4e] dication species, 1-phenyl 2,6-dimethylthiomethylphenyl tellurides were converted to the telluranes on oxidation. Similarly, 1,11-methanoseleno- [or-thio] diselenocin (or dithiocin) afforded the corresponding selenurane (or sulfurane) compounds on treatment of the diselenocin (or dithiocin) with one electron oxidant such as NOBF_4. These [3c-4e] hypervalent dications can be converted readily to the starting tris-selenides (or sulfides) by reducing the dications. In these oxidation-reduction reactions of the trisselenides (or sulfides), these compounds show molecular hysteresis during oxidation-reduction. The dications were stable enough to be isolated and their structures were determined by X-ray crystallographic analysis. The ab initio MO-calculation of these compounds reveal the charge-distribution among the atoms in the hypervalent molecules which was discussed with their reactivities. Less