3.    Metal ion mediated facile intramolecular organic transformations :

The aromatic thiolation ( C6H5 C6H4 S ) and hydroxylation ( C6H5 C6H4 O) reactionsare known to be important chemical processes. Although the conversions of C6H5 C6H4-S and C6H5 C6H4-O are conventionally multistep processes, the metal ion prompted activations of the C H and C Cl bonds of the aromatic ring have led to the spontaneous one-pot syntheses of coordinated aromatic thiols and phenols in the presence of selective thiolating and hydroxylating agents, respectively. The mechanistic studies have revealed that C Cl bond activation process follows the nucleophilic substitution pathway whereas the C H bond activation process proceeds via the formation of intermediate cyclometallated state followed by insertion of "S" or "O" into the reactive M C bond. Moreover, metal ion mediated facile formations of amidine and iminoesters and unusual reductive cleavage of tetrazine ring have also been addressed.

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