Complex Syntheses Using Electronic Charge and Softness of Organothallium Crown-ether Complexes

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The reaction of [Phenylthallium(III)(18-crown-6)] diperchlorate,[PhTl^<III>(18-crown-6)](ClO_4)_2 (1 a) with phenol gives [phenyl(4'-hydroxyphenyl)tnallium(III)(18-crown-6)]diperchlorate (2). The complex 1 a reacts also with alkylphenols, methoxyphenols, catechol, resorcinol, and pyrogallol to give thallated product exclusively at the para position of the electron-donating group(OH or OCH3) without suffering from reduction of thallium(III). No reaction takes place with 4-methylphenol, benzene, toluene, Electrophilic thallation of diphenylamine, diphenylmethylamine and triphenylamine with 1 a gives compounds of the type [PhArTl^<III>(18-crown-6)](ClO_4) (Ar=4'-phenylamino)phenyl, 4'-(methylphenylamino)phenyl, and 4'-(diphenylamino)phenyl, respectively). Similar reaction of five-membered heterocycls, such as pyrrole, furan and thiophene and their derivatives, was observed at mild condition. On the other hand the reaction of 1 a with imidazole resulted in coordination of imidazole nitrogen to the thallium ion without substitution at the ring.Reactions of 1 a with Me_3SiR(R=PhCH_2, Et, Ph, CH=CH_2, SiMe_3 OSiMe_3) proceeded at 60ﾟC to provide exclusively [phenylmethylthallium(III)(18-crown-6)]perchlorate in good yield to excellent yield. Cleavage of the Me-Si bond in tetramethylsilane using 1 a also occurred at room temperature.