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Synthesis and reactivity of a new type of crown ether thiosemicarbazone
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1  University of Santiago de Compostela, Department of Inorganic Chemistry


Palladacycles are very versatile compounds and they are known for a good number of ligands. Their main applications are as catalysts, sensors or as antitumor agents. In the particular case of the thiosemicarbazone ligands, these react with palladium salts to give very robust cyclometallated compounds, which present great air and thermal stability; the ligands themselves show a high biological activity. Moreover, when the corresponding thiosemicarbazone is functionalized with a crown-ether moiety, the resulting palladacycle behaves as a new type of sensor.

Once palladated the thiosemicarbazone ligand behaves as tridentate, thus occupying all but one of the coordination positions in the square planar environment of the palladium atom. If the ligand is forced to react in the thione fashion with respect to the sulfur atom, the resulting palladacycle is a mononuclear species with the fourth coordination position readily accessible for further modifications.

In this communication we present the synthesis of [3,4-(C8H16O5) C6H3C(H)=NN(Me)C(=S)NH2] (1) and its reactivity towards Li2PdCl4 to obtain the mononuclear cyclometallated compound [Pd{3,4-(C8H16O5)C6H3C(H)=NN(Me)C(=S)NH2}(Cl)] (1Pd). The characterization of both compounds was carried out using IR and 1H NMR spectroscopy.

Keywords: Crown-ethers, palladacycle, thiosemicarbazone