Diiron Ethane‐1,2‐dithiolate Complexes with 1,2,3‐thiadiazole Moiety: Synthesis, X‐ray Crystal Structures, Electrochemistry and Fungicidal Activity

Four diiron ethane-1,2-dithiolate complexes containing 1,2,3-thiadiazole moiety have been synthesized and characterized. Esterification of the starting complex [Fe-2(CO)(6){mu-SCH2CH(CH2OH)S}] (1) with 4-methyl-1,2,3-thiadiazole-5-carboxylic acid in the presence of 4-dimethylaminopyridine and N,N '-dicyclohexylcarbodiimide yielded the corresponding ester [Fe-2(CO)(6){mu-SCH2CHCH2O2C(4-C2N2SCH3)S}] (2) in good yield. Further treatment of complex 2 with a phosphine ligand triphenylphosphine, tris(2-methoxyphenyl)phosphine, or tri(p-tolyl)phosphine and the decarbonylation reagent Me3NO center dot 2H(2)O resulted in the formation of phosphine-substituted analogues [Fe-2(CO)(5)L{mu-SCH2CHCH2O2C(4-C2N2SCH3)S}] [L = PPh3, 3; P(2-C6H4OCH3)(3), 4; P(4-C6H4CH3)(3), 5] in 60 - 80% yields. The new complexes 2-5 were characterized by elemental analysis, IR and NMR spectroscopy and further confirmed by X-ray diffraction analysis. The electrochemical properties were studied by cyclic voltammetry, showing that these complexes can catalyse the reduction of protons to H-2 in the presence of HOAc. In addition, the fungicidal activity studies revealed that the hydroxy group possibly play a significant role in the biological activity.