Diiron ethane‐1,2‐dithiolate complexes with 1,2,3‐thiadiazole moiety: Synthesis, X‐ray crystal structures, electrochemistry and fungicidal activity

Abstract

Four diiron ethane‐1,2‐dithiolate complexes containing 1,2,3‐thiadiazole moiety have been synthesized and characterized. Esterification of the starting complex [Fe2(CO)6{μ‐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 [Fe2(CO)6{μ‐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·2H2O resulted in the formation of phosphine‐substituted analogues [Fe2(CO)5L{μ‐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 H2 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.