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Synthesis and characterization of tetracarbonyl(6-ferrocenyl-2.2'-bibyridine)tungsten(0) complex

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2005
Edinç, Pelin
In this study, a bidentate ligand, 6-ferrocenyl-2,2'-bipyridine, was prepared by the reaction of lithiated ferrocene with bipyridine. The ligand was identified by 1H, 13C- NMR and HMQC and UV-Vis spectroscopies. Then, bidentate molecule was reacted with pentacarbonylbis-(trimethylsilylethyne)tungsten(0). The ligand substitution reaction in CH2Cl2 yielded the new complex, tetracarbonyl(6-ferrocenyl-2,2'bipyridine)tungsten(0). The isolated and purified complex was fully characterized by elemental analysis, IR, UV-Vis, MS, 1H and 13C- NMR spectroscopies. Tetracarbonyl(6-ferrocenyl-2,2'bipyridine)chromium(0) was also formed by ligand substitution reaction of 6-ferrocenyl-2,2'-bipyridine with pentacarbonyl(THF)chromium(0) which was prepared by photolytic substitution of CO from hexacarbonyl chromium(0) in THF. However, tetracarbonyl(6-ferrocenyl-2,2'bipyridine)chromium(0) could not be isolated by column chromatography. Electrochemistry of 6-ferrocenyl-2,2'-bipyridine and tetracarbonyl(6-ferrocenyl-2,2'bipyridine)tungsten(0) was studied by cyclic voltammetry and controlled potential electrolysis combined with UV-Vis. The ligand exhibits a reversible reduction and a reversible oxidation belonging to bipyridine and ferrocene moieties, respectively. One reversible reduction, two irreversible oxidation and a reversible oxidation were observed for tetracarbonyl(6-ferrocenyl-2,2'bipyridine)tungsten(0). The reversible reduction was attributed to bipyridine whereas two irreversible oxidations were assigned to tungsten centers and reversible oxidation to iron center.