Synthesis and structural characterization of new multiferrocenyl diyne ligands and their cobalt carbonyl complexes

New multiferrocenyl diyne ligands FcC(CH3)2Fc′–C≡C–C≡C–Fc [L 1 ; Fc = C5H5FeC5H4; Fc′ = C5H5Fe(1,3-disubstituted)C5H3], FcC(CH3)2Fc′–C≡C–C≡C–Fc′C(CH3)2Fc (L 2 ) and their complexes [FcC(CH3)2Fc′–C≡C–C≡C–Fc][Co2(CO)6] n [n = 1, (1); n = 2, (2)], [FcC(CH3)2Fc′–C≡C–C≡C–Fc′C(CH3)2Fc][Co2(CO)6] n [n = 1, (3); n = 2, (4)] have been synthesized by the coupling reaction of terminal ferrocenylacetylene and the reaction of ligands L1 and L2 with Co2(CO)8. The composition and molecular structure of the ligands L1 , L2 and their cobalt complexes were characterized by element analysis, IR, 1H(13C)NMR and MS. The electrochemical properties of compounds L1 , L2 , 1, 2, 3, 4 were studied by cyclic voltammetry(CV). The results of the electrochemical research reveal that all three ferrocenyl groups in L1 become redox active centers, but there are only two (not four) ferrocenyl redox active centers in L2 .