Synthesis and (spectro)electrochemistry of mixed-valent diferrocenyl–dihydrothiopyran derivatives

摘要: Three novel diferrocenyl complexes were prepared and characterised. 2,2-Diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran (1, sulphide) was accessible by the hetero-Diels–Alder reaction of thioketone with 2,3-dimethyl-1,3-butadiene. Stepwise oxidation 1 gave respective oxides 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1-oxide (2, sulfoxide) 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1,1-dioxide (3, sulfone), respectively. The molecular structures 3 in solid state determined single crystal X-ray crystallography. sulphide to sulfone 3, plays only a minor role on overall structure two compounds. Electrochemical (cyclic voltammetry (= CV), square wave SWV)) spectroelectrochemical (in situ UV-Vis/NIR spectroscopy) studies carried out. CV SWV measurements showed that an increase sulphur atom from −2 +2 causes anodic shift ferrocenyl-based potentials about 100 mV. electrochemical 1–3 generates mixed-valent cations 1+–3+. These monooxidised species display low-energy electronic absorption bands between 1000 3000 nm assigned IVCT Inter-Valence Charge Transfer) transitions. Accordingly, 1+–3+ are classified as weakly coupled class II systems according Robin Day.