Abstract A series of germinal-diethynylethene (gem-DEE) bridged diferrocenyl compounds, including 1,1-[bis(ferrocenylethynyl)methylene]cyclohexane (1), 1,1-[bis(ferrocenylethynyl)methylene]tetrahydro-2H-pyran (2), and 1,1-[bis(ferrocenylethynyl)methylene]tetrahydro-2H-thiopyran (3) were synthesized and characterized. The Fe⋯Fe distance between the two ferrocenyl termini reaches… Click to show full abstract
Abstract A series of germinal-diethynylethene (gem-DEE) bridged diferrocenyl compounds, including 1,1-[bis(ferrocenylethynyl)methylene]cyclohexane (1), 1,1-[bis(ferrocenylethynyl)methylene]tetrahydro-2H-pyran (2), and 1,1-[bis(ferrocenylethynyl)methylene]tetrahydro-2H-thiopyran (3) were synthesized and characterized. The Fe⋯Fe distance between the two ferrocenyl termini reaches up to ∼9 A for compounds 2 and 3. The electrochemical measurements demonstrate moderate electronic coupling between the gem-DEE-bridged ferrocenyl (Fc) termini in this cross-conjugated system. UV–vis–NIR spectroscopy studies suggest that the monocation species of these compounds belong to class II mixed-valence systems in Robin–Day classification. DFT calculations further reveal electronic structures of these cross-conjugated diferrocenyl compounds.
               
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