| Abstract
| - A series of 3,4-disubstituted (hex-3-ene-1,5-diyne-1,6-diyl)diron complexes with FeCp*(dppe) (Fe)end caps, Fe−C⋮CC(R)C(R)C⋮C−Fe (R = H, C⋮C−SiMe3, C⋮C−H, C6H5, p-C6H4CF3), and therelated (octa-3,5-diene-1,7-diyne-1,8-diyl)diron complex, Fe−C⋮C−C(H)C(H)C(H)C(H)C⋮C−Fe,has been prepared, and their performance as molecular wires has been evaluated. The enyne complexeshave been synthesized via vinylidene intermediates, [FeCC(H)C(R)C(R)C(H)CFe]2+, derivedfrom the corresponding terminal alkynes or the Me3Si-protected precursors (XC⋮CCC(R)C(R)C⋮C−X; X = H, SiMe3), and the products have been characterized spectroscopically and crystallographically.The performance of the obtained dinuclear enyne complexes as molecular wires has been evaluated onthe basis of the comproportionation constants (KC) obtained by electrochemical measurements and theVab values obtained from the spectral parameters of the intervalence charge transfer bands of the isolatedmonocationic radical species appearing in the near-IR region. As a result, the C6-enediyne complexesturn out to be excellent molecular wires, with KC values larger than 108 as well as Vab values larger than0.35, belonging to class III compounds according to the Robin and Day classification and being comparableto the related polyynediyl complexes as well. It is notable that, in the enyne system, the performance canbe readily tuned by introduction of appropriate substituents onto the olefinic part. Thus, diiron complexescontaining an enyne spacer can be regarded as tunable molecular wires.
- A series of 3,4-disubstituted (hex-3-ene-1,5-diyne-1,6-diyl)diron complexes with FeCp*(dppe) end caps, Fe−C⋮C−C(R)C(R)C⋮C−Fe (R = H, C⋮C−SiMe3, C⋮C−H, C6H5, p-C6H4CF3; Fe = FeCp*(dppe)), and the related C8 complex, Fe−C⋮C−C(H)C(H)C(H)C(H)C⋮C−Fe, have been prepared, and their performance as molecular wires is evaluated on the basis of the KC and Vab values. It is concluded that the diiron complexes consisting of an enyne spacer belong to class III and their performance can be tuned by introduction of appropriate substituents onto the olefinic part.
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