1,3-Diethynyl-5-(X)-benzene-Bridged [Cp*(dppe)Fe]n+ Units: Effect of Substituents on the Metal-Metal Interactions
Résumé
The new complexes [1,3-{Cp*(dppe)Fe−C≡C-}2-5-(X)-(C6H3)] (X=CH3, [m-1 b]; X=C(O)OCH3, [m-1 c]; X=C≡C-4-C6H4-C(O)OCH3, [m-1 d]; X=C≡C-4-C6H4-NO2, [m-1 e]) were prepared by reaction of the iron chloride Cp*(dppe)FeCl (4) and the proligands 3 b-e obtained by a cross coupling reaction between the suitable aryl dibromides and trimethylsylilacethylene. After purification the complexes [m-1 b–e] were isolated in yields ranging from 14 to 37 % and characterized by elemental analysis, high-resolution, ESI-mass spectra, multinuclear NMR, cyclic voltammetry, and IR spectroscopy. The complexes [m-1 b], [m-1 d], and [m-1 e] were also characterized by XRD analyses on single crystals. The doubly oxidized complexes [m-1 b–e](PF6)2 were prepared (in ca. 64–87 % yields) by treatment of a CH2Cl2 solution of the corresponding neutral complexes [m-1 b–e] with two equiv. of [(C5H5)2Fe](PF6). The mixed-valence complexes (MV) [m-1 b–e](PF6) were obtained by comproportionation between one equiv. of [m-1 b–e] and one equiv. of [m-1 b–e](PF6)2. CV, IR and NIR data led to the conclusion that the MV [m-1 b–e](PF6) complexes are weakly coupled Class II MV derivatives and the distribution of the charge between the alkynyl iron centers and the phenyl ring might be tuned by the X-substituents in a limited extend. © 2021 Wiley-VCH GmbH.
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Chimie
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Lepont et al-2021-1,3-Diethynyl-5-(X)-Benzene-Bridged [Cp(dppe)Fe]n+ Units.pdf (2.37 Mo)
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