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Synthesis and Oxidation of Iron(II) Ferrocenylacetylide Diphosphine Complexes. A Novel Type of Mixed-Valence Complex

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posted on 1996-01-23, 00:00 authored by Masaru Sato, Yukiko Hayashi, Shigekazu Kumakura, Natsuko Shimizu, Motomi Katada, Satoshi Kawata
Some Fe(II) ferrocenylacetylide complexes, [(Cp or Cp*)(PP)FeC⋮CFc], were prepared by the photolysis of the corresponding carbonyl complexes [(Cp or Cp*)(CO)2FeC⋮CFc] in the presence of diphosphines (PP = dppe, dppm, dmpe). The cyclic voltammograms showed two quasi-reversible waves at −0.47 to −0.84 and +0.08 to +0.12 V. The one-electron-oxidized species were isolated as relatively stable solids from the reaction of the neutral Fe(II) complexes with DDQ or FcHPF6. The oxidized complexes exhibited an intervalence transfer band at 1295−1595 nm, and the interaction parameters were calculated from the position (α2 = (0.98−2.44) × 10-2). This suggests that these are highly electron delocalized mixed-valence complexes. The IR spectra (νCC = 1956−1976 cm-1), the ESR spectra (appearance of one broad signal), and the Mössbauer spectra (QS = 2.00−2.26 mm s-1) support the above suggestion. The structure of [Cp(dppe)FeC⋮CFC] was determined by single-crystal X-ray diffraction.

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