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.