SYNTHESIS AND OXIDATION OF IRON(II) FERROCENYLACETYLIDE DIPHOSPHINE COMPLEXES - A NOVEL TYPE OF MIXED-VALENCE COMPLEX

Some Fe(II) ferrocenylacetylide complexes, [(Cp or Cp)(PP)FeC drop CF c], were prepared by the photolysis of the corresponding carbonyl comp lexes [(Cp or Cp)(CO)(2)FeC drop CFc] in the presence of diphosphines (PP = dppe, dppm, dmpe). The cyclic voltammograms showed two quasi-re versible waves at -0.47 to -0.84 and +0.08 to +0.12 V. The one-electro n-oxidized species were isolated as relatively stable solids from the reaction of the neutral Fe(II) complexes with DDQ or FcHPF(6). The oxi dized complexes exhibited an intervalence transfer band at 1295-1595 n m, and the interaction parameters were calculated from the position (a lpha(2) = (0.98-2.44) x 10(-2)). This suggests that these are highly e lectron delocalized mixed-valence complexes. The IR spectra (nu(cc) = 1956-1976 cm(-1)), the ESR spectra (appearance of one broad signal), a nd the Mossbauer spectra (QS = 2.00-2.26 mm s(-1)) support the above s uggestion. The structure of [Cp(dppe)FeC drop CFC] was determined by s ingle-crystal X-ray diffraction.