Photolysis of (Eta-5-C5h5)Fe(Co)2(Butadienyl) Complexes - Synthesis and Electrocyclic Ring-Closure of (Eta-5-C5h5)Fe(Pentadienoyl) Complexes to Hydroxyferrocenes
by Dawson, David P.; Yongskulrote, Warunee; Bramlett, J. Morris; Wright, J. B.; Durham, B.; Allison, Neil T.
A study of the synthesis and photolysis of seven (eta5-C5H5)Fe(CO)2(eta1-1,3-butadienyl) complexes is reported. Photolysis of these complexes leads to the formation of the rarely accessible class of substituted hydroxyferrocenes in very high yields. Low-temperature experiments aimed at elucidating the mechanism of this conversion indicate that loss of a terminal carbonyl from (eta5-C5H5)Fe(CO)2(eta1-1,3-butadienyl) complexes is the only photochemical reaction and that (eta5-C5H5)Fe(eta5-pentadienoyl) complexes are intermediates. Spectroscopic data for two kinetically unstable pentadienoyl intermediates are presented. Pentadienoyl ligands undergo electrocyclic ring closure followed by keto-enol tautomerization to give the hydroxycyclopentadienyl ligands. Acid catalyzes this ring-closure reaction with the rate of closure being linearly dependent on the concentration of acid. Ring strain and electronic effects also influence the rate of formation of substituted bicyclic hydroxyferrocenes.
- Journal
- Organometallics
- Volume
- 13
- Issue
- 10
- Year
- 1994
- Start Page
- 3873-3880
- URL
- https://dx.doi.org/10.1021/om00022a024
- ISBN/ISSN
- 1520-6041; 0276-7333
- DOI
- 10.1021/om00022a024