The reaction of 2 equiv of CpFe(CO)2I and 1,1′-dilithioferrocene in the presence of 2 equiv of PPh3 is an intermolecular version of the reaction of CpFe(CO)2I and (η5-C5H4Li)Fe (C5H4PPh2). In the three-component procedure, the PPh3 substitution for iodide on CpFe(CO)2I is much faster than the nucleophilic Fc-addition at the Fe-center or at a CO ligand of CpFe(CO)2I. This one-pot reaction proceeds through [CpFe(CO)2PPh3+] and yields CpFe(CO)(PPh3)- [μ,C:η5-C(O)C5H4 ]Fe[μ,η5:η4-5-exo- (1′-C5H4)C5H5]Fe (CO)2(PPh3) (4) in 50% yield, with the 1,1′-dilithioferrocene participating twice in the nucleophilic Fc-additions: at the Cp-ring and at a CO ligand of [CpFe(CO)2PPh3+]. Complex 4 is a ferrocenediyl-bridged tri-Fe complex with three different Fe-centers: a metallocene Fe(II), a square-pyramidal pentacoordinate Fe(O), and a half-sandwich acyl-Fe(II). It has been found that, in the second Fc-additions, the pathway from (η5-C5H4Li)Fe[μ,η5: C-C5H4C(O)]FeCp(CO)(PPh3) (9) to 4 proceeds normally, but the pathway from 9 to Fe[(μ,η5: C-C5H4)C(O)FeCp(CO)(PPh3)]2 (5) has been turned off. The preference of Fc-addition of 9 onto the Cp-ring of [CpFe(CO)2PPh3+] could be reasoned by a localization of the Li+ cation in 9.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry