12177-27-4Relevant academic research and scientific papers
Cyclopentadienyldicarbonyliron halides as electrophiles: Reactions of (η5-C5H5)Fe(CO)2X with RLi in the presence of PPh3 to produce (η4-exo-RC5H5)Fe(CO)2(PPh 3) and preparation of [(η5-C5H5)Fe(CO)C(O)Me](μ,η ...
Liu, Ling-Kang,Luh, Lung-Shiang
, p. 2816 - 2824 (2008/10/08)
Full title: Cyclopentadienyldicarbonyliron halides as electrophiles: Reactions of (η5-C5H5)Fe(CO)2X with RLi in the presence of PPh3 to produce (η4-exo-RC5H5)Fe(CO)2(PPh 3) and preparation of [(η5-C5H5)Fe(CO)C(O)Me](μ,η 1,η1-dppf)[(η4-exo-MeC 5H5)Fe(CO)2]. The reaction of (η5-C5H5)Fe(CO)2X (X = Cl, Br, I) with RLi (R = Me, n-Bu, s-Bu, Ph) in the presence of PPh3 at low temperature changes the η5-C5H5 bonding mode in (η5-C5H5)Fe(CO)2X to an η4-RC5H5 bonding mode in (η4-RC5H5)Fe(CO)2(PPh 3). The X-ray results of (η4-BuC5H5)-Fe(CO)2(PPh 3) reveal an exo-Bu group at the cyclopentadiene ring. The nucleophilic addition of R- is therefore a direct one, without the Fe mediation. Generated in situ, [(η5-C5H5)Fe(CO)2]2 is believed to be the catalyst in the conversion of (η5-C5H5)Fe(CO)2X and PPh3 to the cationic intermediate [(η5-C5H5)Fe(CO)2(PPh 3)]+ which is much more electrophilic toward R- to produce (η4-exo-RC5H5)Fe(CO)2(PPh 3). The conformation of (η4-exo-RC5H5)Fe(CO)2(PPh 3) may be described as a pseudo-square-pyramid with one of the CO ligands at the apical position. Refluxing 1:2 (η5-C5H5)Fe(CO)2Me, and dppf gives (η5-C5H5)Fe(CO) (η1-dppf)C(O)Me which, upon treatment of MeLi at low temperature, yields [(η5-C5H5)Fe(CO)C(O)Me] (μ,η1,η1-dppf)[(η4-exo-MeC 5H5)-Fe(CO)2], a complex with a dppf linking two iosmeric, methylated [(C5H5)Fe(CO)2]units, one end in the form of (η5-C5H5)Fe(CO)C(O)Me and the other end in the form of (η4-exo-MeC5H5)-Fe(CO)2.
