74171-11-2Relevant articles and documents
Preparation of homo- and heterobimetallic μ-η2-(C,C)-ketene complexes, FpCH2COMLn, and transformation of the bridging ketene ligand into various C2 functional groups
Akita, Munetaka,Kondoh, Atsuo,Kawahara, Takashi,Takagi, Takenobu,Moro-oka, Yoshihiko
, p. 366 - 374 (2008/10/08)
Eight examples of homo- and heterobimetallic μ-ketene complexes, FpCH2COMLn [3-7: Fp = (η5-C5H5)Fe(CO)2; M = Fe, Mo, Ni, Mn, Co; L = Cp, CO, PR3], are prepared by acylation of an iron-substituted acetyl chloride with various transition-metal anions. IR studies reveal the significant contribution of a π-complex Fp+[CH2=C(O-)Fp] (10) in addition to an oxycarbene structure FpCH2C(O-)=Fp+ (11) which is well-established for mononuclear acyl complexes. As a typical example, FpCH2COFp (3a) is subjected to chemical transformations relevant to catalytic CO hydrogenation. While 3a is not susceptible to carbonylation to lead to a μ-malonyl complex, decarbonylation results in quantitative liberation of ketene molecule or ligand substitution instead of formation of a μ-methylene complex. Reduction of 3a by LiAlH4 affords C3 products as major components. Reaction of 3a with electrophiles takes place at the acyl oxygen atom to give cationic binuclear oxycarbene complexes FpCH2C(OR)=Fp+TfO- (TfO = CF3SO3) (18-20) which exhibit bimodal reactivities toward both nucleophiles and electrophiles. Hard nucleophiles attack the most electrophilic carbene center, soft nucleophiles attack the alkyl side Fp group, and electrophilic reaction takes place at the methylene terminus.
