77944-67-3Relevant academic research and scientific papers
Stereochemistry and mechanisms of cleavage of compounds of the type (η5-C5H5)Fe(CO)2(alkyl) with copper(II) reagents and halogens. Possible roles of solvent cage processes in organometallic cleavage reactions
Rogers, William N.,Page, John A.,Baird, Michael C.
, p. 3521 - 3528 (2008/10/08)
Cleavage reactions by a variety of copper(II) reagents of the compounds FpR (Fp = (η5-C5H5)Fe(CO)2; R = Me, Et, n-Bu, PhCH2CH2, threo-PhCHDCHD, PhCH213CH2, Me3CCH2CH2, PhCH2, (R)-(-)-PhCHD, Me3CCH2, s-Bu) and (η5-C5H5)FeCOPPh3R (R = PhCH2, (R)-(-)-PhCHD) are studied and compared with similar electrochemical and halogen cleavage reactions. In general, reaction of FpR with a copper(II) halide, CuX2, yields [FpR+][CuX2-] via a one-electron-transfer process. When R = Me or PhCH2, the ion pair breaks down within the solvent cage via nucleophilic attack by halide ion on the α-carbon atom of R, the products being RX (inversion of configuration) and the iron radical Fp·. The latter then abstracts halogen from copper(II) halide or halogenated solvent. When R = n-Bu on Me3CCH2CH2, the components of [FpR+][CuX2-] diffuse from the solvent cage and the cation undergoes homolysis of the iron-carbon bonds to give Fp+ and R·; the latter abstracts halogen from copper(II) halide or halogenated compound. The major difference between the two series appears to be the proclivity of R to undergo SN2-type processes, i.e., PhCH2, Me > n-Bu, Me3CCH2CH2, although the benzyl system will also undergo homolysis to yield benzyl radicals when good nucleophiles are absent. Reactions of FpCH2CH2Ph proceed by a third route, dissociation of phenonium ions. It is also shown that halogen cleavage reactions of the compounds FpR in nonprotic solvents probably proceed via a two-electron-transfer process. The presumed intermediates, [FpRX+][X-], appear to undergo more facile nucleophilic attack by halide ion on the α-carbon atom of R than do the species FpR+, yielding RX (inversion of configuration) and FpX.
