Reactions of μ(α,ω)-alkanediyl complexes of iron(II) and tungsten(II) with tertiary phosphines and halogens; a mechanistic study

Article abstract of DOI:10.1016/0022-328X(89)87122-0

Reactions of the μ(α,ω)alkanediyl complexes <(Cp)(CO)2Fe(CH2)nFe(CO)2(Cp)> with neutral donor ligands initially give the monosubstituted monoacyl complexes <(Cp)L(CO)FeC(O)(CH2)nFe(CO)2(Cp)>, which then react further to give the disubstituted diacyl complexes <(Cp)L(CO)FeC(O)(CH2)nC(O)Fe(CO)L(Cp)> (where Cp=η⁵-C5H5; n=3-7 and L=PPh3, PPh2Me or PMe3).Similar reactions of <(Cp)(CO)3W(CH2)nW(CO)3(Cp)> with the ligands L give the disubstituted diacyl complexes <(Cp)L(CO)2WC(O)(CH2)nC(O)W(CO)2L(Cp)>, although these latter reactions are considerably slower.In contrast to the reactions of the diiron compounds, the reactions of the dinuclear di-tungsten compounds also give the mono- and di-substituted alkanediyl compounds <(Cp)L(CO)2W(CH2)nW(CO)3(Cp)> and <(Cp)L(CO)2W(CH2)nW(CO)2L(Cp)>.The reactions of the alkanediyl compounds of iron with halogens causes cleavage of both iron-carbon bonds and yield and X(CH2)nX.The mechanisms of these reactions are discussed.