Preparation and properties of methyliron complexes with tertiary phosphine ligands and their decomposition pathways through the formation of carbenoid intermediates

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Reaction of Fe(acac) 3, AlMe 2(OEt) and 1,2-bis(diphenylphosphino)ethane (dpe) gives a new dimethyliron complex, Fe(CH 3) 2(dpe) 2 (I). Complex I is unstable in solution and gives a methyliron complex containing an ortho-metallated ring, Fe(CH 3)(dpe) {Ph 2PCH 2CH 2PPh( o-C 6H 4)} (II) with liberation of methane. On thermal decomposition and treatment with CH 2Cl 2 compound I liberates ethylene, the formation of which suggests the intermediacy of carbenoid complexes. Reactions of I with H 2 or D 2, carbon dioxide and phenylacetylene yield FeH 2(dpe) 2 · C 6H 6 (IV) or FeD 2(dpe) 2 · C 6H 6 (VI), Fe(OOCCH 3)(CO 2) m (py) n (VII) and FeH(CCPh)(dpe) 2 (VIII), respectively. I initiates the polymerization of acrylonitrile. Employment of PPhMe 2 instead of dpe in the reaction of Fe(acac) 3 and AlMe 2(OEt) gave a new methylbis(acetylacetonato)iron(III) complex, Fe(CH 3)(acac) 2(PPhMe 2) (V). I and V react with carbon monoxide to yield acetone.