Reanimation: Catalytically inactive π‐allyl iron complexes are “reanimated” upon addition of N‐heterocyclic carbene ligands such as 1,3‐dimesitylimidazolin‐2‐ylidene (SIMES). A comparison of stoichiometric and catalytic allylic alkylation reactions shows the π‐allyl mechanism to be active in this catalytic system.

„Reanimieren“ lassen sich katalytisch inaktive π‐Allyl‐Fe‐Komplexe durch den Zusatz N‐heterocyclischer Carbenliganden wie SIMES (=1,3‐Dimesitylimidazolin‐2‐yliden). Der Vergleich der stöchiometrischen Alkylierung von π‐Allyl‐Fe‐Komplexen mit der durch ihre NHC‐Analoga katalysierten allylischen Substitution der entsprechenden Allylcarbonate belegt eindeutig, dass allylische Substitutionen nach dem π‐Allyl‐Mechanismus möglich sind.

Some novel complexes (1-9) of [(η 3 -allyl) Fe(CO)2(NO)] were synthesized by the reaction of tetrabutylammonium ferrate (TBAFe) with different allyl substrates like substituted allyl chlorides, allyl bromides, etc. All the synthesized complexes were characterized on the basis of infrared (IR), nuclear magnetic resonance ( 1 H-NMR and 13 C-NMR), and mass spectroscopic data. The spectroscopic data revealed that decarbonylation occurred in each case. It has also been observed that the cleavage of one CO ligand is more facile when more electron donating substituents are located at the allyl ligand. This tendency goes to an extreme in case of the 1,3-dimethylallyl Fe-complex (9).

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In this paper we report the preparation of two (h3-allyl)carbonylnitrosyltriphenylphosphine iron complexes i.e.(p-allyl)carbonylnitrosyltriphenylphosphine iron (1) and (2-methyl-p-allyl) carbonylnit rosyltriphenylphosphine iron (2). These complexes (1) and (2) were prepared by reacting (p-allyl)dicarbonylnitrosyl iron and (2-methyl-p-allyl)dicarbonylnitrosyl iron with triphenylphosphine under inert atmospheric conditions. Both the resulting complexes were sufficiently and well characterized by IR, 1H NMR, 13C NMR, ESI/MS, HRMS and single crystal XRD. Triphenylphosphine ligand was found to be strong sigma donor and replaced carbonyl ligand readily. XRD revealed that the geometry of iron in both complexes is distorted octahedral.