Reactions of iron atoms with unsaturated hydrocarbons

Bis-N-Heterocyclic Carbene (NHC) Stabilized η6-Arene Iron(0) Complexes: Synthesis, Structure, Reactivity, and Catalytic Activity

“…Complexes 3 and 4 are remarkable since they are (other than 4- d 6 ) the first examples of Fe(0) arene complexes supported exclusively by NHC ligands. This is even more surprising, when one considers the fact that complexes of the type [Fe(η 6 -arene)(PR 3 ) 2 ] (R = halogen, alkyl, or aryl substituent) have existed since 1972 . Despite their early entry in the literature, these complexes have escaped characterization by structural methods, probably as a result of their extreme reactivity, or the fact that they are liquids at ambient temperature .…”

“…Moreover access to these complexes typically require complicated metal vapor synthetic techniques, making their access somewhat difficult . The related and somewhat more robust arene complexes by Girolami and co-workers bearing a chelating phosphane ligand, [P 2 Fe(η 6 -arene)] (P 2 = chelating bidentate phosphane ligand), have been known for more than 15 years but have also escaped structural characterization, while the related complex [P 2 Fe(η 6 -napthalene)], reported by Komiya and co-workers has been structurally studied . This complex was claimed to be Fe(0), but no theoretical or Mössbauer studies were carried out to prove this, and it was subsequently shown by Wolf and co-workers that naphthalene has the propensity to behave in a noninnocent fashion in a variety of low-valent iron complexes, drawing the assignment of the oxidation state of iron in [P 2 Fe(η 6 -napthalene)] into quesiton .…”

“…The occupied HOMO is predominantly a reflection of the π-back-donation from the Fe(0) center to the carbene carbon atoms of the chelating NHC, suggesting a rather strongly bound carbene; a fact also supported by the somewhat short Fe-NHC bond distances seen in the solid-state X-ray structures. This is somewhat surprising, since monodentate NHC ligands coordinated to Fe(0) centers are known to behave in a rather labile manner and undergo reversible coordination, and this therefore further underlines the inherently different bonding mode of the chelating NHC in 3 and 4 to the related existing complexes bearing redox active bis-imine or innocent bis-phosphines as supporting ligands. Finally, the HOMO-1 orbital is essentially a reflection of the π-arene interaction between the arene ring and the Fe(0) center.…”

Aromaten(phosphan)metall‐Komplexe, I. Die Vorstufen zur Synthese der Metall‐Basen ArM(PR3)2 und ArM(PR3)L (M = Ru, Os)

“…Ber. 115 (1982) Darstellung der Komplexe ArRuC12(CO) (8,9) [C&&uCI(L)(ac)]PF6 (10 -12): Zu 1.5 mmol C6H,RuC12(PR3) (PR, = PMe,, PMe2Ph, PPh,) in 10 ml Aceton wird bei Raumtemp. langsam eine Losung von Tab.…”

Late Transition Metals, Metal Halides, Metal Oxides, and Metal Sulfides (Group VIII)

“…98 In the Fe case, cyclododecatriene-Ni / PF 3 and P(OCH 3 ) 3 \ also bis(l,3-butadiene)Fe-L derivatives can be formed if L (PF 3 or CO) is added at low temperature to the diene-Fe matrix. 113 M. L. H. Green and co-workers have briefly investigated the capacity of Fe, Co, and Ni atoms to oligomerize 1,3-butadiene. 114 ' 115 Benzene and diluent were also simultaneously deposited, and presumably arene-Μ complexes are intermediates.…”