364376-99-8Relevant academic research and scientific papers
Versatile behaviour of iron-arylcarbene complexes towards alkoxides: C-Cl and C-C bond activation reactions
Ferré, Karine,Poignant, Géraldine,Toupet, Loic,Guerchais, Véronique
, p. 19 - 27 (2007/10/03)
The Cp-containing carbene complexes [Fe(C5H5)(CO){κ2(C,O)C(OMe)C 6H4-o-OMe}][OTf] (2) and [Fe(C5H5)(CO)(CH3CN){C(OMe)C6H 4-o-Cl}[OTf] (3) have been synthesised and characterised. Complex 2 has been characterised by a single-crystal X-ray diffraction analysis; the Fe-O distance of 2.045(5) A? suggests a rather strong bonding of the methoxy group. Substitution of one carbonyl ligand by PPh3 allows the isolation of the chelate complex [Fe(C5H5)(PPh3){κ 2(C,Cl)C(OMe)C6H4-o-Cl}][OTf] (4). The reaction of [Fe(C5Me5)(CO){κ2(C,Cl)C(OMe)C 6H4-o-Cl}][OTf] (5) with alkoxides RONa (R=Me, Et) affords the chelate complexes [Fe(C5Me5)(CO){κ2(C,O)C6H 4-o-C(OMe)(OR)(OR)}] 7 (R=Me) and 8 (R=Et), respectively. Similarly, the reaction of 3 with EtONa affords [Fe(C5H5)(CO){κ2(C,O)-C6H 4-o-C(OEt)(OEt)2}] (9), for which the Ar-Cl bond has been cleaved. No activation of the Ar-Cl bond is observed for the unchelated complex [Fe(C5Me5)(CO)2{C(OMe)C6H 4-o-Cl}][OTf]. In contrast, treatment of the anisyl derivative [Fe(C5Me5)(CO){κ2(C,O)C(OMe)C 6H4-o-OMe}][OTf] (6) with EtONa gives selectively the carbene complex [Fe(C5Me5)(CO)(C6H 4-o-OMe){=C(OEt)2}] (12). The Ar-OMe bond remains intact, but cleavage of the Cα-CAr bond occurs. This rearrangement process, i.e. α-elimination of the anisyl substituent, is favoured by the lability of the ortho-OMe group. Treatment of 2 with NaOEt gives as the only identified compound the ethyl ester [MeOC6H4-o-(CO)OEt]. Clean formation of the methyl ester derivative [MeOC6H4-o-(CO)OMe] is observed upon oxidation of 2 with C6H5I+O-.
