Studies on the synthesis, spectra and structure of isomerized products of isopentadiene(dicarbonyl)‐[ethoxy(aryl)carbene]iron complexes and the crystal structure of tetracarbonyl[ethoxy‐(pentachlorophenyl)carbene]iron

Reaction of π‐isopentadienetricarbonyliron (1) with aryl lithium ArLi (Arphenyl, p ‐tolyl, p ‐methoxyphenyl, p ‐trifluoromethylphenyl) in ether at low temperature, and subsequent alkylation of the acylmetallate formed with triethyloxonium tetrafluoroborate[(C 2 H 5 ) 3 OBF 4 ] in aqueous solution at 0°C, gave orange‐red crystalline complexes (2‐5), the isomerized products of isopentadiene (dicarbonyl) [ethoxy(aryl)carbene] iron with composition of C 5 H 8 (CO) 2 FeC(OC 2 H 5 )Ar When LiC 6 Cl 5 was used as nucleophilic reagent in the reaction, on alkylation of the afforded acylmetallate intermediate under some reaction conditions, complex (CO) 4 FeC(OC 2 H 5 )C 6 Cl 5 (6) was obtained. The molecular structure of complexes 2 and 6 were determined by means of single crystal X‐ray diffraction measurements. IR, 1 H NMR and mass spectra of these complexes were investigated.