A series of tricarbonyl(polyene aldehyde)iron complexes

Abstract

The reaction of a series of ω-phenylpoiyenals with dodecacarbonyltri-iron affords isomeric mixtures of compounds of the general stoicheiometry [Ph(CHCH)_nCHO]Fe(CO)₃; n= 2–5. The major product is always the isomer in which the Fe(CO)₃ moiety is bonded to the butadiene fragment adjacent to the aldehyde function. The u.v. absorption spectra of the complexes indicate that the tricarbony(diene)iron unit considerably interrupts the transmission of conjugative effects along the polyene chain. The occurrence of the lowest energy absorption band at 25 400 ± 400 cm^–1(394 ± 4 nm) in the spectra of the 2,4-dinitrophenylhydrazone derivatives of the above and related aldehyde and ketone complexes is evidence for the Fe(CO)₃ and [graphic omitted]CO functions being immediately adjacent.