Reactions of Fe3(CO)12 and Fe(CO)5 with functionalized alkynes in CH3OH–KOH solution — The crystal structure of Fe2(CO)6(PPh3)[µ-η3-(H2CCCH2)]

Abstract

The complex Fe2(CO)7(H2CCCH2) (1) is obtained starting from a variety of functionalized alkynes that can release C3 fragments during the reactions with Fe3(CO)12 or Fe(CO)5 in CH3OH–KOH solutions. Owing to the oily nature of 1, it was reacted with triphenylphosphine, and the structure of the resulting title compound (1a) has been determined by X-ray analysis. Complex 1a shows a new coordination mode of a H2C=C=CH2 ligand to a diiron centre and is, to our knowledge, unprecedented. We have also found that 1 (and 1a) are by-products, and not intermediates in the formation of complex 3. A discussion of the possible reaction pathways is given.Key words: iron carbonyls, alkynols, CO and methanol activation, acetyl and acetate complexes, allenyl iron complexes, crystal structure.