REACTIVITY OF 1-SUBSTITUTED (PENTADIENYL) IRON(1- REGIOSELECTIVITY FOR ADDITION OF MALONATE NUCLEOPHILES - FORMATION OF (PENTENEDIYL)IRON AND (DIENE)IRON COMPLEXES() CATIONS )

The reaction of six 1-substituted (pentadienyl)iron cations (1-6) with malonate anions was examined. The electronic nature of substituents p resent on the pentadienyl ligand, the steric bulk of the malonate anio n, and the peripheral Ligands about the iron metal were varied. (Pente nediyl)- and/or (diene)iron complexes, resulting from attack at either an internal (C2/C4) or terminal (C1/C5) pentadienyl carbon, were isol ated as products. These results indicate that strongly electron withdr awing substituents direct malonate attack at the internal pentadienyl site, while strongly electron donating substituents direct malonate at tack at the terminal pentadienyl site. The single crystal X-ray diffra ction analysis of two (pentenediyl)iron complexes (7a and 7b) are repo rted. (C) 1997 Elsevier Science S.A.