The reaction of isomerized butadiene(dicarbonyl)[ethoxy(aryl)carbene]iron complex (I; R = Ph, p-tolyl) with triphenylphosphine and tri-Ph phosphite gave products II (same R; R1 = Ph, OPh), at -60 to -30? When I (R = Ph) was reacted with triphenylphosphine in hexane at 60 to 70?in addition to II (R = R1 = Ph), a diphosphine coordinated product III was also obtained. Isomerized isoprene(dicarbonyl)[ethoxy(aryl)carbene]iron complex reacted with tri-Ph phosphite to give an orange-yellow crystalline compound IV. The x-ray diffraction study of IV showed that an interesting change of the bonding of the diene ligand took place; namely, the original p-allyl moiety of the iron complex was changed to a more profoundly conjugated triene system including the aromatic ring and formed an h4 ligand, in order to satisfy the 18 electronic rule.

Key words: BUTADIENE, SUBSTITUTION REACTION, IRON COMPLEX, CARBONYL COMPOUNDS, TRIPHENYLPHOSPHINE, TRANSITION METAL COMPLEX, ADDITION REACTION, ISOPRENE, ISOMERIZATION, PHOSPHORUS ACID ESTERS