EFFECT OF THE LIGAND L ON THE TRANSESTERIFICATION PROCESSES OF BISMETHOXYCARBONYL IRON COMPLEXES - CIS FE(CO2ME)(2)(CO)(3)L, L = CO, PME3, PPH3, P(OET)(3)
M. Sellin et al., EFFECT OF THE LIGAND L ON THE TRANSESTERIFICATION PROCESSES OF BISMETHOXYCARBONYL IRON COMPLEXES - CIS FE(CO2ME)(2)(CO)(3)L, L = CO, PME3, PPH3, P(OET)(3), Journal of organometallic chemistry, 562(2), 1998, pp. 183-189
The synthesis of the new mer or fac Fe(CO2Me)(2)(CO)(3) (L) (L = PMe3:
2a; L = PPh3: 2b; L = P(Cy)(3): 2c; L = P(OEt)(3): 2d) complexes of v
arious electron densities has been realized in order to study the tran
sesterification reactions between these methoxycarbonyl complexes and
alcohols. The easy formation of [Fe(CO2Me)(CO)(4)(L)] [BF4] by removin
g a methoxy group from these complexes clearly indicates that their me
thoxy group and particularly the one trans to the phosphane ligand are
mobile. However whereas the unsubstituted complex Fe(CO2Me)(2)(CO)(4)
(1) presents fast exchange reactions with ethanol, 2a and 2b are foun
d unreactive towards the same reagent and 2d (L = P(OEt)(3)) only unde
rgoes slow transesterification reactions at 28 degrees C. It is propos
ed an associative mechanism for this transesterification process proba
bly induced by a preliminary nucleophilic addition of an alcohol molec
ule at a terminal carbonyl ligand prior to the elimination of the meth
oxy group of a methoxycarbonyl. (C) 1998 Elsevier Science S.A. All rig
hts reserved.