STUDY OF THE NUCLEOPHILIC-ADDITION OF ALCOHOLATES ON CIS-FE(R)(R')(CO)(3)L (R,R'=ALKYL, ALKOXYCARBONYL, ALKYLOXALYL L=CO, P(OET)(3)) AND THE FIRST CHARACTERIZATION OF A TRIS(ALKOXYCARBONYL) COMPLEX - K[FE(CO(2)TBU)(3)(CO)(3)]

The nucleophilic additions of alcoholates.(MeONa or tBuOK) on the comp lexes cis-Fe(R)-(R')(CO)(3)L (R, R' = CO(2)Me, CO(2)tBu, CH(2)CO(2)Me, COCO(2)Me; L = CO, P(OEt)(3)) occur at one terminal carbonyl ligand t o give the new [Fe(R)(R')(CO(2)R '')(CO)(2)L](-) anions. No transester ification (via addition at an alkoxycarbonyl ligand) is observed. An X -ray diffraction study gives the space group P2(1)/c for K[Fe(CO(2)tBu )(3)(CO)(3)] (resulting from the addition of KOtBu on Fe(CO(2)tBu)(2)( CO)(4)), which is better described as the dimer K2Fe2(CO(2)tBu)(6)(CO) (6) . H2O .-THF.