SUBSTITUTION-REACTIONS OF DINUCLEAR ALKENYL-BRIDGED IRON-COBALT COMPLEXES WITH PHOSPHINES - CRYSTAL-STRUCTURES OF [(CO)3FE-CO(CO)2(PME2PH)](MU-C(CO2ME)=C(CO2ME)H) AND [(CO)2(PME2PH)FE-CO(CO)2(PME2PH)]-(MU-C(CO2ME)=C(CO2ME)H)

The bridging alkenyl iron-cobalt complexes [(CO)4Fe-Co(CO)3](mu-CR1 = CR2H) (R1 = CO2Me or CO2Et and R2 = H; R1 = H and R2 = H or Ph) react with one equivalent of PMe2Ph or PPh3 to give monosubstituted complexes with the phosphine ligand coordinated to the iron atom. When R1 = CO2Me or CO2Et and R2 = H, addition of two equivalents of PPh3 produces complexes with two PPh3 ligands coordinated to each metal. The complex [(CO)3Fe-Co(CO)3](mu-C(CO2Me) = C(CO2Me)H) also reacts with one equivalent of PMe2Ph, PMePh2, PPh3 or PPh2H to give monosubstituted complexes with the phosphine ligand bonded to the cobalt atom. The reaction of the complex [(CO)3Fe-Co(CO)3](mu-C(CO2Me) = C(CO2Me)H) with PPh3 gives a complex with the phosphine coordinated to the iron atom, but addition of two phosphines gives complexes with one phosphine ligand bonded to each metal. The structures of the products [(CO)3Fe-Co(CO)2(PMe2Ph)](mu-C(CO2Me) = C(CO2Me)H) and [(CO)2(PMe2Ph)Fe-Co(CO)2(PMe2Ph)](mu-C(CO2Me) = C(CO2Me)H) obtained from the reaction of the [(CO)3Fe-Co(CO)3](mu-C(CO2Me) = C(CO2Me)H) complex with one and two equivalents of PMe2Ph, respectively, have been determined by X-ray crystallography.