CARBON-LIGAND MIGRATION DURING THE ELECTRON-TRANSFER CATALYZED STEPWISE REPLACEMENT OF 2 CARBON-MONOXIDE LIGANDS IN A DOUBLY-BRIDGE DIIRON COMPOUND

The complexes [(μ-η2-ROC(1)S)Fe2(CO)6(μ-SMe)] (1), undergo selective replacement of one CO by P(OMe)3 (L1) or t-BuNC (L2) to give the monosubstituted compounds 2 and 3, respectively when L1 or L2 is bonded to Fe(1) bearing the carbene ligand C(1). When a second CO ligand is displaced from 2 or 3 by electron-transfer catalysis both give a complex (6) in which L2 and L1 are linked to Fe(1) and Fe(2), respectively; moreover L1 in 2 and L2 in 3 are displaced by the ligand present in the solution to give bis-isonitriles and bis-phosphites. The structure of 6 has been determined by X-ray diffraction and the results are discussed in terms of the assumption that the ligand exchange occurs in an intermediate in which C(1) becomes bonded to both metal atoms and consequently can rotate about the Fe-Fe axis. © 1990.