ON THE MECHANISMS OF FLUXIONALITY AND ISOMERIZATION OF [FE3(CO)12-N(P(OME)3)N] (N = 1-3)

Possible alternative mechanisms based on the ligand polyhedral model have been examined to account for the dynamic behaviour and isomerisation of the triiron derivatives [Fe3(CO)12-n{P(OMe)3}n] (n = 1-3). Carbonyl scrambling is considered to occur via two fundamental processes. First, a low-energy libration of the metal cluster unit within the ligand polyhedron and secondly, a higher-energy ligand polyhedral interconversion involving an anticubeoctahedral ligand array as the complementary geometry. Isomerisation is also believed to occur via related ligand polyhedral rearrangements.