Bond shift isomerization in cyclic and acyclic (triene)Fe(CO)3 complexes. A density functional study

The 1,3-metal shift process has been studied for several conjugated cyclic and acyclic (η4-triene)Fe(CO)3 systems. In all cases the transition state of the process corresponds to (η2-triene)Fe(CO)3 structures. The computed energy barriers are notably higher for acyclic complexes than for the cyclic ones, in good agreement with the experimental observations. The analysis of the energy barriers shows that this is due to the different orientations of the triene ligand in the transition states, which leads to more efficient stabilizing metal-ligand orbital interactions for the cyclic systems.