Metal-ligand bonding and metal atom dynamics in Fe-Fe and Ru-Fe triple-decker sandwich complexes

The 57Fe Mössbauer effect spectrum of [Cp′FeCp′FeCp′]BF4 (Cp′ = C5(CH3)4H (1) at 92 K shows the presence of a major quadrupole-split doublet as well as the presence of a small paramagnetic resonance ascribed to a decomposition (oxidation) impurity. The bottom trace is the difference between the theoretical fit values and the experimental data.