Structural and electronic analysis of lanthanide complexes: Reactivity may not necessarily be independent of the identity of the lanthanide atom - A DFT study

Density functional theory calculations were used to study a given complex for the whole series of lanthanide cations: [Ln(C3H5) Cp(OMe)] (1) [Ln = La (Z = 57)- Lu (Z = 71)], the radioactive lanthanide promethium (Z = 61) excepted. Contrary to the common assumptions, the calculations suggested a significant, albeit indirect, contribution of f electrons to bonding. Relativistic effects were considered in the calculations of the bonding energies, as well as in geometry optimizations in both spin- restricted and unrestricted formalisms. The unrestricted orbitals were finally used for the analysis of the charges and the composition of the frontier orbitals. It was confirmed that the ionic character was more pronounced for complexes of the late lanthanides.