DFT studies of some structures and reactions of lanthanides complexes

An account of our own DFT calculations on structures and reactions of some lanthanides complexes is given. For each of the Ln complexes the entire family, La to Lu, has been studied. Comparison between calculations with 4f electrons in the valence shell and in the core confirm the current belief that the 4f electrons are uninvolved in bonding so that 4f electrons can be included in the core. The calculations show that special care with the modeling of ligands is necessary, since oversimplification of the ligands can lead to structural artefacts. The artefacts are probably due to the large size of the lanthanide ions which favors interactions that do not necessarily represent the situation in experimental complexes. For instance agostic interactions and distortion of the coordination sphere that do not exist in the real systems are obtained when N-(SiMe3)2 is modeled by N-(SiH3)2. However, if caution is used, calculated structures agree nicely with experiment (for example, CeCl(NR2)3), R=SiMe3). The hydrogen exchange reaction, Cp2LnH*+HH→Cp2LnH+H*H, shows that in agreement with the experimental evidence, this reaction is facile for most lanthanides. Some dependence on the nature of the lanthanide metal is obtained. While currently described as a σ-bond metathesis, the reaction can also be viewed as a nucleophilic addition of H− to H2 in the field of a lanthanide ion. Calculations of structural and reactivity properties of large size lanthanides complexes for any Ln element are feasible within certain limitations that are discussed.