Páez Hernández, DayánSolis Céspedes, Eduardo2024-10-172024-10-172018https://repositorio.unab.cl/handle/ria/61347Tesis (Doctor en Fisicoquímica Molecular)The development of new lanthanide materials with special magnetic properties has been in the last decades a tapie with a vertiginous advance. The high chemical modifiability of the constituting molecules makes such materials highly versatile, and the small size of the building blocks leads to the rise of various quantum mechanical phenomena. This work describes the computational and theoretical studies in the field of molecular magnetism using state-of-the-art quantum chemical methods based on ab-initio multireference approaches. In a first step the methodology is proposed and applied to describe the role of the ligand environment on the Kramers doublets derived from the 6H1s12 ground configuration of the Dysprosium (Dy3+) ion in its complexes; concluding that in the case of lanthanides whose electron distributions are oblate (squashed along the axial direction), such as terbium, dysprosium and holmium, an axial position of the ligand electrons is particularly favorable for generating a sizeable magnetic anisotropy. In the second work a theoretical model is proposed to model the electronic states and magnetic properties derived from the f1 configuration. This model was applied to lanthanocene and actinocene compounds, showing the important role of the symmetry in the study of the magnetic properties. Finally, a theoretical insight in the superexchange mechanism of coupling in a f1 -f1 system is presented for Ce2(COT)3 compound; an altemative mechanism for the superexchange between the two f1 lanthanide centers is presented considering the 5dz 2 orbitals. In ali cases the computational tools offer more insight into the electronic structure and chemical properties of the systems, giving rise a better understanding of the causes of the various observed magnetic phenomena. The results contribute to our understanding of magnetically interesting molecular systems and suggest new details to take into account in the fíeld.esAnisotropíaComplejos LantánidosTesis