Metal-Organic Frameworks with d-f Cyanide Bridges: Structural Diversity, Bonding Regime, and Magnetism

We present a selection of metal-organic frameworks based on d-f and f-f linkages, discussing their structural features and properties from experimental and theoretical viewpoints. We give an overview of our own synthetic and modeling methodologies, highlighting the complexity of the interdisciplinary approach developed. Significant experimental and computational strategies of other researchers are also reviewed. The bonding regime of lanthanide units in MOFs is similar to those encountered in mono-or polynuclear f-type coordination compounds. However, the steric demands of constructing a three-dimensional network determine specific ligand composition and topologies at the local f nodes. Due to weak interaction propensity of the inner shell f orbitals, the electronic structure treatments of lanthanide units require certain conceptual and technical subtleties. With proper handling, multiconfiguration wave function approaches as well as density functional theory (DFT) treatments can be analyzed in terms of meaningful ligand field (LF) modeling. The interplay of LF and spin-orbit (SO) effects in determining the magnetic anisotropy is illustrated, after reviewing the experimental magnetic behavior of several d-f cyanide-bridged systems.