Uranocenium: Synthesis,Structure, and Chemical Bonding

Abstraction of iodide from (η⁵‐C₅ⁱPr₅)₂UI] ( 1 ) produced the cationic uranium(III) metallocene (η⁵‐C₅ⁱPr₅)₂U]⁺ ( 2 ) as a salt of B(C₆F₅)₄]^?. The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non‐negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process.