A Theoretical Assessment of Spin and Charge States in Binuclear Cobalt-Ruthenium Complexes: Implications for a Creutz-Taube Model Ion Separated by a C60-Derivative Bridging Ligand

A novel symmetric pyrazine (pyz)-bridged uranyl dimer [UO2Cl3(H2O)(Pyz)0.5]22-: synthesis, structure and computational analysis

Herein we report on the synthesis of (HPyz⁺)₂[UO₂Cl₃(H₂O)(Pyz)_0.5]₂·2H₂O which features a novel pyrazine-bridged uranyl dimer, [UO₂Cl₃(H₂O)(Pyz)_0.5]₂^2-. A rigorous computational and experimental analysis of this compound was performed to fully explore the influence of coordination on the electronic structure and potential charge-transfer characteristics of this dimer, revealing a delocalized π-system across the bridging pyrazine and the axial components of both uranyl centers. Electrostatic surface potentials, used to rationalize the observed assembly, indicate a decreased basicity of the uranyl oxo versus [UO₂Cl₄]^2-, and signify a lessened capacity for the terminal -yl oxos of the [UO₂Cl₃(H₂O)(Pyz)_0.5]₂^2- dimer to participate in supramolecular assembly. A combined density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) analysis further evidenced an increase in UO bond strengths within the dimer, which is supported by a blue shift in the characteristic Raman-active uranyl symmetric stretch (ν₁) with respect to the more typically observed [UO₂Cl₄]^2-.