Expanding the Chemistry of Rhenium Metal–Metal Bonded Fluoro Complexes: Facile Preparation and Characterization of Paddlewheel Complexes

Quadruply bonded rhenium(III) dimers with the stoichiometry Re₂L₄F₂ (1, L = hexahydro-2H-pyrimido[1,2a]pyrimidinate (hpp^–); 2, L = diphenyl formamidinate (dpf^–)) were prepared from the solid-state melt reactions (SSMRs) between (NH₄)₂[Re₂F₈]·2H₂O and HL. Then those compounds were characterized in the solid state by single-crystal X-ray diffraction and in solution by UV–visible spectroscopy and cyclic voltammetry. The compound [Re₂(hpp)₄F₂]PF₆ (3) was prepared from the one-electron oxidation of Re₂(hpp)₄F₂ with [Cp₂Fe]PF₆. Compounds 1–3 are isostructural with the corresponding chloro derivatives. In summation, compound 1 undergoes two one-electron oxidations. Comparison with its higher halogen homologues reveals that Re₂(hpp)₄F₂ (1) is more easily oxidized than its chloro and bromo analogues.