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 ReLF (1, L = hexahydro-2H-pyrimido[1,2a]pyrimidinate (hpp); 2, L = diphenyl formamidinate (dpf)) were prepared from the solid-state melt reactions (SSMRs) between (NH)[ReF]·2HO and HL. 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 [Re(hpp)F]PF (3) was prepared from the one-electron oxidation of Re(hpp)F with [CpFe]PF. Compounds 1-3 are isostructural with the corresponding chloro derivatives. In solution, compound 1 undergoes two one-electron oxidations. Comparison with its higher halogen homologues reveals that Re(hpp)F (1) is more easily oxidized than its chloro and bromo analogues.