Stable Mixed-Valent Radicals from Platinum(II) Complexes of a Bis(dioxolene) Ligand

Three diplatinum(II) complexes [{PtL}(2)(μ-thea)] (H(4)thea=2,3,6,7-tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene) have been prepared, with diphosphine or bipyridyl “L” co-ligands. One-electron oxidation of these complexes gave radical cations containing a mixed-valent [thea[Image: see text]](3−) ligand with discrete catecholate and semiquinonate centers separated by quaternary methylene spacers. The electronic character of these radicals is near the Robin–Day class II/III border determined by UV/Vis/NIR and EPR spectroscopies. Crystal-structure determinations and a DFT calculation imply that oxidation of the thea(4−) ligand may lead to an increased through-space interaction between the dioxolene π systems.