p-Carborane: a New Cage Spacer for Photoactive Metal Polypyridine Dyads

The first example of a binuclear ruthenium complex involving the p-carborane framework in the bridging ligand is reported. The bridging ligand is a symmetric linear array comprising a central p-carborane unit, two p-phenylene spacers, and two 5-yl-2,2¢- bipyridine coordinating units. A homobinuclear RuII complex, with 2,2¢-bipyridine as peripheral ligands, was synthesized and characterized. The RuII-RuIII mixed-valence species, obtained by partial oxidation, has been investigated with steady-state and time-resolved techniques in CH3CN. The rate of photoinduced electron transfer is 2.3 ´ 108 s-1.