Routes to metallodendrimers of the [Re(6)(mu(3)-Se)(8)](2+) core-containing clusters

The reaction of Re6(mu3-Se)8(PEt3)5(MeCN)](SbF6)2 with an excess of 1,2-bis(4-pyridyl)ethane (L1) and (E)-1,2-bis(4-pyridyl)ethene (L2) produced Re6(mu3-Se)8(PEt3)5(L1)](SbF6)2 and Re6(mu3-Se)8(PEt3)5(L2)](SbF6)2, respectively, each bearing an accessible pyridyl N atom capable of further metal coordination. Reacting these cluster complex-based ligands with Re6(mu3-Se)8(MeCN)6](SbF6)2 afforded two heptacluster metallodendrimers, each featuring a central Re6(mu3-Se)8]2+ cluster core surrounded by six units of Re6(mu3-Se)8(PEt3)5]2+ via the bridging interactions of its respective dipyridyl-based ligands. Their identity and stereochemistry have been established, with the most convincing evidence furnished by a unique 77Se NMR spectroscopic study. Electrochemical studies suggest very interesting electronic properties of these novel metallodendrimers.