Bridged multiclusters derived from the face-capped octahedral [Re6 III(μ3-Se)8]2+ cluster core

The face-capped octahedral cluster cis-[Re6(μ3-Se)8(PEt3)4(MeCN)2](SbF6)2, site-differentiated with protecting PEt3 and substitutionally labile MeCN ligands, reacts with bidentate ligands (L) 4,4′-bipyridyl, (E)-1,2-bis(4-pyridyl)ethene, and 1,2-bis(4-pyridyl)ethane to give the first examples of cluster-based molecular squares of the general formula cyclo-[Re6(μ3-Se)8(PEt3)4L]4(SbF6)8. The complexes were characterized by microanalysis, 1H and 31P NMR, and time-of-flight electrospray ionization mass spectrometry. Cyclic voltammetry reveals in each case one quasi-reversible oxidation and, for two compounds, one reversible and one irreversible reduction process.