Construction of Transition Metal Chalcogenide Clusters and Their Functions

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During this research project, we have made substantial progress in many phases of research items, viz,1. We have synthesized a novel rhenium selenido cluster, of [Cp^*Re(Se_3)(μ-Se_2)]_8, having a octa-nuclear diamond-crown shape of [Re(μ-Se_2)]_8 24-membered macrocyclic core, from the reaction of Cp^*ReCl_4 with 2-3 equiv of Li_2Se_5. On the other hand, the analogous reaction between Cp^*ReCl_4 and 2 equiv of Li_2Te_5 gave rise to a trinuclear cluster of a birdcage shape, Cp^*3Re_3Te_8.2. A series of alkynethiolato complexes, alkyneselenolato complexes, diynethiolato complexes have been synthesized. These thiolate ligands are unique in that they carry unsaturated C-C bonds as substituents, and have shown interesting reactivity at various transition metal centers. For instance, we found unusual C-C coupling reactions, cyclic dimerizatino/trimerization of the functional carbon sites, C-S bond cleavage occurring at the thiolate ligands.3. Thiolate-type sulfur is coordinated at transition … More metal centers relatively strongly, while thioether-type sulfur forms weak M-S bonds, often exhibiting facile dissociation equilibration. We have utilized the mixed ligands RSCH_2CH_2S(-) (R=Et (etet), R=^iPr (^1ptet), R=Ph (ptet)) for assemblage of iron(II) and Ni(II) metal atoms. For instance, the 1:2 NiCl_2/Li(etet) reaction system gave rise to a linear polymer [Ni(etet)_2]_n, while the analogous 1:2 NiCl_2/Li(ptet) reaction resulted in formation of a cyclic hexamer [Ni_6(ptet)_<12>]. An interesting feature of these 1-dimensional polymers of Ni and Fe is that they can be dissolved in toluene by virtue of coordination of thioether-type sulfur atoms, and that the polymer structures are regenerated upon recrystallization.4. A series of sulfido-bridged tungsten-ruthenium dinuclear complexes Cp^*W(μ-S)_3RuX(PPh_3)_2, Cp^*W(O) (μ-S)_2RuX(PPh_3)_2, and Cp^*W(NPh) (μ-S)_2RuX(PPh_3)_2 have been synthesized. The heterolytic cleavage of H_2 was found to proceed at room temperature upon treating Cp^*W(O) (μ-S)_2RuX(PPh_3)_2 and Cp^*W(NPh)(μ-S)_2RuX(PPh_3)_2 with NaBArF_4 under atmospheric pressure of H_2, which gave rise to [Cp^*W(OH)(μ-S)_2RuH(PPh_3)_2](BarF_4) and [Cp^*W(NHPh)(μ-S)_2RuH(PPh_3)_2](BarF_4), respectively. The mechanism of the heterolytic H_2 activation and the reverse H_2 evolution reactions have been investigated. Less