Preparation of Metal-Sulfur Clusters from Trinuclear Precursors

2 Preparation of Metal-Sulfur Clusters from Trinuclear Precursors 

Among the clusters derivatized by these methods, [ Mo(tacn) 3(PdCl)(n3-S)4]3+ (tacn = 1,4,7-triazacyclononane) is noteworthy, since this cluster can bind the substrate molecules such as alkene and CO at its tetrahedral Pd site generated by dissociation of the Cl anion. More interestingly, it has turned out that addition of ROH and RCOOH to various alkynes proceeds at this Pd site to give vinyl ethers and vinyl carboxylates catalytically.53 These reactions represent one of the yet rare examples that are catalyzed by well-defined cubane-type clusters with retention of their core structures. 

Incomplete cubane-type p-sulfido-p-hydrosulfido cluster [(Cp Ir)3(p3-S)(p2-SH)3]+ can also be used as the precursor to the mixed-metal cubane-type 

Syntheses of cubane-type MFe3S4 clusters using a linear or incomplete cubane-type Fe3S4 clusters 

Metal-sulfur aggregates are now known to occur in biological systems as the active sites of a significant number of metalloenzymes, and clarification of their detailed structures are currently progressing rapidly. In consideration of the results of these studies, many researchers are attempting to synthesize the direct structural models as well as the functional models of the active sites of natural enzymes that promote various important reactions in the biological systems under ambient conditions, which presumably leads in the near future to the 

SchlOgl, Angew. Chem. Int. Ed., 2003, 42, 2004 b) G.J. Leigh, in Catalysts for Nitrogen Fixation, B.E. Smith, R.L. Richards and W.E. Newton (eds), Kluwer Academic Publishers, Dordrecht, 2004, 33 (c) M. Appl, Ammonia, Wiley-VCH, Weinheim, 1999. 

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