Thiolates cluster chemistry

At present, our knowledge about the structure of the Cu -containing manunahan MT-1 and MT-2 isoforms is limited to the fact that fully Cu-loaded MT form contains 12 Cu ions organized in two metal-thiolate clusters, where, in contrast to divalent metal ions, the monovalent copper ions are coordinated by two or three cysteine ligands (see Copper Inorganic Coordination Chemistry)... 

As the field of metal carbonyl cluster chemistry was expanding rapidly many other new classes of clusters joined the fold, in particular, gold phosphine clusters, metal-alkoxide, -thiolate, and -halide clusters of the early transition elements. The theories of bonding in metal clusters rapidly advanced aided by both computational procedures and conceptual ideas. Without a doubt the most significant in the latter... 

Abstract There have been remarkable advances in the development of gold nanoclusters protected by thiolates (Au (SR)m), and techniques for the synthesis and characterization of these materials have improved significantly, enabling Au (SR)m to be synthesized with atomic precision. Experiments on the stabilities of clusters synthesized in this way have revealed a series of magic clusters, and the structures and physical and chemical properties of these magic clusters have subsequently been elucidated. Furthermore, several methods have been established for the functionalization of magic clusters. This chapter describes recent developments in Au (SR)m cluster chemistry. 

Yet another possibility involves H2 activation at thiolate ligands. This possibility is suggested by the chemistry of an Fe11 tetrathiolate complex (Scheme 4) (110), which evolves H2 when H+ is added to the system. Intermediates proposed for this reaction include thiol complexes derived from the protonation of the thiolate ligands. A role for a metal cluster in the catalysis is also suggested by the mechanism, which involves the formation of dimeric species in order to provide the two electrons necessary for the production of H2. 

A chemistry of cobalt-sulfide-thiolate molecular clusters comparable with that of iron systems has also begun to emerge. Treatment of [Co4( -SPh)6(SPh)4]2- with HS- in acetone affords the octanuclear cluster [Co8(ji4-S)6(SPh)8]4 isolated as its Pr4N+ salt.988 In MeCN solution the complex is red-purple with intense sulfur-core charge transfer bands which obscure the Co" d-d transitions. This behaviour contrasts with that of both mono- and poly-nuclear cobalt"-thiolate complexes, which all display LMCT bands below 440 nm and have well-developed v2 and v3 features. The [Co8(/j4-S6)]4+ core sustains reversible one-electron oxidation and reduction (E]l2 = —0.54, — 1.18 V, MeCN) and chemical reduction with sodium acenaphthylenide in THF gives [Co8(/r4-... 

This is a remarkable reaction because the transition metal chemistry of N2O is sparse, especially with copper. Most N2O reductases are soluble, periplasmic homodimers however, there are examples of membrane-associated enzymes. " The best characterized N2O reductases are from Paracoccus denitrificans, Pseudomonas nautica, and Pseudomonas stutzeri, and most of the information presented here is derived from experiments on these enzymes. Where comparable data are available, N2O reductases from various organisms appear to be fairly similar, with the exception of the enzyme from Wolinella succinogenes, as noted above. The crystal stractmes of N2O reductase from P. nautica and more recently from P. denitrificans show two distinct copper clusters per subunit a bis-thiolate bridged dinuclear electron-transfer site (Cua), which is analogous to the Cua site in cytochrome c oxidase see Cyanide Complexes of the Transition Metals), and a novel four-copper cluster ligated by seven histidines, the catalytic copper site (Cuz), where N2O is thought to bind and be reduced. Cuz was proposed to be a copper-histidine cluster on the basis of the presence of nine strictly conserved histidine residues, and this was supported by a H NMR study that identified two non-CuA associated resonances that were assigned as copper-histidine N-H protons. ... 

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