Clusters, metal biological relevance

Keywords Noncovalent interactions Cation-n n-n stacking Hydrogen bonding Molecular clusters Cooperativity Biological relevance of metal ion interactions... 

Because of possible catalytic and biological relevance of metal-sulfur clusters, several such compounds of cobalt have been prepared. The action of H2S or M2S (M = alkali metal) on a non-aqueous solution of a convenient cobalt compound (often containing, or in the presence of, a phosphine) is a typical route. Diamagnetic [Co6Ss(PR3)6] (R = Et, Ph) comprise an octahedral array of metal atoms (Co-Co in the range 281.7 to 289.4pm), all faces capped by atoms,and show facile redox behaviour... 

The nse of polysnlfide complexes in catalysis has been discnssed. Two major classes of reactions are apparent (1) hydrogen activation and (2) electron transfers. For example, [CpMo(S)(SH)]2 catalyzes the conversion of nitrobenzene to aniline at room temperature, while (CpMo(S))2S2CH2 catalyzes a number of reactions snch as the conversion of bromoethylbenzene to ethylbenzene and the rednction of acetyl chloride, as well as the rednction of alkynes to the corresponding cw-alkenes. Electron transfer reactions see Electron Transfer in Coordination Compounds) have been studied because of their relevance to biological processes (in, for example, ferrodoxins), and these cluster compounds are dealt with in Iron-Sulfur Proteins. Other studies include the use of metal polysulfide complexes as catalysts for the photolytic reduction of water by THF and copper compounds for the hydration of acetylene to acetaldehyde. ... 

The ability of tetrachalcogenometallates [ME4]" (M = V, Nb, = 3 M = Mo, W, n = 2 M = Re, n= 1) to act as multidentate ligands to a variety of transition metals has been well documented. " As a result of this coordinative versatility, these complexes have been widely implemented in the synthesis of homometallic and heterometallic metal chalcogenide clusters with intact or altered [ME4] - units. In particular, the synthesis of ternary polynuclear M-Fe-E and M-Cu(Ag)-E complexes has received much attention, due to their relevance to biological systems as well as interesting catalytic and physical properties. 

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