Tetranuclear thiolates

Thiols like pyridine-2-thiol yield (carbene)gold thiolates, and onium salts give cationic (carbene)gold ylide complexes, isolated and characterized as the perchlorates.170 The reaction of dithiocatechol with (cyclohexylisocya-nide)gold chloride affords a carbene complex [(CyNC)AuC(NHCy)2]+Cl-, which co-crystallizes with a neutral tetranuclear complex [(CyNCAu)2Au2(S2C6H4)2].224... 

Kockerling, M. and Henkel, G. (2000) Synthesis and structure of [Ni4(S2C7Hio)4], the first tetranuclear cyclic nickel complex with bifunctional thiolate ligands and of the mononuclear precursor compound Na2[Ni(S2C7Hio)2]- 4MeOH. (PrOH)-Pr-i, Inorg. Chem. Commun., 3, 117-9. 

Butler, A. R., Glidewell, C., Hyde, A. R., and Walton, J. C. (1985). Formation of paramagnetic mononuclear iron nitrosyl complexes from diamagnetic di- and tetranuclear iron-sulphur nitrosyls Characterization by EPR spectroscopy and study of thiolate and nitrosyl ligand exchange reactions. Polyhedron 4, 797-809. 

It is instructive, in this context, to compare the case of assembly of both nitrosylated iron sulfur tetranuclear clusters and the related clusters with pendant thiolate groups (13), with the laborious and stepwise initial synthesis (38) of cubane C8H8 this comparison is, of course, simply one between thermodynamically controlled processes, in the case of the iron sulfur systems, and kinetically controlled reactions for C8H8 synthesis. 

On the basis of the analysis of EPR, optical, and MCD data, the catalytic Cu center of N2OR was proposed to be a second binuclear center with cysteine coordination. When msZ DNA sequences revealed that there were an insufficient number of conserved Cys residues to bind two thiolate-bridged centers, coordination by a set of conserved histidine residues was suggested. This suggestion was subsequently confirmed by the crystal structures of N2OR. What was completely unexpected was the tetranuclear nature of the Cu site, which had remained undiscovered despite expensive spectroscopic study. The recognition of the tetranuclear structure of the Cu center provided a framework for the interpretation of the spectroscopic data. 

Our approach to the preparation of new imido clusters of rhodium consists of the reactions of equimolar quantities of [ Rh( -Cl)(diolefin) 2] with a solution, prepared in situ, by the addition of butyl lithium to ara-toluidine in a 2 1 molar ratio in diethyl ether. At first glance, a hypothetical trinuclear cluster of formulation [Rh3(/i-N-p-tolyl)2(diolefin)3] could be expected from these reactions on the basis of the formation the isoelectronic thiolate complexes [Rh3(//-SPh)2(diolefin)3]+. However, unexpectedly, the results of these one-pot reactions were the formation of the novel tetranuclear clusters [Rli4( u-N-/7-tolyl)2(diolefin)4] diolefin = 1,5-cyclooctadiene (cod) (1), tetrafluorobenzobarrelene (tfb) (2), isolated as dark-red crystalline solids in good yields. 

Several other tetranuclear iron-sulfur cluster compounds of general formula [Fc4S4X4]" ", in which X is a non-thiolate terminal ligand, have been studied in some detail. These include systems in which X = Cl, NO and dithiolene. The structure of the dianion [Fe4S4Cl4] " has been... 

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