Metal thiolates structure

Robbins, A.H. and Stout, C.D. (1992) Metallothioneins Synthesis, Structure and Properhes of Metallothioneins, Phytochelatins, and Metal-Thiolate Complexes (eds M.l. ShDman, C.F. Shawlll and KT. Suzuki), VCH Publishers, Weinheim, pp. 31—54. 

Biomimics of noncatalytic, or structural, zinc generally focus on zinc-thiolate clusters designed after the metal—thiolate clusters of metal-lothionein (see Section IV,C). Adamantoid anions of formula [ (jiz-SPh)6(ZnSPh)4] are targets of synthetic and structural study, where each metal ion is coordinated in tetrahedral fashion by bridging and terminal thiolate ligands (see Hencher et al., 1985 Dean and Vittal, 1987, and references cited therein). 

Since aromatic amino acids and cysteine are absent, there is no protein absorption above 270 nm. Metallothioneins exhibit a broad absorption peak, with the maximum at 190 mn. Absorptions due to the metal-thiolate complexes show as shoulders at 250 nm (Cd), 220 nm (Zn) and 270 nm (Cu).1458,1459 Theoretical predictions based on the amino acid sequence of the peptide chain indicate that the or-helical conformation is forbidden, and /3-structure is almost impossible to attain. CD and NMR studies on both the metal-containing and metal-free protein confirmed the predictions.1459 1460 However, metallothioneins are stable to tryptic digestion and the slow exchange of many peptide hydrogens of metallothionein with those of the solvent suggest that the protein has a compact and well-defined tertiary structure. 

Stillman MJ, Shaw CF III, Suzuki KT (1992) Metallothioneins. Synthesis, structure, and properties of metallothioneins, phytochelatins and metal-thiolate complexes. VCH Publishers, New York Stratford IJ, Hoe S, Adams GE, Hardy C, Williamson C (1983) Abnormal radiosensitizing and cytotoxic properties of ortho-substituted nitroimidazoles. Int J Radiat Biol 43 31-43 Stubbe J, Kozarich JW (1987) Mechanisms of bleomycin-induced DNA degradation. Chem Rev 87 1107-1136... 

X-ray structure analysis revealed the structures of [NiFe] and [FeFe] hydrogenases and established the metal thiolate coordination in their active centers. Scheme 33 depicts the active centers (138, 139). 

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)... 

M. J. Stilhnan, C. F. Shaw 111, and K. T. Suzuki eds, Metallothioneins Synthesis, Structure, and Properties of Metallothioneins, Phytochelatins and Metal-thiolate Complexes , VCH, New York, 1992. 

The synthesis, structures, and reactivities of metal thiolates with group 4 and 5 metals, and the synthesis and study of copper-thiolates have been reviewed. Hg thiolate chemistry has been reviewed and related to the binding of Hg in vivo by metalloregulatory proteins. A range of two-, three-, and four-coordinate Hg thiolate complexes has been prepared, and comparisons with the metalloregulatory protein, Hg-MerR,... 

It has long been known that thiolate ligands (RS ), which are formally derived from thiols (RSH) by deprotonation, are well suited to form metal complexes (1). Specific reviews of this area have covered the structural chemistry of metal thiolates (la), the coordination chemistry of metal thiolates from a bioinorganic perspective (lb), transition metal thiolates (lc), and, most recently, early transition metal thiolates (Id). Because of potential thione-thiol tautomerism, a review dealing with complexes of heterocylic thione donors (le) is also relevant. This chapter concentrates on thiolate complexes of copper , lithium, and magnesium, but we also mention, for comparison or contrast, many related species of silver and gold and of some complexes that contain selenolate and tellurolate ligands. However, it should be emphasized that we have not attempted a comprehensive literature search outside the primary field of interest. 

The next increase in aggregation state of Group 11 (IB) metal thiolates affords pentameric structures, but to the best of our knowledge a structurally characterized species of this type is unknown. In organocopper(I) chemistry, the only example is that of mesitylcopper [Cu5(C6H2Me3-2,4,6)5] (125), which has a structure based on an open Cu5C5 10-membered heterocycle. 

Reports that thermolysis of metal chalcogenolate complexes offers a low-temperature route to the synthesis of novel solid state materials (32) is also stimulating research in this area. As is the case with copper(I) thiolates, lithium thiolates are often aggregated species (Section III.C) and from the few magnesium thiolate structures known (Section III.D) one sees a preference for monomeric and dimeric formulations when bulky substituents are present. 

Whereas studies of the structures of transition metal thiolate complexes are quite numerous, analogous studies with complexes of the more electropositive... 

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