Thiolate ligands applications

Examples of the successful application of this method are the use of cop-per(II) acetate for the preparation of neutral complexes [Cu(SR)] (R = aryl, alkyl no base needed) (46), and the use of copper(II) nitrate for the synthesis of anionic species [Cu4(SPh))6]2 and [Cu5(SPh)7]2- (47, 48), as well as of the cationic species [Cu,(SC5H4NH)3]+ (49). The latter complex is interesting in that each thiolate ligand is neutral due to protonation of the pyridine nitrogen atom. Similarly, silver nitrate has been used to prepare several neutral alkyl-thiolato silver complexes (33). The use of copper(I) oxide was reported in the synthesis of a family of copper(I) arenethiolates containing intramolecularly... 

These characteristics of thiolate ligands means they are ideally suited for applications where two or more metal centers are to be brought together in a well-defined way. Such is the case in a number of metal complex catalyzed organic reactions where organometallic reagents are employed for C—C cou-... 

Higuchi, T. and M. Hirobe (1996). Four recent studies in cytochrome P450 modelings A stable iron porphyrin coordinated by a thiolate ligand a robust ruthenium porphyrin-pyridine N-oxide derivatives system polypeptide-bound iron porphyrin application to drug metabolism smdies. J. Mol. Catal A Chem. 113, 403 22. 

Systemic NO levels in living animals may be raised in various ways gaseous NO can be applied to exposed body surfaces like skin and lung tissue, and finds clinical application in accelerated healing of skin lesions and for treatment of pulmonary hypertension in newborn babies. Internal tissues can be reached with pharmaceutical NO donors like nitroglycerin, isoamyl nitrite, or NONO-ates that release NO in a controlled way. Paramagnetic DNICs with thiolate ligands (RS)2Fe (NO)2 decompose by a slow and reversible release of NO and a nitrosothiol ... 

Other Applications. TBST is widely used as a thiolate ligand for the s)mthesis of various metal thiolates as exemplified by the formation of Zn(II) thiolate 31 (eq 13) and silver(II) complex 32 (eq 14). ... 

Thiolate ligands have dominated the complexes of the heavier chalcogen donors and continue to be employed in stabilizing the dimthenium unit. Many of the catalytic applications found for diruthenium compounds over the last decade have involved thiolate-bridged species. 

Most widely used methods are based on (i) the competition of protons with the bound metal ions for thiolate ligands, i.e., the pH stability of the metal-thiolate clusters or (ii) the competition with a metal chelator. In the former case the pH stability of the Cd-thiolate clusters is followed by absorption spectroscopy of the CysS-Cd(II) LMCT band at 250 nm. From the apparent p/Ca values the apparent stability constants of the clusters can be derived [103]. The apparent p/sTa values are determined either by taking the pH values of half-maximum absorbance or using a non-linear curve fit of the pH plot [104]. The other method is based on the competition for a single metal ion between the chelator 5F-BAPTA (1,2-bis-(2-amino-5-fluorophenoxy)ethane-A,W,A ,A -tetraacetic acid) and the protein followed by NMR spectroscopy [71]. Although this method was established for the zinc metalloforms of MTs, its applicability to cadmium metalloforms has also been demonstrated [105]. In this case, by analogy with zinc finger proteins a lower affinity for mixed Cys/His coordination of Cd(II) in MTs compared to sole Cys coordination has been shown. 

Schematic diagram of the modification of protection from modification by application of a reversible ligand (agonist or antagonist, ). The reversible binding site specific ligand slows the rate at which the MTS reagent modifies the thiolate group of the introduced cysteine...

As regards other coordination compounds of silver, electrochemical synthesis of metallic (e.g. Ag and Cu) complexes of bidentate thiolates containing nitrogen as an additional donor atom has been described by Garcia-Vasquez etal. [390]. Also Marquez and Anacona [391] have prepared and electrochemically studied sil-ver(I) complex of heptaaza quinquedentate macrocyclic ligand. It has been shown that the reversible one-electron oxidation wave at -1-0.75 V (versus Ag AgBF4) corresponds to the formation of a ligand-radical cation. Other applications of coordination silver compounds in electrochemistry include, for example, a reference electrode for aprotic media based on Ag(I) complex with cryptand 222, proposed by Lewandowski etal. [392]. Potential of this electrode was less sensitive to the impurities and the solvent than the conventional Ag/Ag+ electrode. 

These techniques are applicable only to paramagnetic Mo(V) centers, but the EPR parameters are extremely sensitive to coordination changes at the molybdenum center 17, 64). The molybdenum and ligand hyperfine splittings can provide additional information about the coordination environment of the molybdenum(V) species and the chemical reactions at the molybdenum center. EPR spectra from xanthine oxidase were first reported in 1959 by Bray et al. (65), and Bray and co-workers have continued to develop the application of EPR spectroscopy to molybdenum enzymes 17, 64). In 1966 it was shown (66) that mixing [Mo04] with dithiols produced EPR signals with (g) and (A( Mo)) values similar to those of xanthine oxidase. Only recently, however, have the structures of such thiolate complexes been determined (see Section IV.B.2.b). 39) and P (67) ENDOR spec-... 

Driven in part by interest in potential materials applications,the number of i-block complexes containing ligands with sulfur donors has increased tremendously since the 1980s. The structures of hundreds of such compounds are now known, even though the first crystal structure of a lithium thiolate did not appear until 1985. ... 

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