Metal thiolates application

Aryl halides containing less reactive halogen can also be converted into sulfides by thiols if heavy-metal (lead, zinc, mercury) thiols are used at 225-230° 1-naphthyl, 2-naphthyl sulfide,301 1- and 2-naphthyl phenyl sulfide,302 and 1-and 2-naphthyl o-, m-, and p-tolyl sulfide303 have been obtained in this way. When the heavy-metal thiolates are too stable and do not react with aryl bromides even at 240°, the aryl sulfides can nevertheless often be prepared by a generally applicable reaction of aryl iodides with sodium thiolates under the influence of copper as catalyst.304... 

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). ... 

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. 

Heterocycles treated in this section belong to several structure types. The metal atoms in compounds under discussion can exist not only in the tetravalent but also in the carbenoid divalent state and the heterocycles differ not only in the nature and number of metal atoms but also in the nature of ring bonds of the latter. Thus, besides conventional organometallic compounds having only M—C bonds there are heterocycles with M—M bonds and those with C—M—X or X—M—Y fragments (X and Y—common heteroatoms like O, S, N). The last type is the most numerous and important group of five-membered Ge-, Sn- and Pb-heterocycles in which the metals are involved in M—X and M— Y bonds similar to those in respective metal alkoxides, thiolates and amides. This feature not only affects the structural parameters of these compounds but determines their chemical properties, synthetic routes and applications. 

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. 

DeVries et al.224 demonstrated experimentally that polar singularities form when a curved surface is coated with ordered monolayers (hairy-ball-theorem). The thiolates bound at the polar positions exchange faster than those in the bulk monolayer, thus allowing introduction of two—and only two—functional groups at the poles of a nanoparticle.224 This was the first example of divalent metal nanoparticles. This discovery opens up the path to new applications in the field of materials chemistry, and supramolecular chemistry, as stressed by Perepichka and Rosei.225 Undoubtedly, the regiochemical stability of these disubstituted nanoparticles and the chemical yield of their functionalization should be the subject of future studies. 

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-... 

The kinetics of the deposition of In20i films have not been investigated by many groups, since most of them concentrate on the physical properties and possible applications. The published results are listed in Table 3-8. In addition, there are only two remarks about decomposition pathways. Maruyama andTabata [111] state that indium acetate needs no oxygen as reactant to form indium oxide, i.e., some of the metal-oxygen bonds are not broken during the deposition. Also, as proposed by Nomura and coworkers [122], the butylindium thiolate decomposes via formation of indium sulfides ... 

Thiolato derivatives of main-group metals provide an interesting contrast to those of the transition metals, since despite the industrial application of compounds such as organotin sulfides, much remains to be done in the study of the chemistry of these interesting compounds. Methods for the preparation of organotin thiolates and selenolates have been reviewed, as have their physical and chemical properties. The preparation of tris(benzenethiolato)-indium by the reaction of InClj with NaSCgHj in methanol has recently been described, as have the properties of this compound. ... 

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