- Oxidative Mechanochemistry: Direct, Room-Temperature, Solvent-Free Conversion of Palladium and Gold Metals into Soluble Salts and Coordination Complexes
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Noble metals are valued, critical elements whose chemical activation or recycling is challenging, and traditionally requires high temperatures, strong acids or bases, or aggressive complexation agents. By using elementary palladium and gold, demonstrated here is the use of mechanochemistry for noble-metal activation and recycling by mild, clean, solvent-free, and room-temperature chemistry. The process leads to direct, efficient, one-pot conversion of the metals, including spent catalysts, into either simple water-soluble salts or metal–organic catalysts.
- Do, Jean-Louis,Tan, Davin,Fri??i?, Tomislav
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supporting information
p. 2667 - 2671
(2018/02/06)
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- Synthesis, structural characterization and in vitro cytotoxicity of new Au(III) and Au(I) complexes with thioamides
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The reactions of tetrachloroauric(III) acid (HAuCl4) with the thioamides; 2-mercapto-benzothiazole (mbztH) and 5-ethoxy-2-mercapto- benzimidazole (EtmbzimH) lead to the desulfuration of the ligands and the formation of the ionic complexes {[AuCl4]-[bztH 2]+} (1), and {[AuCl4]-[EtbzimH 2]+(H2O)} (2) (where bztH2 + and EtbzimH2+ are the desulfurated cations of the starting ligands). The reaction of HAuCl4 with 2-mercapto-nicotinic acid (mnaH2), however results in the formation of 2-sulfonate-nicotininc acid (C6H5NO5S) (3) with the simultaneous oxidation of the sulfur atom. On the other hand, the reactions of the gold(I) complex [Au(tpp)Cl] (4) (tpp = triphenylphosphine (Ph3P)) with the thioamides; 2-mercapto-thiazolidine (mtzdH), 2-mercapto-benzothiazole (mbztH) and 5-chloro-2-mercapto-benzothiazole (ClmbztH) in the presence of potassium hydroxide resulted in the formation of the gold(I) complexes of formulae [Au(tpp)(mtzd)] (5), [Au(tpp)(mbzt)] (6) and [Au(tpp)(Clmbzt)] (7) without ligand desulfuration. All complexes have been characterized by elemental analysis, FT-IR, far-FT-IR,1H-NMR, spectroscopic techniques and X-Ray crystallography. The electrochemical behavior of 1, 2 and 4-7 complexes and the ligands EtmbzimH, mbztH and mnaH2 was also studied in acetonitrile and DMF using cyclic voltammetry. The results are in support of a mechanism of desulfuration of the ligands by Au(III), involving a first oxidation of S to -SO3-, followed by a C-S bond cleavage. This is also supported by PM6 calculations of bond dissociation energies of the various compounds involved. Complexes 1, 2 and 4-7 were tested for in vitro cytotoxicity against leiomyosarcoma cells and the results are discussed in relation with the geometry of the complexes and compared with those of cisplatin and other metals. Complexes 1 and 5 showed higher activity than that of cisplatin, while HAuCl4 was inactive against sarcoma cells.
- Kouroulis,Hadjikakou,Kourkoumelis,Kubicki,Male,Hursthouse,Skoulika,Metsios,Tyurin,Dolganov,Milaeva,Hadjiliadis
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p. 10446 - 10456
(2010/04/04)
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