Gold complexes hydrolysis

In their subsequent report, Raymond et al. used the encapsulated gold complex, Au-Ga4L5, in combination with enzymes, esterases, or lipases in a one-pot tandem reaction sequence. Enzymatic ester/imide hydrolysis of allenic ester or amide results in an intermediate [27], which subsequently undergoes... 

Hydrolysis of gold(I) in aqueous acetonitrile solutions gives Au(OH)3 and the gold(I) hydroxo complex [Au(OH)(MeCN)], which has not been isolated in the solid state.271 The complex [Au2(/i-OI I)(PMcx3)2]BF4 has been isolated from the reaction of [AuCl(PMes3)] with AgBF4 and NaOH.2714... 

The use of a lipophilic zinc(II) macrocycle complex, 1-hexadecyl-1,4,7,10-tetraazacyclododecane, to catalyze hydrolysis of lipophilic esters, both phosphate and carboxy (425), links this Section to the previous Section. Here, and in studies of the catalysis of hydrolysis of 4-nitrophenyl acetate by the Zn2+ and Co2+ complexes of tris(4,5-di-n-propyl-2 -imidazolyl)phosphine (426) and of a phosphate triester, a phos-phonate diester, and O-isopropyl methylfluorophosphonate (Sarin) by [Cu(A(A(A/,-trimethyl-A/,-tetradecylethylenediamine)l (427), various micellar effects have been brought into play. Catalysis of carboxylic ester hydrolysis is more effectively catalyzed by A"-methylimidazole-functionalized gold nanoparticles than by micellar catalysis (428). Other reports on mechanisms of metal-assisted carboxy ester hydrolyses deal with copper(II) (429), zinc(II) (430,431), and palladium(II) (432). 

Gold(III) organometallics are isoelectronic with cisplatin-like Ptn complexes. For example, complex 10 hydrolyses in water [123] and has shown activity in human tumour xenograft models [124]. However, its mechanism of action is different from that of cisplatin [124,125]. The role of hydrolysis as an activation step for this class of compounds is not yet clear. 

Both are dimers in the solid and in the vapor. They dissolve in water, undergoing hydrolysis, but in HX the ions AuXi are formed. Gold(III) chloride is a powerful oxidant, being reduced to Au it will, for example, oxidize ruthenium complexes in aqueous solution to Ru04. 

Gold(III), like Ptn, displays predominantly square coordination. Although there is little evidence for any persisting 5-coordinate complexes, there is no doubt that, as with Pt11 species, substitution reactions proceed via 5-coordinate intermediates. There is no evidence for a simple aqua ion, [Au(H20)4]3+, but mixed chloro-aqua and chloro-hydroxo complexes are formed by hydrolysis of [AuCI4]" Distorted octahedral coordination occurs rarely, [Au(en)2Cl2]+ being an example. 

CE separations of inorganic anions are almost always carried out at an alkaline pH to ensure that the analytes will be in the ionic rather than the molecular form. However, a flow modifier must generally be used to reverse the direction of EOF. Thornton and Fritz found that excellent separations of anions are possible at pH values as low as 2.0 (HCl) or 1.8 with perchloric acid [5]. Special attention was paid to the anionic chloro complexes of gold (III) and the platinum group elements, which are more resistant to hydrolysis in more acidic solutions. By working at lower pH values, the capillary silanol groups are largely un-ionized and consequently the EOF is minimal. 

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