Acetylacetonate gold metal

The approach comprises deposition-precipitation (DP) of Au(OH)3 onto the hydroxide surfaces of metal oxide supports from an alkaline solution of HAUCI4 [26] and grafting of organo gold complexes such as dimethyl gold (Ill)acetylacetonate (hereafter denoted as Au acac complex) [27] and Au(PPh3)(N03) [28] either in gas and liquid phase are advantageous in that a variety of metal oxides commercially available in the forms of powder, sphere, honeycomb can be used as supports. 

Gas-phase grafting (GG) is characteristic in that gold can be deposited even on the acidic surfaces, such as activated carbon and on Si02 [27]. The vapor of gold acac complex is adsorbed on the support powder probably through the interaction of electron-rich oxygen atoms in acetylacetonate and then calcined in air to decompose it into metallic gold particles. 

The propensity of transition metal salts such as silver trifluoroacetate (AgTFA), copper acetylacetonate (CuACAC), and gold trichloride (AuCb) to induce molecular cationization is illustrated in Figure 42.19, for the polymer antioxydant Irganox 1010 (Ciba Specialty Chemicals Corporation) and for PS oligomers [304]. In the case of AgTFA, cluster ions and larger adduct ions of the type (M-i-Ag )+ are also visible in the mass spectra. This observation indicates that the silver atoms form clusters on the sample surface. 

Cationic chelates are formed, for instance, when the coordination number is less than double the charge of a central atom, using didentate reagents. Tin(IV) bis(hyd-roxyquinolinate), gold(III) bis(dithizonate), or boron (III) bis(acetylacetonate) are examples of such metal chelates. Another reason for the formation of cationic chelates is steric hindrance as in the cases of alumin -urn bis(2-methyl-8-hydroxiquinolinate), or cobalt(III) bis(dimethylglyoximate) (23,24). 

Olefin-metal complexes are frequently labile, especially those of copper, silver and gold, and treatment of most olefin-metal complexes with ligands such as tertiary phosphines results in the displacement of the olefin. In the square-planar acetylacetonate complex (acac)Rh(C2H4)2 the ethylenes readily exchange with free ethylene - as is also found in the square-planar platinum-olefin complexes [17]. In these planar molecules exchange of olefins may involve olefin attack on the exposed metal atom, via a five-co-ordinated intermediate [65, 66]. 

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