Ligand removal

EXAFS results and fitting parameters compared between two precursors after ligand removal are displayed in Table 1. 

Table 1 Coordination number (N) and bond distance (R) of cluster core of crystalline A determined by XRD [3] and EXAFS data of PtRu/MgO prepared from cluster A and acac precursors after ligand removal...

The literature of metal-support interactions includes httle about the possible chemical bonding of metal clusters or particles to supports. Supported molecular metal clusters with carbonyl ligands removed have afforded opportunities to understand the metal-support interface in some detail, and the results provide insights into the bonding of clusters to supports that appear to be generalizable beyond the small clusters to the larger particles of conventional supported metal catalysts [6]. 

AfGnity capture-MS Immobilized on beads Incubated with immobilized target Bead-bound target mixed with potential ligands unbound ligands removed by washing bound ligands eluted and identified by ES-ME/MS (Kelly et al., 1996)... 

Fig. 1. The surface sites of the Au-core of Aujj are shown schematically, with the ligands removed. The light grey circles represent the uncoordinated surface atoms, the dark grey circles represent PPhj-coordinated surface atoms, and the black circles represent the Cl-coordinated surface atoms. The 13 atoms of the two inner shells are not visible...

Accordingly, cluster formation reactions can be (a) (I) - (II) with L/M increase (usually by ligand addition) or (b) (III) -+ (II) with L/M decrease (by ligand removal or metal addition). The Zn2+/ SPh and Cu+/ SPh systems exemplify both directions of formation of molecular cages ... 

Calcination required for ligand removal, complex reaction, difficult to control not required... 

Wienold et al. (2003) XAS, TGA Ammonium heptamolybdate Phase formation ligand removal, sub-oxides + + + Propene oxidation, oxidation and reduction of oxide... 

The literature was reviewed to describe the newest efforts to synthesize and characterize supported polynuclear metal complexes as adsorbents and catalysts. This review includes our attempts to model the equilibrium structures and properties of the metal complexes, using simple quantum mechanics, as a means to understand better the interactions between the surface and the metal complexes. Special attention is directed towards the characterization of the supported metal complexes before and after ligand removal. We compare these modeling results with observations in the literature so as to understand better the fundamental processes that govern the interactions between the metal complexes and the surfaces. With this enhanced understanding of these governing factors, it should be easier to prepare oxide solids decorated with metal complexes having the desired physico-chemical properties. 

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