Ammines 208 Subject

Ruthenium(III), d5 Ru111 is often associated with classical-type ligands, e.g. ammine, water, halides. They are octahedral low spin t2/ species with one unpaired electron and generally sub-stitutionally inert. The electronic structure of polynuclear carboxylates and mixed valence Ru" 1" complexes of the type [Ru(NH3)5]2L5+ has been the subject of much interest particularly with respect to the degree of unpaired electron delocalization within these molecules. 

X-Ray diffraction has been used to identify the locations of noble metal ions in faujasites after subjecting the amminated precursors to a variety of calcination conditions (141-148). These ions remain in the supercages after partial oxidation of the ammine ligands at low temperature, but they migrate into sodalite cages after calcination at high temperature. This has been shown in detail for Pt and Pd ions in zeolite Y. 

All ligands receive a separate subject entry, e.g., 2,4-Pentanedione, iron complex. The headings Ammines, Carbonyl Complexes, Hydride complexes, and Nitrosyl complexes are used for the NH, CO, H, and NO ligands. 

Previously reported work demonstrated that substituents can be used to tune the energies of excited states responsible for the emission spectra of certain group VIII metal complexes (1) and to modify significantly the absorption spectra of complexes displaying metal-to-ligand charge transfer (MLCT) bands (2). In this presentation, we summarize some recent attempts to use ligand substituents in our studies of transition metal complex photochemical reaction mechanisms. The particular subjects of interest are the metal ammine complexes M(NH3)5L where M is Rh(III) or Ru(II) and L is a meta- or para-substituted pyridine. 

The catalytic activity of co-ordination compounds in oxidations continues to be examined and, together with the Faraday Society Discussion, other aspects of this area of investigation have been the subject of recent reviews. Redox reactions involving bipyridyl and u-phenanthroline complexes of transition metals have been discussed and catalytic oxidations of complexes of manganese, cobalt, copper, and palladium have also been surveyed. Reviews are also available of ruthenium ammine chemistry, and redox reactions involving molybdenum complexes, together with an account of catalase and peroxidase reactivity of copper(ii) complexes. ... 

Apart from using ammine complexes as a probe for adsorption mechanisms, there is a need to develop treatment procedures for ammonia-containing metal wastes. Ammonia-containing metal wastes are encountered in, for example, mining by-products, which may be subject to ammoniacal leaching either directly or after treatment [51,58,59]. Leather tannery effluent also contains high levels of Cr(III), often in the presence of ammonia, the pollutant that causes the most difficulty in Cr(IIl) effluent treatment [8]. 

The first stage in this process is likely to be an Anderson rearrangement, followed by deprotonation of the coordinated ammine. The complex [NH4]2[TcF5l has been shownSO to be subject to a similar transformation. 

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