Redox ligands

In general, the introduction of spatially hindered phenols into coordination compounds may produce stable free-radical forms [138b—140]. A series of metal complexes with redox ligands, containing derivatives of 2,6-di-t-butylphenols n- or a-connected, or vicinal fragments in the coordination environment of the central metal atom, were synthesized in this way 7i-aryl [141], Tt-cr-allyl [142] compounds, nitrile complexes [143], metal glioximates [144], salicylaldiminates [145,146], por-phyrines [147-149], and phthalocyanines [150,151],... 

Today research does no longer focus on the dendrimer itself but on the multiplication of functional components attached to a dendritic skeleton and new materials with specific properties (redox, ligand, and liquid crystalline properties, biochemical activity. ..) are anticipated. [9] Industry has also shown increasing interest in functional cascade molecules for applications in diverse areas such as medical engineering, agrochemistry, and the development of photocopier toner additives. Concrete applications include nanoscale catalysts [2a],... 

Syntheses of MPCs with metal cores other than An have seen many advances over the years and applications involving these particles have increased as a result. Less is known about their structures but the range of core sizes obtained is analogous to that of An MPCs, that is, a range from molecule-like particles to larger ones whose ET properties resemble that of the bulk metal. Similar to An MPCs, MPCs of other core metals have highly modifiable surfaces, which can be functionalized with redox ligands or biomolecules to suit a specific application. A discussion of Pd MPCs is followed by another on Pt MPCs and then on to less common core metal MPCs. 

Figure A2.4.13. Potential energy of a redox system as a fiinction of ligand-metal separation. From [7].

In our simple model, the expression in A2.4.135 corresponds to the activation energy for a redox process in which only the interaction between the central ion and the ligands in the primary solvation shell is considered, and this only in the fonn of the totally synnnetrical vibration. In reality, the rate of the electron transfer reaction is also infiuenced by the motion of molecules in the outer solvation shell, as well as by other... 

When the water ligands around a cation are replaced by other ligands which are more strongly attached, the redox potential can change dramatically, for example for the cobalt(II)-cobalt(III) system we have... 

Other important effects of ligand and pH changes on redox potentials will be given under the appropriate element. 

The most important types of reactions are precipitation reactions, acid-base reactions, metal-ligand complexation reactions, and redox reactions. In a precipitation reaction two or more soluble species combine to produce an insoluble product called a precipitate. The equilibrium properties of a precipitation reaction are described by a solubility product. 

The advantages of titanium complexes over other metallic complexes is high selectivity, which can be readily adjusted by proper selection of ligands. Moreover, they are relative iaert to redox processes. The most common synthesis of chiral titanium complexes iavolves displacement of chloride or alkoxide groups on titanium with a chiral ligand, L ... 

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