Complexes crystal field stabilization energy

Tables 2.4.3 and 2.4.5 show that, for d , d and d complexes, crystal field stabilization energies (AE ) are negative or zero, which means that their reactions are fast regardless of the mechanism. In fact, these complexes are labile. On the other hand, d octahedral complexes as well as d, d and d complexes have positive AE, which indicates slow reactions. Indeed, complexes of this type are inert. In addition, d and d and d complexes ( outer-orbital complexes, i.e., complexes of a weak crystal field) are labile, as expected. Their AE are negative or zero (E is lowered) and therefore the reactions are fast regardless of the mechanism).

Another factor that affects trends in the stability constants of complexes formed by a series of metal ions is the crystal field stabilization energy. As was shown in Chapter 17, the aqua complexes for +2 ions of first-row transition metals reflect this effect by giving higher heats of hydration than would be expected on the basis of sizes and charges of the ions. Crystal field stabilization, as discussed in Section 17.4, would also lead to increased stability for complexes containing ligands other than water. It is a pervasive factor in the stability of many types of complexes. Because ligands that form tt bonds... 

The M-ferrihydrite coprecipitate contains M-O/OH-Fe and M-O/OH-M as well as Fe-O/OH-Fe linkages. The transition elements stabilize ferrihydrite in the order, Mn < Ni < Co < Cu < Zn (Cornell, 1988 Giovanoli Cornell, 1992). This order does not correspond with that of the electronegativities or the crystal field stabilization energies (CFSE) of these elements, nor does it match the order of binding constants for the M-surface complexes. If Zn is omitted from the series, however, there is a reasonable cor-... 

In general, the thermal stability of metal-containing polymer systems is relatively enchanced compared to that of the bulk polymer. Various factors including size and concentration of the metal ions, and crystal field stabilization energy of the anchored metal complexes influence the stability to different extents. 

Inai et al. [483] suggested that an activated complex with a pentagonal bipyramid-type structure was formed in the transition state in the Volmer— Heyrovksy-type mechanism for chlorine evolution at Ru02. A theoretical activation energy for this reaction was calculated by using the difference in the crystal field stabilization energy between the initial and transition... 

Variable coordination numbers. The coordinating stabilization energy (about 4.18 kJ-mol ) of lanthanide ions is much smaller than the crystal field stabilization energy of transition metals (typically >418 kJ moP ). Therefore, the coordinating bonds of lanthanide complexes are not directional and the coordination number varies from 3 to 12. 

Assuming a pairing energy of 16,000 cm calculate the crystal field stabilization energies (in kj mol ) and spin-only magnetic moments of the following complexes ... 

TABLE 8.5 Electron Configurations and Crystal Field Stabilization Energies for High- and Low-Spin Octahedral Complexes... 

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