Crystal field stabilization energy,

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... 

DR. PATEL In the early stages of some of this work, due to calculations on crystal field stabilization energies, it was thought that vanadium(III) and titanium(III) could be very good candidates for an associative mechanism. Now, there has been some work done on these systems, having to do with enthalpies of activation, which seems to substantiate an associative mechanism. 

Table 1.17 Electronic configuration and crystal field stabilization energies for 3d electrons in transition elements. (Ar) = argon core s 2s 2p 3s 3p. ...

Table 1.18 Crystal field stabilization energies for 3d transition elements according to McClure (1957) (1) and Dunitz and Orgel (1957) (2). ...

Ecfs = crystal field stabilization energy. The other column heads are defined as in table 5.12. Data in kJ/mole. 

The cations in these compounds are Fe and/or Fe". In iron oxides, Fe " is always in the high spin (unpaired d electrons) state. As Fe with five d electrons has no crystal field stabilization energy (CFSE see Chap. 6), regardless of whether it is octa-hedrally or tetrahedrally coordinated, there is little preference for one or the other type of site. For Fe , on the other hand, CFSE is higher for octahedral than for tetrahedral coordination, so the octahedral coordination is favoured. 

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-... 

The copper ion is not unique in the first-row transition metal series for exhibiting this diversity of polyhedral environments within a single structure, since Mn2+ (not a Jahn-Teller ion, but one which has no strong crystal-field stabilization energy for highly symmetrical sites) shows a 20 % preference for occupying multiple crystallographic sites. 

Prof. Basolo wants us to go back to steric effects completely. I feel that we have really never abandoned steric effects, and it is rather inconsistent for one of the coproposers of crystal field stabilization energy to be telling us to go back to steric effects. 

Correlations between catalytic activity and a variety of bulk properties of semiconductors have been reported (i) the average band gap of III-V and II-VI semiconductors and activity towards hydrogenation of isopropanol (ii) enthalpy of oxides and their activity towards oxidation of propylene and (iii) number of d-electrons (and crystal field stabilization energy) or 3rf-metal oxides and their activity towards N2O decomposition. The last correlation, due to Dowden (1972), is important since it provides a connection between heterogeneous catalysis and coordination chemistry of transition-metal compounds. A correlation between the catalytic activity of transition-metal sulphides towards hydrodesulphurization of aromatic compounds and the position of the transition metal in the periodic table has been made by Whittingham ... 

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