Electronegativity of the metal cation

The good correlation of catalytic activity and the formation constant of the ammine complex or the electronegativity of the metal cation could... 

As for type (1), Niiyama et al. (42) proposed that protons are generated by dissociation of water and that the equilibrium of the dissociation is a function of the electronegativity of the metal cations. Formation of Bransted acid sites in the aluminum salt of H3PW12O40 as a result of exposure to water vapor at 573 K was confirmed by IR spectra of sorbed pyridine (138). 

These classes are illustrated in Figure 8.15 as the dependency of the valency on the electronegativity of the metal cation. ... 

A correlation between the metal-oxide solubility in molten alkali-metal halides and the electronegativity of the metal cation is shown in our work [360] to consist of two regions alkaline-earth metal-oxides belong to one of them and the second group consists of oxides of transition metals. The dependence of metal-oxide solubilities on the Pauling electronegativities... 

C2 units are also found in solid-state compounds with C-C separations that depend on formal electron count. These are viewed as deprotonated ethyne, ethylene or ethane using a popular solid-state idea the Zintl-Klemm concept. This concept is based on the simple idea that the metals transfer their valence electrons to the non-metal atoms thereby generating filled anion-centered bands at low energy, well separated from empty cation-based bands. Of course, this concept fails when the electronegativities of the metal and non-metal are not very different,... 

The stabilities (/ aswe values) of inner-sphere complexes formed between metal cations and a given ligand increase as the difference in the electronegativities of the metals and the ligand decrease. Explain this statement with examples. 

FIGURE 8.15 Charge vs. critical electronegativity diagram showing five classes of behavior for the zero-charge M[0 2r-J° species of the metal cation In domains 1 and V, the species remain monomeric and solnble. In domain 11 the species condense by olation only, and in domain IV solely by oxolation. Both latter condensation processes may be simnltaneons in domain 111. (From Johvet, J.-R, Metal Oxide Chemistry and Synthesis, John Wiley Sons, Chichester, U.K., 2000, 35. With permission.)... 

As with the dependences discussed above, the correlation of the metal-oxide solubility with the electronegativity by Allred and Rochow consists of two plots characterized by close slopes. The observed shift of the correlation dependences for s - and 3d-elements can be connected with the systematic difference of the calculated effective charge of the metal cations belonging to the mentioned groups. 

The results indicate that Ag/SiOa catalyst is low in the activity for the decomposition of methanol to CO and H2, but that the activity increases as the electronegativity of alkali metal cation decreases. The Ag-CsOH/SiOa catalyst is very active for the decomposition of methanol in the absence of MP. 

It is known that an oxide support can strongly interact with another supported oxide, affecting its reducibility, and that the stability of supported oxides is determined by the similarity of the electronegativities of the two cations. It is interesting to note, in this context, that in activated Sn-Pt/Si02 and Sn-Ru/Si02 catalysts tin is mainly present as metallic Sn° and as metal-tin alloys, while in activated Sn-Pt/AbOB and Sn-Ru/AbOa tin is otherwise stabilized as It is... 

Fig. 6.22 Decomposition temperature for metal tetrahydroalanates and metal tetrahydroborates versus the Pauling electronegativity of the metal atom, which forms the cation. The horizontal line is at 300 K. A...

Because, in general, the soft-acid cations tend to have large electronegativities, it follows that there might be a trend in the standard reduction potentials of the metal cations and their Pauling electronegativities. In fact, there is quite an excellent correlation between the two, as demonstrated by the data in Figure 14.10. 

Closed shell metalloporphyrins such as those having divalent ions (e.g., magnesium or zinc) readily undergo oxidation to radical cations/ These closed shell ionic metalloporphyrins can be considered to be porphyrin dianions, and therefore they are oxidized more readily than are the free porphyrins themselves. The redox potentials of metalloporphyrins increase with increasing electronegativity of the metal ion. Metalloporphyrins with trivalent or tetravalent metal ions are particularly difficult to oxidize because of the high electropositive character of the metal center. 

Fig. 67. Gas sensitivities of 5 wt.% metal oxide loaded-Sn02 elements to 1000 ppm ethanol in air at SOO C as correlated with the electronegativities of loaded metal cations (Matsushima et al. 1989). (Reprinted by permission of the publisher. The Chemical Society of Japaiu)...

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