Transition metal plots

The volume per mole of atoms of some fourth-row elements (in the solid state) are as follows K, 45.3 Ca, 25.9 Sc, 18.0 Br, 23.5 and Kr, 32.2 ml/mole of atoms. Calculate the atomic volumes (volume per mole of atoms) for each of the fourth-row transition metals. Plot these atomic volumes and those of the elements given above against atomic numbers. 

Figure 2.16. Calculated dissociative nitrogen ( ), carbon monoxide ( ), and oxygen ( ) chemisorption energies over different 3d transition metals plotted as a function of the center of the transition metal rf-bands. A more negative adsorption energy indicates a stronger adsorbate-metal bond. Reproduced from [32].

FIGURE 8.8 Calculated oxygen adsorption energies on the most close-packed surface of the 4d transition metals plotted against upper band-edge descriptor. The descriptor accounts for the position of the upper edge of the d-band and hence the position of the antibonding state. Adapted from Vojvodic et al. (2013). 

Field Stabilization Energies, or LFSE s. The variation in LFSE across the transition-metal series is shown graphically in Fig. 8-6. It is no accident, of course, that the plots intercept the abscissa for d, d and ions, for that is how the LFSE is defined. Ions with all other d configurations are more stable than the d, d or d ions, at least so far as this one aspect is concerned. For the high-spin cases, we note a characteristic double-hump trace and note that we expect particular stability conferred upon d and d octahedral ions. For the low-spin series, we observe a particularly stable arrangement for ions. More will be said about these systems in the next chapter. 

Sabatier s Principle is illustrated in Fig. 6.40 where the ammonia rate is plotted for similar conditions versus the type of transition metals supported on graphite. The theory outlined so far readily explains the observed trends metals to the left of the periodic table are perfectly capable of dissociating N2 but the resulting N atoms will be bound very strongly and are therefore less reactive. The metals to the right are unable to dissociate the N2 molecule. This leads to an optimum for metals such as Fe, Ru, and Os. This type of plot is common in catalysis and is usually referred to as a volcano plot. 

Besides supported (transition) metal catalysts, structure sensitivity can also be observed with bare (oxidic) support materials, too. In 2003, Hinrichsen et al. [39] investigated methanol synthesis at 30 bar and 300 °C over differently prepared zinc oxides, namely by precipitation, coprecipitation with alumina, and thermolysis of zinc siloxide precursor. Particle sizes, as determined by N2 physisorpt-ion and XRD, varied from 261 nm for a commercial material to 7.0 nm for the thermolytically obtained material. Plotting the areal rates against BET surface areas (Figure 3) reveals enhanced activity for the low surface area zinc... 

Logadottir A, Rod TH, N0rskov JK, Hammer B, Dahl S, Jacobsen CJH. 2001. The Br0nsted-Evans-Polanyi relation and the volcano plot for ammonia synthesis over transition metal catalysts. J Catal 197 229. 

Figure 9-1. Schematic plot of the (4s + 3dz2) and (4s - 3dz2) orbitals of a third-row transition-metal involved in a M-X bond.

In general, there are insufficient data available for quantitative estimates to be made of the hardnesses of intermetallic compounds. However, in some cases trends can be verified. Figure 8.11 illustrates one of these. It indicates that hardnesses and heats of formation tend to be related. In this case for a set of transition metal aluminides. The correlation in this case might have been improved if the heats per molecular volume couls have been plotted, but thr molecular volumes were not available. Nevertheless, the correlation is moderately good indicating that hardness and chemical bond strengths are related as in other compounds. 

Fig. 13 a Plot of P 2p3/2 BE vs. difference in electronegativity between P and M in several transition-metal monophosphides MP. This work filled circle [52] open circle, b Plot of P charge (interpolated from BE values) vs. difference in electronegativity. Reprinted with permission from [58], Copyright the American Chemical Society... 

The most striking feature of Figs. 7 and 8, particularly as compared with the hydride plot, is the plunge downfield of the resultant shielding, following the paramagnetic term, across the row of the central atom for the typical elements, and also for the early transition metals (Fig. 8), with ready circulation of fluorine 2p electrons into empty t g orbitals in the complexes. Fluorine is h hly shielded however in the d molecules and ions, and this was discussed in Section III, B as a possible Cornwell effect (62). 

---