Third transition series

These elements formed Group IIB of Mendeleef s original periodic table. As we have seen in Chapter 13, zinc does not show very marked transition-metaf characteristics. The other two elements in this group, cadmium and mercury, lie at the ends of the second and third transition series (Y-Cd, La-Hg) and, although they resemble zinc in some respects in showing a predominantly - - 2 oxidation state, they also show rather more transition-metal characteristics. Additionally, mercury has characteristics, some of which relate it quite closely to its immediate predecessors in the third transition series, platinum and gold, and some of which are decidedly peculiar to mercury. 

As a general rule, elements in the second and third transition series have similar chemical properties. In contrast, the properties of the first member of the series are often different. This pattern of behavior is seen in Group 7 (VIIB). The properties of rhenium and technetium differ considerably from those of manganese. 

For the heavier congenors, tungsten in the group oxidation state is much more stable to reduction, and it is apparently the last element in the third transition series in which all the 5d electrons participate in metal bonding. 

The electronic spectra of the hexafluoro complexes of the second and third transition series. G. C. Allen and K. D. Warren, Struct. Bonding (Berlin), 1974,19,105-165 (94). 

Allen GC, Warren KD (1974) The Electronic Spectra of the Hexafluoro Complexes of the Second and Third Transition Series. 19 105-165 Alonso JA, Baibas LC (1993) Hardness of Metallic Clusters. 80 229-258 Alonso JA, Baibas LC (1987) Simple Density Functional Theory of the Electronegativity and Other Related Properties of Atoms and Ions. 66 41-78 Andersson LA, Dawson JH (1991) EXAFS Spectroscopy of Heme-Containing Oxygenases and Peroxidases. 74 1-40 Antanaitis BC, see Doi K (1988) 70 1-26... 

Fig. 5. The change in stability constant for different ligands with metals in the second and third transition series...

SS). Data for the metals of group VIII and for rhenium in group VIIA are given in Fig. 1, which is divided into three fields separating the metals of the first, second, and third transition series. The specific activity is defined as the activity per unit surface area of metal. Metal surface areas required for the determination of specific activities are derived from measurements... 

Allen,G.C., Warren,K.D. The Electronic Spectra of the Hexafluoro Complexes of the Second and Third Transition Series. Vol. 19, pp. 105—165. 

The Electronic Spectra of the Hexafluoro Complexes of the Second and Third Transition Series... 

The general procedure for constructing Lewis-like diagrams for transition-metal species can best be illustrated by representative examples. From Table 4.1 one can recognize that the first transition series (Sc-Zn) includes a disproportionate number of exceptional cases compared with later series, and illustrative examples will therefore be drawn primarily from the third transition series (La-Hg). (The somewhat anomalous behavior of the first transition series and general vertical trends in the d-block elements will be discussed in Section 4.10.)... 

Let us begin by considering the duodectet-rule-conforming metal hydrides of the third transition series (W-Au), which have the Lewis-like diagrams... 

Table 4.4. Bond lengths 7 mh and angles hmh of saturated metal hydrides MH of the third transition series (see Fig. 4.7)...

Table 4.5. The NBO descriptors of group 6-11 MH metal hydrides of the third transition series, showing the percentage accuracy (%fy) of the Lewis-like description (valence shell and total), metal hybrid (Iim), percentage polarization toward M (100cm2), and occupancy of bonding ctmh NBOs (see Fig. 4.8)...

Table 4.6. Geometries and NBO descriptors 0/MH2 and MH3 metal hydrides of the third transition series of various spin multiplicities (IS + I), illustrating the correlations of metal charge (Qu) with metal hybrid d character (%d, taken as the average of a and 3 hybrids for open-shell species), bond length (Ruw) and angle (9hmh)> and average absolute deviation (Dev. = average %mh — 90" ), from idealized covalent geometry...

Table 4.8. Bond lengths Rwc and 7 mh) and angles ( cmh and hmh) of saturated metal methylhydrides MH Mc of the third transition series...

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