D block elements

Iron is notable for the range of electronic spin states to which it gives rise. The values of S which are found include every integral and half-integral value from 0 to i.e. every value possible for a d-block element (Table 25.4). 

FIGURE 4. Medium-long form table showing highest and most common oxidation states of the d-block elements. Only two of these 30 ions, Ag+1 and Au+3, (shown in bold-face) show anomalous electronic configurations with respect to other ions in the same groups. 

FIGURE 1.38 The seven /-orbitals of a shell (with n = 3) have a very complex appearance. Their detailed form will not be used again in this text. However, their existence is important for understanding the periodic table, the presence of the lanthanoids and actinoids, and the properties of the later d-block elements. A darker color denotes a positive lobe, a lighter color a negative lobe. 

All d-block elements are metals (Fig. 1.63). Their properties are transitional between the s- and the p-block elements, which (with the exception of the members of Group 12) accounts for their alternative name, the transition metals. Because transition metals in the same period differ mainly in the number of /-electrons, and these electrons are in inner shells, their properties are very similar. 

All d-block elements are metals with properties between those ofs-block and p-block metals. Many d-block elements form cations in more than one oxidation state. 

Because the metallic radii of the d-block elements are all similar, they can form an extensive range of alloys with one another with little distortion of the original crystal structure. An example is the copper-zinc alloy used for some copper coins. Because zinc atoms are nearly the same size as copper atoms and have simi-... 

Ammonia is very soluble in water because the NH3 molecules can form hydrogen bonds to H20 molecules. Ammonia is a weak Bronsted base in water it is also a reasonably strong Lewis base, particularly toward d-block elements. For example, it reacts with Cu2+(aq) ions to give a deep-blue complex (Fig. 15.4) ... 

We begin this chapter by summarizing the major periodic trends exhibited by the t/block elements and their compounds. Then we describe some of the properties and key reactions of selected elements. The d-block metals form a wide variety of complexes and, in the second half of the chapter, we describe their structures and the two principal theories of their bonding. We end the chapter by examining the contribution of d-block elements to some important modern materials. 

The incompletely filled d-subshell is responsible for the wide range of colors shown by compounds of the d-block elements. Furthermore, many d-metal compounds are paramagnetic (see Box 3.2). One of the challenges that we face in this chapter is to build a model of bonding that accounts for color and magnetism in a unified way. First, though, we consider the physical and chemical properties of the elements themselves. 

The shapes of the d-orbitals affect the properties of the d-block elements in two ways (see Fig. 1.37) ... 

FIGURE 16.4 The atomic radii of the d-block elements (in picometers). Notice the similarity of all the values and, in particular, the close similarity between the second and the third rows as a result of the lanthanide contraction. 

The range of oxidation states of a d-block element increases toward the center of the block. Compounds in which the d-block element has a high oxidation state tend to be oxidizing those in which it has a low oxidation state tend to be reducing. The acidic character of oxides increases with the oxidation state of the element. 

Although the physical properties of the d-block elements are similar, the chemical properties of these elements are so diverse that it is impossible to summarize them fully. We can, however, observe some of the major trends in properties within the d block by considering the properties of certain representative elements, particularly those in the first row of the block. 

TABLE 16.1 Properties of the d-Block Elements Scandium Through Nickel... 

The Period 4 d-block elements titanium through nickel are obtained chemically... 

Many of the d-block elements form characteristically colored solutions in water. For example, although solid copper(II) chloride is brown and copper(II) bromide is black, their aqueous solutions are both light blue. The blue color is due to the hydrated copper(II) ions, [Cu(H20)fJ2+, that form when the solids dissolve. As the formula suggests, these hydrated ions have a specific composition they also have definite shapes and properties. They can be regarded as the outcome of a reaction in which the water molecules act as Lewis bases (electron pair donors, Section 10.2) and the Cu2+ ion acts as a Lewis acid (an electron pair acceptor). This type of Lewis acid-base reaction is characteristic of many cations of d-block elements. 

Explain trends in chemical and physical properties among the d-block elements (Sections 16.1 and 16.2). 

The elements that can form cations relatively easily are metals. All metals have similar properties, in part because their outermost s electrons are relatively easy to remove. All elements in the s block have ns or n s valence configurations. The d-block elements have one or two n S electrons and various numbers of (n - 1) d electrons. Examples are titanium (4 S 3 d ) and silver (5 Ad ). Elements in the f block have two S electrons and a... 

A common feature of catalysts based on 4 and 5f block elements is that of being able to polymerize both butadiene and isoprene to highly cistactic polymers, independently of the ligands involved. Butadiene, in particular, can reach a cistacticity as high as 99% with uranium based catalysts (3) and cistacticity of > 98% with neodymium based catalysts (4). This high tacticity does not change with the ligand nature (Fig. 1) in contrast to conventional catalysts based on 3-d block elements. A second feature of f-block catalysts is that the cis content of polymer is scarcely... 

Many compounds of p- and d-block elements containing El Cl or El Br bonds react with 1 under insertion into these bonds. In some cases, the formed insertion products are stable under ordinary conditions. In other cases, the insertion products undergo further sometimes rather complicated rearrangement and elimination reactions such situations are described in Chapter IV. D. 

Certain metal alkyl compounds from p- and d-block elements react under very mild conditions with 1 under insertion into the element-carbon bond. Some examples are shown in Scheme 9. 

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