The f-Block Metals

The lack of steric hindrance in the [(Cp)iLnBu] complex is likely to result in a product containing two (Cp)2Ln units bridged by a ligand system. In fact the product consists of two (Cp)2Ln units bridged by a hydrido ligand. 

The C2g interactions are sketched below. Note that this overlap involves a 6d atomic orbital on the actionoid atom and that the overlap is S type. 

1 (a) Balanced equation. All lanthanoids are very electropositive and reduce water (or protons) to H2 while being 

The ionic radius of Lu is significantly smaller than La because of the incomplete shielding of the 4f electrons of the former. This is also sometimes referred to as lanthanide contraction. 

3 The unusual oxidation states displayed by two of the lanthanoids, +4 for Ce and +2 for Eu (see Exercise 23.1) were exploited in separation procedures because their charge/radius ratios are very different than those of the 

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The block metals are the workhorse elements of the periodic table. Iron and copper helped civilization rise from the Stone Age and are still industrial metals of the greatest importance. Other members of the block include the metals of the new technologies, such as titanium for the aerospace industry and vanadium for catalysts in the petrochemical industry. The precious metals—silver, platinum, and gold—are prized as much for their appearance, rarity, and durability as for their usefulness. Compounds of d-block metals give color to paint, turn sunlight into electricity, serve as powerful oxidizing agents, and form the basis of some cancer treatments. 

In light of these considerations it is surprising that the f-block metal derivatives of this readily accessible ligand have not been explored. In this review we describe some results which begin to rectify this deficiency. 

The elements in the two tan rows containing 14 columns are the ones in which the valence/orbitals are being filled and make up the/block. Consequently, these elements are often referred to as the f-block metals. In most tables, the/block is positioned below the periodic table to save space ... 

Fig. 23.2 Trends in the values of standard enthalpies of atomization (298 K) of the f-block metals values are given in Tables 22.1 and 23.1.

The first part of this paper reviews the synthesis and structures of the f-block metal [8]annulene dianion complexes. For the purpose of this paper, the [8]annulene dianion complexes of the actinides and lanthanides have been classified as bis- or mono-[8]annulene complexes and are further classified by oxidation state of the f-block metal (+3 and +4 for actinides, +2, +3, and +4 for lanthanides). 

Besides the ubiquitous oxidation state Ln +, the higher oxidation state Ln" + is also encountered with some lanthanoids, for example, in the case of the ions Ce" + (f°, orange-yellow), Pr + (f, colorless), Nd" + (f, blue-violet), Tb + (f , colorless), and Dy + (f , orange-yellow) (Table 1). However, all three states Ln + + " + are never encountered for the same element. Thus, the highly important mechanistic steps of oxidative addition and reductive elimination typical for the d-block metals cannot occur with the f-block metals as they would involve M + or transformations, respectively. ... 

Metal carbonyls synthesis, physical properties and structure 899 Table 24.3 Neutral, low-nuclearity (metal carbonyls of the (f-block metals (dec. = decomposes). 

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