Compounds of the Main Group Elements

The arrangement of the elements considering their properties as a function of their atomic number established in the Periodic Table permits us to classify them into two large groups The Main Group Elements, i.e. the alkaline, alkaline earth, and post-transition elements, and the Transition Metals. Table 4.1 summarizes selected properties of Main Group Elements. 

The elements of groups 1 and 2 of the Periodic Table form, in accordance with their low number of valence electrons, metallic solids. The stability of element-element covalent interactions inferred from the existence of gaseous diatomic molecules and the interatomic distances within them appears to be rather low being significative only for the lighter alkali metals. 

Data in Table 4.1 also reflect the well known tendency of the most electronegative elements of the second Period to form multiple bonds. 

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Thio- and seleno-compounds of the main group elements — novel inorganic oligomers and polymers. B. Krebs, Angew. Chem., Int. Ed. Engl., 1983, 22,113-134 (252),... 

R. J. Gillespie, Ring, cage, and cluster compounds of the main group elements. Chem. Soc. Rev. 1979, 315. 

CHAPTER 12 Organometallic Compounds of the Main Group Elements... 

Considering the influence of electronic configurations on crystal structures it may be asked, whether certain structure t5rpes are restricted to fluorine compounds of the transition elements. Apart from the structure types distorted by the Jahn-Teller effect such a limitation is not obvious at all. On the contrary quite a number of structure prototypes are represented by compounds of the main group elements. Bonding thus must be similar in both, main group and transition element fluorides, at least as for the factors that influence crystal structmes. 

Contents. Submissions have been grouped into chemically related categories represented by the chapter headings. Because many of the submissions also incorporate syntheses of starting materials, some procedures are located outside of the category in which they would separately belong. For example, there are syntheses of compounds of the main group elements that appear beyond Chapter 1, such as procedures numbered 10.A, 10.C, 26, 27, 48.A, 50.A, 62.A, and 70.A. Similarly, procedures for some mononuclear complexes are located in Chapter 5, see 44. A, 59. A, 62.B, and 62.C.1, while that of a tetrarhenium derivative is located in Chapter 3, see 19.D. 

Essentially similar methods can be employed to prepare non-homoleptic organometallic compounds of the Main Group elements, EXmR etc. Some procedures unique to particular classes of compound are important, for example the mercuration of aromatic hydrocarbons by mercuric acetate ... 

The spectra of many organometallic compounds of the main group elements have been measured but a discussion of these results does not fall within the scope of this review. 

According to the formalism of Akiba11 hypervalent compounds are compounds of the main group elements (sp elements Groups 1, 2, 13-18) those contain a number (N) of formally assignable electrons of more than the octet in a valence shell directly... 

Catalysis in such a mechanism can be attributed to weakening of the peroxidic linkage by formation of an inner-sphere complex with the metal. It could be especially applicable to compounds of the main group elements. Such processes are probably involved in the catalytic decomposition of hydroperoxides by sul-fonium compounds (see later), boron esters, or Se02, e.g.,... 

The most important complexes involving carbon-containing ligands in which carbon is bound to the metal are discussed separately those of carbon monoxide in Chapter 16, organometallic compounds of transition elements, and organometallic compounds of the main group elements in the corresponding chapters. 

This is the second chapter of a two-part review concerned with insertion reactions of transition metal-carbon a-bonded compounds. The first chapter, which appeared in Volume 11 of this series (137), provided a broad introduction to the subject of insertion reactions in general and a detailed treatment of the carbon monoxide insertion and decarbonylation. Presented herein are the insertion and elimination reactions of sulfur dioxide and of a few other unsaturated molecules. The reactions of sulfur dioxide are accorded a complete literature coverage, whereas those of the other inserting species are treated selectively. Metal-carbon a-bonded compounds of the main group elements are discussed only in the context of comparisons with their transition metal analogs. 

Recently, significant progress has been made in the characterization of main group adducts of these carbenes. This chapter will deal only with carbene compounds of the main group elements reported since 1993 and excludes transition metal carbene compounds (such compounds may be found in the article Carbene Complexes). 

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