Organogermanium

The field of organogermanium chemistry is becoming increasingly important. Gertain germanium compounds have a low mammalian toxicity, but a marked activity against certain bacteria, which makes them useful as chemotherapeutic agents. 

Organogermanium Compounds. The field of organogermanium chemistry has drawn widespread interest for many years. 

E. Rijkens, Organogermanium Compounds, Germanium Research Committee, Utrecht, the Netherlands, 1960. 

E. Rijkens and G. J. M. Van der Kerk, Investigations in the Field of Organogermanium Chemisty, Germanium Research Committee, Utrecht, the Netherlands, 1964. 

Chapter 10, section 3 Organogermanium-transition metal complexes, pp. 672-688. 

The first examples of optically active organogermanium compounds [see Ref. 2)] in which the metal atom is again the only chiral center were published in 1963, by Eaborn 3 and by Brook4>. They prepared optically pure (+)-ethyl- and (-)-methyl- 1-naphthylphenylgermanium hydrides, using Sommer s resolution method u. 

Organogermanium compounds resemble their organosilicon analogues in their reactivity in crosscoupling reactions, and require nucleophilic activation (Section 9.6.3.2 2)... 

In organogermanium dithiophosphinates the ligand is monodentate, whereas in heavier metal compounds M -S secondary bonds may result in supramolecular self-assembly. Examples are monomeric Ph3GeS(S)PR2 (R = Me, Ph),165 and Me2Sn(S2PR2)2 (R = Me,166 Et167), supramolecular chain-like... 

In spite of the interesting results obtained for organometallic dithiophos-phates, similar studies with diselenophosphates have not been performed for comparison. Only recently some organogermanium, -tin, and -lead derivatives of the type Ph3MSe(Se)P(OR)2 (M = Ge, Sn, Pb R = Et, Pr, Pr ), containing monodentate ligands have been reported.446... 

The geometric structure of organogermanium betaine 24 is similar, as a whole, to that of the corresponding silicon analog 20o. The main distinctions are an additional shortening of the PC bond lengths and a further... 

In contrast to silicon, germanium has a well-established though limited chemistry of inorganic compounds in the +11 state which are of reasonable thermal stability though usually air-sensitive. Divalent organogermanium(II) species known at present fall into three groups ... 

Recent volumes of the Gmelin Handbook. Organogermanium—Part 5, Ge—O Compounds and Organotin, Vol.20, Springer-Verlag, Berlin, 1993. 

H. Sakurai and A. Sekiguchi, in Frontiers of Organogermanium, -Jin, and -Lead Chemistry (Eds. E. Lukevics and L. Ignatovich), Latvian Inst, of Organic Synthesis, Riga, 1993, p.102 A. Sekiguchi, T. Yatabe, H. Naito, C. Kabuto and H. Sakurai, Chem. Lett., 1697 (1992). 

Stereochemistry and conformation of organogermanium, organotin and organolead compounds... 

It is the purpose of this chapter to summarize what is currently known about the stereochemistry and conformation of organogermanium, tin and lead compounds. Coverage is selective rather than exhaustive. The first section deals with compounds in which substitution by four different groups causes the metal atom to be stereogenic. We have limited our discussion to those cases in which at least three of the four substituents are alkyl or aryl. In this section we also briefly discuss pentacoordinated triorgano halostannanes. 

TABLE 1. Standard enthalpies of formation of organogermanium compounds (kJmol -i)a... 

Because of the controversy surrounding the use of static-bomb calorimetry for determining enthalpies of formation of organogermanium compounds1,2, the reliability of most data in Table 1 cannot be fully assessed. It is, however, possible to discuss generally some of the results. 

TABLE 2. Bond dissociation enthalpies in organogermanium compounds (kJmol-1)... 

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