Germanium carbon bond formation

Germanium-carbon multiple bonds, formation, 3, 709 Germanium-chalcogen bonds, reactivity, 3, 745 Germanium complexes with alkali metal bonds, 3, 748 with Isis // -arcnc chromium heteroatoms, 5, 340 with chromium carbonyls, 5, 208 coupling reactions, 3, 711 with CpMoCO, 5, 463... 

In summary, the four chemical systems described in this paper demonstrate the versatility and selectivity of electrochemical methods for synthesis and characterization of metal-carbon a-bonded metalloporphyrins. The described rhodium and cobalt systems demonstrate significant differences with respect to their formation, stability and to some extend, reactivity of the low valent species. On the other hand, properties of the electroche-mically generated mono-alkyl or mono-aryl germanium and silicon systems are similar to each other. 

Common methods for the formation of germanium-carbon bonds, including reactions of germanium halides with organolithium or Grignard reagents, are still used and have yielded some interesting new compounds. In addition, several novel methods for Ge-C bond formation have also been developed since the field was last reviewed. 

Inter-ring metal migrations, dynamic NMR studies, 1, 412 Intracyclic germanium-carbon bond formation large rings, 3, 706 small rings, 3, 703 Intramolecular Alder-ene reactions with metals, 10, 576 with palladium, 10, 568 with rhodium, 10, 575 with ruthenium, 10, 572 with transition metal catalysts, 10, 568 Intramolecular allylations, in cyclizations, with indium compounds, 9, 679... 

On the other hand, in covalently bonded materials like carbon, silicon, and germanium, the formation of energy bands first involves the hybridization of the outer s- and p-orbitals to form four identical orbitals, ilnh, which form an angle of 109.5° with each other, that is, each C, Si, and Ge atom is tetrahedrally coordinated with the other C, Si, and Ge atom, respectively (Figure 1.16), resulting in a diamond-type structure. 

An excellent discussion of the primary methods used for germanium carbon bond formation (direct synthesis, salt elimination, redistribution, and hydrogermylation) was provided in the first edition. The techniques all typically employ Ge(IV) starting materials. Key updates are provided below for these areas as needed. In the past decade, the application of Ge(II) starting materials has allowed observation of the following new germanium-carbon bond forming reactions C-X insertions, CH-insertions, CH-activations, and formal 4 + 2 cycloadditions. 

Germanium-carbon bond formation can also be achieved with Ge(II) by taking advantage of formal 4 + 2 cycloaddition reactions. For example, it was shown in the 1970s that GeCl2 will reaction directly with butadiene to form 1,1-dichlorogermacyclopent-3-ene, albeit in a low 15% yield. This general reaction was extended to include phenones and... 

These reactions include bond formation between carbon and the heteroatom such as silicon, tin, or germanium, and homocoupling of these heteroelemental... 

In 2002, the formation of a germanium-carbon bond directly from Ge02 was reported. The synthesis of MeGe(OMe)3 was accomplished by heating a mixture of Ge02 and 5% KOH to 350 °C in a fixed bed reactor while flowing dimethyl carbonate over the mixture (equation 1). 

An initial report of CH-activation for the formation of germanium-carbon bonds appeared in 2003 (Figure 4). 

Although several methods for the formation of germanium carbon bonds now exist, the chemistry of germanium carbon bond reactions remains woefiilly underdeveloped by comparison to sihcon and tin. The importance and utihty of many of the formation reactions will likely remain... 

This part concludes the description of the formation of carbon bonds to transition-and inner transition-metal bonds which is then followed by the formation of silicon, germanium, tin, and lead bonds to these metals. 

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