Organogermanium halides—

The oldest method for generating a Ge—Ge bond is the Wiirtz reaction from a tri-organogermanium halide and sodium1 ... 

III. ORGANOMETALLIC HALIDES OF GERMANIUM(IV), TIN(IV) AND LEAD(IV) A. Organogermanium Halides... 

Several methods, similar to those used to produce organosilicon compounds, are available for the preparation of germanium organyls. Organogermanium halides, which are the source of practically all other types of germanium organyls, can be formed by the direct reaction of aryl and alkyl halides with Ge/Cu alloys (equation 1). 

Figure 2 ORTEP diagram of the hypervalent organogermanium halide 31. Reproduced from Takeuchi, Y. Takase, Y. J. Organomet. Chem. 2004, 689, 3275-3277. 

The direct reduction of organogermanium halides using LiAlH4 is well known.95,98-112 Several species of interest have been prepared by this method including the germole 35 (Equation (79)),100 the mesityl derivative 36 (Equation (80)),101 the supermesityl derivative 37 (Equation (81)),102 and the optically active species 38 (Scheme ll),103 39 (Equation (82)),104 40 (Equation (83)),105 and 41 (Scheme 12).106... 

S.4.5.2. from Ge Halides or Organogermanium Halides with a Group-IIA Metal or Organomagnesium-Halide Reagent... 

J. Kuyper, Inorg. Chem., 1978, 17, 77. Oxidative addition of organogermanium halides to platinum. 

Around 1930 a few reactions between organogermanium halides and ammonia were studied by Kraus et al. (cf. 2). Further progress was slow and even by 1960 less than twenty organogermylamines and organogermazanes were known. Meanwhile, some other types of nitrogen containing compounds had been prepared, viz. isocyanides, isocyanates, and isothiocyanates. 

This reaction, first used by Winkler in 1886, is fairly satisfactory for tetra-alkyls (aside from the unpleasant making and handling of zinc alkyls), but it is difficult to control for the purpose of making organogermanium halides, and so is not much used any more. Mercury alkyls can be used instead of those of zinc. 

Closely related to the mixed oxides are the organogermanium alkoxides, which contain the linkage Ge-O-C and may be considered as alkoxide counterparts of the organogermanium halides. Indeed, they may readily be made from such halides by the action of sodium or lithium alkoxides, or by the action of the alcohols themselves if an HCl acceptor such as a tertiary amine also is used. Conversion reactions of organogermanium alkoxides with higher alcohols also are possible. The physical properties of some such alkoxides are given in Table 18. 

As expected, there also are many organogermanium sulphides and mercaptides. These are obtained by the reaction of organogermanium halides with sodium sulfide or mercaptide, or by reaction with H2S in the presence of an HCl acceptor. Some compounds are Usted in Table 19. 

U.lA ORGANOGERMANIUM HALIDES CONTAINING GERMANIUM-PSEUDOHALOGEN BONDS... 

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