Reactions with germanium halides

Germanium-germanium double bonds 5.8.2.4.1, 5.8.4.2.4 triple bonds 5.8.4.2.4 Germanium halides reactions with... 

In order to test the generality of the synthesis, the reaction of (CzFsljHg with Gel was assessed. This reaction required a higher temperature, 135°, before it proceeded measurably. (Pentafluoroethyl)ger-manium triiodide was the only (perfluoroethyl)germanium halide produced, in 54% yield (15). From this reaction, perfluoroethyl iodide was also isolated (in 30% yield). The reactions of GeBr4 with (CF3)2Hg and (C2F5)2Hg were similar in nature (16). 

Germanium-carbon bonds can easily be formed in the reaction of organohydrido germanium lithium compounds with organic halides as shown in equation 3541. 

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. 

Silylated iminophosphines (15) react with alkyl halides to give the iminophos-phoranes (16).8 Similar reactions with Main-group IV and VII halides give the heterocycles (17) via the intermediate 1,2-addition products (18), which can be isolated in the case of germanium. 

The alkoxides of both oxidation states were obtained by metathesis of germanium halides (chlorides and iodides) with alkali alkoxides [1488, 1142, 857, 1535]. The yields can be increased by application of GeCl4 solvates with Py or NH3 or amines [3, 222] (method 5) and also by alcohol interchange of ethoxides (method 6) or alcoholysis of Ge[Si(NR3)2]2 [568, 1543] (method 4). The application of alkali alkoxides in the preparation of Ge(OR)4is possible in contrast to that of analogous derivatives of Sn(IV) and Zr due presumably to the much lower stability of corresponding alkoxogermanates the intermediate products of the corresponding reactions because of stability — of the tetrahedral coordination for Ge. The direct electrochemical preparation of Ge(OEt)4... 

Reaction of silylene 85 with silyl halides is believed to proceed via a similar reaction mechanism. The reactions are however less clean giving other products as well, such as silyldihalides 85X2. Similarly, during the reaction with germanium or tin(iv) chlorides, the dichloride 85C12 and the element(ll) chloride are formed <2006JOM811>. 

However, as also observed in germanium chemistry, a mixture of dihydride with an excess of lithiated reagent behaves as a stannyldianion in reactions with organic halides, polyformaldehyde or epoxides (Scheme 7)29, and it thus appears as an interesting synthetic reagent. 

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