Germylation, double

When HGeCl3-2 Et20 is reacted with acetylene259 or propyne260, a double germylation takes place ... 

Various alkylgermanes add across the Si-C double bond in the silylene complex 116 to yield germyl(silyl)tungsten complexes (Equation (201), Table 25).248... 

Only a few examples of the double germylation of C-C multiple bonds have been reported in the past decade. The catalytic reaction of a digermir-ane with acetylenes results in the formation of ring-expanded digermacyclo-pentenes [Eq. 21 )].63... 

Finally, the reaction of double germylation, such as formation of Cl3GeCH2CH2GeCl3 from ethylene and the etherate of trichlorogermane, is of great importance. 

Stanislav Kolesnikov, Stanislav N. Tandura and Oleg M. Nefedov VII. DOUBLE GERMYLATION... 

An example of double germylation was first discovered in the reaction of tricloroger-mane etherate with allyl chloride, as shown in equation 3076. Product 29 with two GeCl3 groups was obtained together with the product of condensation. 

It should be noted that tribromogermane forms the product of double germylation Br3GeCH2CH2GeBr3 in its reaction with ethylene even in the absence of ether80. 

A surprising example of a double germylation reaction was first found in the aromatic series. Addition of two GeCl3 groups into 9,10-positions of anthracene and 9-methylantracene (MA) proceeds in the absence of ether, but require bubbling of air through the reaction mixture simultaneously with addition of trichlorogermane81. 

In the presence of air at 5 °C, reaction of HGeCl3 with MA occurs in a different manner to give quantitatively the double germylation product rraws-9,10-bis(trichlorogermyl)-9-methyl-9,10-dihydroanthracene 35 (equation 33). A trans-configuration for 36 was suggested on the basis of comparison with an authentic sample of the ds-isomer obtained alternatively. This configuration is not sterically hindered and its formation can be ascribed to any mechanism. 

The nature of the unsaturated compounds dictate the reaction pathway to a great extent, but it still remains unclear why a radical mechanism predominates in some cases and why a radical hydrogermylation may lead to a radical double germylation. 

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