Germanium-Centered Radicals

The integral character of the CIDNP effects show a considerable difference in the g-values of the radical pair partners. One of these partners is a germanium-centered radical and the other is a hydrocarbon radical. 

The reactions of atoms or radicals with silicon hydrides, germanium hydrides, and tin hydrides are the key steps in formation of the metal-centered radicals [Eq. (1)]. Silyl radicals play a strategic role in diverse areas of science, from the production of silicon-containing ceramics to applications in polymers and organic synthesis.1 Tin hydrides have been widely applied in synthesis in radical chain reactions that were well established decades ago.2,3 Germanium hydrides have been less commonly employed but provide some attractive features for organic synthesis. 

As with silicon hydrides, the reaction of atoms or radicals with germanium hydrides is the key step for the majority of reactions forming germyl radicals. However, kinetic data for the reactions of organic radicals with germanium hydrides in solution are limited to carbon- and oxygen-centered radicals. 

Rate Constants for Reactions, of Carbon-Centered Radicals with Germanium Hydrides... 

When the same reaction was conducted with two equivalents of w-BuLi followed by alkylation with Mel, it gave the expected dimethylated germanium derivative almost quantitatively. However, the reaction mechanism might be more complex than the expected nucleophilic substitution by a germanium-centered dianion. A more complex radical... 

Of special interest are also the reactions of allyl-substituted element-centered radicals. For instance, AlIBu2Ge and dibutyl(2-methylallyl)germyl radicals undergo disproportionation reactions leading to derivatives of tetra- and divalent germanium . 

From this perspective, the combination of spin chemistry techniques and laser pulse photolysis should allow one to obtain the most valuable information on the formation and decay reactions of such active short-lived derivatives as alkyl-substituted germylenes and digermenes, as well as on germanium-centered free radicals ... 

Silicon-, Germanium-, and Tin-Centered Cations, Radicals, and Anions ... 

SILICON-, GERMANIUM-, AND TIN-CENTERED CATIONS, RADICALS, AND ANIONS... 

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