Hydrides germanium

Chain reactions of heterocycles with participation of silicon and germanium hydrides 98AG(E)3072. 

Silicon forms numerous hydrides that have counterparts in the hydrocarbon series. However, the silanes are named with respect to the number of silicon atoms present. For example, Si2Hs is known as disilane, Si3H8 is trisilane, and so on. The situation is similar for the germanium hydrides. 

KGeH3, which is a very useful germanium hydride salt in various synthetic routes, is usually prepared by the reaction203 of GcIE with potassium in dimethoxyethane. It can also be made by the reaction20311... 

Germanium hydrides (as well as silicon hydrides) can be obtained in high yields by reduction of the corresponding halides or alkoxides by LiAlFLt in the presence of phase-transfer catalysts244. 

The most stable of the germanium hydrides, R GcI I4 (n = 0,1,2,3), are the tri-organogermanium hydrides, which are prepared by the reduction of the corresponding halides with lithium alanate, or with amalgamated zinc and hydrochloric acid5-7. 

The bond dissociation energies (BDE) of several alkyl- and aryl-substituted germanium hydrides were measured by the laser-induced photoacoustic effect22. The alkyl-substituted compounds exhibited similar BDEs to that of GeEU (81.6-82.6 kcal mol 1) while aryl substitution results in a slight weakening of the Ge—H bond (BDEs 79.2-80.2 kcal mol 1). 

The hydrogen-donor ability of germanium hydrides has been studied123 and reviewed.124... 

Alkynes react with the bulky germanium hydride (MejSdjGeH to selectively yield (Z)-alkenes (Equation (105)).67 The hydrogermylation of alkynols or alkynes can be catalyzed by a rhodium complex (Equation (106), Table 18) and some of the intermediates were identified (Scheme 16).132 Similar rhodium species react with alkynes to yield alkenyl complexes,133 and other transition metal complexes have been employed as hydrogermylation catalysts including those containing palladium.134,135... 

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... 

Silicon and germanium hydrides react with cobalt, manganese and rhenium carbonyls affording complexes having a silicon (or germanium)-metal bond. These reactions, described previously for inactive compounds have been used in the synthesis of optically active silyl and germyl-transition metals ... 

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