Germanium transition-metal complexes germylenes

Germylenes can be released thermally in the presence of a transition metal complex leading to the formation of a germanium-metal bond (Equation (193)).239 The reaction occurs at room temperature when a germylsilane is used as the synthon (Equation (194)).240... 

In a third class of 7t-cyclopentadienyl complexes, compounds of type LVIII are bound to a transition metal via the lone pair at the germanium atom. The first compounds in this series, the pentacarbonyl-[chloro(pentamethylcyclopentadienyl)germylene]chromium(0) (LIXa) and -tungsten(O) (LIXb) were synthesized by alkylation of the ylide complexes (CO)5M—GeCl2 THF according to Eq. (22) (201). Nucleophilic substitution reactions of LIXb lead to the alkyl- and amino-substituted complexes LIXc-e [Eq. (23)] (202). 

C. Synthesis of Transition Metal Germanium Double Bond Germylene Complexes... 

The early development of transition-metal germylene chemistry is summarized in earlier reviews4b-d. Therefore we summarize the transition-metal germylene chemistry developed after 1990. Such complexes can be divided into seven different types (I-VII) depending upon the nature of bonding between the metal and germanium atom ... 

TABLE 8. X-ray structural data of transition metal germanium complexes with bridging germylene ligands... 

Treatment of Mo(II) , W(II) and Au(I) complexes with one equivalent of GeCl2 dioxane, in CH2CI2 at —78°C and subsequent wanning to room temperature, resulted in rapid and clean insertion of germylenes into the metal-hydrogen or metal-chlorine bond . This is a convenient route to synthesize functionalized transition-metal germanium compounds The reaction is exemphfied in equations 18 and 19. 

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