Ylides, germylene

Decomposition with the elimination of arsenic or phosphorus ylide and formation of silylene (germylene, stannylene) Me2E14, which represents the process inverse to the synthesis of these betaines. 

The formation of betaines in the reaction of silylenes (germylenes, stannylenes) Me2E14 (E14 = Si, Ge, Sn) with ylides H2C=E15Me3 (E15 = P, As) under gas-phase conditions occurs without a barrier as a strongly exothermic process. The thermal effects of the reactions are presented in Table XVII. 

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). 

In addition to the stable germenes mentioned above, an ylide-type compound 56 was synthesized by the reaction of the nitrogen-substituted germylene 45a with bis(dialkyl-amino)cyclopropenylidene 55 prepared in situ by the treatment of cyclopropenium cation... 

---