Germanium, cyclopentadienyl

A stabilized heteroleptic germanium cyclopentadienyl complex was obtained which has an extremely long (2.369(1) A) Ge-Cl bond and an 2-bound Cp ring (Equation (238)).309... 

All studied model compounds can distinctly be divided into three groups (Table VII). The first group is composed of substances in which the sulfur, selenium or cyclopentadienyl anion acts as an anionic center. They exist only in open betaine forms, and their PES do not contain local minima corresponding to cyclic isomers. The second group contains compounds with arsonium cationic and oxide anionic centers and silicon and germanium betaines with arsonium and amide centers. They exist as cyclic isomers and their PES have no local minima corresponding to the open forms. Finally, the third group consists of six studied compounds with phosphonium cationic and oxide or amide anionic centers and arsonium-imide betaine. Their PES have minima for both cyclic and open forms separated by low barriers. 

Table 11 Examples of Cyclopentadienyl Derivatives of Bivalent Germanium, Tin and Lead...

Germanium-bridged complexes, with Zr(IV) and Hf(IV) cyclopentadienyl complexes, 4, 967 fluorenyl complexes, 4, 974 indenyl complexes, 4, 972... 

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). 

The situation in the cyclopentadienyl chemistry of tin is similar to that described for germanium several classes of cyclopentadienyl compounds are now known. The first compound in this series was reported by Fischer and... 

Treatment of hydrogermanium cyclopentadiene transition metal complexes with LDA can lead initially to a competition between the deprotonation of the hydrogen linked to germanium or to the cyclopentadienyl ring, but a migration of the germyl group to cyclopentadiene was actually observed (equation 192)9. 

Glass transition temperatures (Tg) for the poly(ferrocenyl)germanes are in a wide range of —7 to +124 °C and were found to depend on the nature of the substituents at germanium and the substituents at the cyclopentadienyl rings. Cyclovoltammetric measurements of... 

---