Germyl anion

Germyl, Stannyl, and Plumbyl Anions The preparative methods for the synthesis of the germyl, stannyl, and plumbyl anions are essentially the same as those mentioned above for the silyl anions. The most widely used methods are (1) reduction of halides R3EX (R = alkyl, aryl E = Ge, Sn, Pb X = Cl, Br) with alkali metals and (2) reductive cleavage of the E-E bond of R3E-ER3 (R = alkyl, aryl E = Ge, Sn, Pb) with alkali metals or organolithium reagents. Due to the favorable polarization of the (E = Ge, Sn, Pb) bond, the direct metalation... 

An interesting bicyclic germyl anion 42 K was readily prepared by the reduction of bicyclic iodide 78 with KCg (Scheme 2.71). The Ge anionic center in 42 [K (dme)2] was highly pyramidalized with the normal value of the Ge-K bond distance (3.4324(10) A). However, in polar solvents (THF) the Ge-K bond dissociates to produce 42 as an SSIP featuring the free anion 42 . 

Evidence for such new anionic trichlorosilylation reactions based on hexachlorodisilane is now provided by the corresponding hexachlorodisilane cleavage of germyl- and stannylphosphanes 3 and 4. This type of reaction is a novel way to make Si-Ge and Si-Sn bonds under very mild conditions. 5 and 6 have been isolated in pure state, spectroscopic and analytical data confirm their composition. For the recovery of R2PMMe3 from R2PSiCl3, reasonable paths have been developed [2],... 

The electrochemical generation of the germyl anion has been the subject of a recent paper105. Evidence for its formation by SET reduction of Ph3GeH on Pt in DMF with tetrabutylammonium tetrafluoroborate is based on 13C NMR which shows a strong down-field shift of Ca 30 ppm for the ipso carbon of the anion. The anion tends to yield Ph3GeGePh3 above 20 °C, but is also trapped by reactions at —40°C with O2 and CH3I ... 

The Ge-Ge bond can undergo cleavage in reactions with [Bu4N]F to yield metal-free germyl anions, which can be employed in subsequent reactions with alkyl halides (Equation (210), Table 27) and carbonyl species (Equation (211), Table 28).266... 

By contrast, in the formally aromatic 277-electron system of 9886 [Eq. (20)] the average Ge-Ge bond distance is 2.326(4) A (98a) and 2.335(2) A (98b), thus 0.1 A shorter than in the anion 97.81 The three germanium atoms of this free germyl cation form an equilateral triangle. 

We have discussed the direct formation of anions by reaction of silyl- or germyl-lithiums with metal carbonyls (cf. Sect. 2.12) ... 

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