Organogermanium hydrides

Several volatile organogermanium hydrides have been studied, principally to compare their barrier to internal rotation about the Ge—C bond with the analogous C—C and Si—C compounds. Although analysis of the microwave spectroscopic data which predominate in these studies often requires one or more of the molecular parameters to be assumed, the data taken as a whole indicate a number of trends in the bonding of these simple tetrahedral molecules (Table I). 

Comparison of the structures of mono- (120), di- (161), and trimethyl-germane (62) indicates no systematic variation in the Ge—C bond 

Bond Distances (A) and Angles (Decree) in Okganogekmanium Hydrides  

0 All data pertain to the gaseous state, derived from microwave spectroscopic data, unless indicated otherwise. h Gas phase, electron-diffraction data. 

CH3GeH2F relative to CH3GeH3 does not increase the barrier to rotation about this bond, although within the series CH3EH2F (E = C,Si,Ge), the potential energy barrier to rotation about the C—E bond does decrease with increasing E—C bond length, as expected (145). 

---

II. ORGANOMETALLIC HYDRIDES OF GERMANIUM(IV), TIN(IV) AND LEAD(IV) A. Organogermanium Hydrides... 

As for organogermanium hydrides, a simple organotin hydride, like tri-w-butyltin hydride, can be used for the reduction of structurally more complicated diorganotin dichlorides228 ... 

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. 

Another interesting group of compounds which have recently appeared are the chiral organogermanium hydrides which contain a resolved l,l -dithiobinaphthyl ligand (Equation (148)).195... 

The first representative of organogermanium hydrides R4 GeH (n = 1-3) was tri-phenylgermane. Kraus and Foster161 obtained it in 1927 by reaction of ISTLtBr and triphenylgermylsodium in liquid ammonia. Five years later Kraus and Flood148 similarly synthesized triethylgermane. 

Organogermanium hydrides are very good reducing agents. In 1957, Anderson337 showed that Et3GeH reduced transition metal salts to their lower valence state (Cu11 to Cu1, Tilv to Tim or Tin, Vlv to Vm, CrIV to Cl ) or to the free metals (Au, Hg, Pd, Pt). 

Triorganylgermanes readily reduce acyl chlorides173,276 and chloromethyl ether, preferably in the presence of traces of A1C13276,288,354,356. In 1964, it was found that organogermanium hydrides also readily reduced N-halosuccinimides354,365. 

SCHEME 50. Synthesis of polymer-supported organogermanium hydrides... 

In 1961, it was found that organogermanium hydrides R4 GeH reduced organic halogen derivatives in the absence of catalysts to the corresponding hydrocarbons . The reaction is easier the higher the value of n and the atomic number of the halogen. 

S.5.4. from Organogermanium Hydrides with Alkali Metals and Derivatives. 

Organogermanium hydrides, e.g., (CgF5)2GeBrH, also react with Et2Hg, and the presence of a Ge—Hg primary product may be inferred from the materials isolated ... 

S.3. from Organogermanium Hydrides with an Organomagnesium Halide-Reagent... 

---