Organogermanium compounds, determination

Organogermanium compounds can be mineralized by wet oxidative digestion for 4 h at 70°C, in aqueous potassium persulphate, at pH 12. After dilution to an adequate concentration germanium can be determined by ICP-AES (inductively coupled plasma atomic emission spectrometry)9. 

Organosilicon and organogermanium compounds were separated at 330-350 K on a Cromaton column coated with squalene. Improved quantitative determination was achieved by accumulation of preliminary decomposition products of the organometallic compounds in a graphite atomizer, followed by ETAAS32. 

TABLE 2. Structural determination of organogermanium compounds by NMR spectroscopy... 

Electrochemistry of organogermanium compounds is still insufficiently studied. However, a systematic electrochemical study of basic germanium chlorides HCieCh and GcCI4 was carried out41,42. The main principles of the electrode processes and the nature of the intermediates formed were determined. 

Recent advances in Ge NMR spectroscopy are reviewed. Following the introduction (Section 1), Section 2 describes recently determined chemical shifts and linewidths for a variety of organogermanium compounds which range from normal (tetravalent) to hypercoordinated (up to heptavalent) species. The role of linewidth as evidence for hypercoordination is discussed. In Section 3, coupling constants, relaxation times and relaxation mechanisms are discussed in detail, showing that in some cases a mechanism other than quadrupolar is involved. In the last section, high-resolution solid-state Ge NMR spectroscopy is covered which has not been treated in previous reviews. 

In the 1980s and early 1990s, Ge NMR spectra of a large number of relatively simple organogermanium compounds were determined using FT NMR instruments (in most cases 90-100 MHz instruments) with low frequency probes. One such example is... 

The authors believe that in the case of organogermanium compounds, the relaxation mechanism in the solid state is the same as that in solution where the quadrupolar mechanism was proved predominant. They could confirm the absence of a dipolar mechanism by determining that the NOE enhancement factor is zero for 38. 

The phenylfluorone method has been used for determining germanium in biological samples [56], water [57], ores and minerals [11,58], coal and coke [9,14,59], coal ashes [16], gallium [60], organogermanium compounds [61], thin germanium-niobium films [62]. The flow-injection technique has been applied for determining Ge in pharmaceutical products [63]... 

Flinn, C. G., Walter, W. A., Gas Chromatographic Determination of Organogermanium Compounds by Surface or Gas-phase Luminescence, J. Chromatog. 186 [1979] 299/306. 

The Ge NMR chemical shifts of several methyl-and phenyl-substituted germacyclohexanes have been determined, and it has been shown that the chemical shifts are very sensitive to steric effects and can provide a useful tool for the conformational analysis of organogermanium compounds. 

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