Germanium and Tin

The photochemical decomposition of [Gelv(ox)3]2-,800 and the light-induced reactions of Et3MC=CH (M = Ge or Sn) with BunSH601 have been discussed. 

In contrast with their behaviour on heating, cis- and fra/w-penta-l, 3-dienes produce the 1,4-addition products cis- and trans- Me3SnCH2C= CHEt on photolysis in Me3SnH.502 No products arising from Sn—C bond rupture could be observed after irradiation of 2-trimethylstannylbuta-1,3-diene, and the main products found were the isomers (81)—(83).603 

Evidence for the photochemical cleavage of the Sn—N bond as the primary step in reaction (100) has been adduced from cednp experiments.604 The reactions 

—Recent reports on solid-state photoprocesses of Pb compounds include investigations in the far-607 and near-i.r.608 of the effect of photodecomposition of Pb(N3)a, the low-temperature photoluminescence of Pb(N3)2,609 photoproduction of disorder in Pb(N3)2 and T1(N3),810 studies of the photolysis of PbCl2 

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The oxidation state -1-4 is predominantly covalent and the stability of compounds with this oxidation state generally decreases with increasing atomic size (Figure 8.1). It is the most stable oxidation state for silicon, germanium and tin, but for lead the oxidation state +4 is found to be less stable than oxidation state +2 and hence lead(IV) compounds have oxidising properties (for example, see p. 194). 

Thus we have shown that when s and p orbitals are available and s—p quantization is broken an atom can form four (or fewer) equivalent bonds which are directed towards tetrahedron corners. To the approximation involved in these calculations the strength of a bond is independent of the nature of other bonds. This result gives us at once the justification for the tetrahedral carbon atom and other tetrahedral atoms, such as silicon, germanium, and tin in the diamond-type crystals of the elements and, in general, all atoms in tetrahedral structures. 

Fig. 4.—Radial distribution curves for carbon and silicon tetrafluorides and silicon, germanium and tin tetrachloride.

Malrieu predicted qualitatively that the l-silaallene framework would be nonlinear. but how much the moiety would deviate from 180 was unclear. The first quantitative values were seen with the isolation and structural determination of the two 1-silaallenes 56 and 59a, whieh have very similar Si=C=C angles of 173.5 and 172.0, respectively (Table III). This is an average deviation of 7.3 from linearity—significant, but relatively small compared to the deviations shown by the germanium and tin substituted allenes. 

Silicon-, Germanium-, and Tin-Centered Cations, Radicals, and Anions ... 

SILICON-, GERMANIUM-, AND TIN-CENTERED CATIONS, RADICALS, AND ANIONS... 

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