Dimethyltin dihalides

Chlorine, bromine and iodine generally cleave germole and stannole rings850,147-150. From 1,1-dimethyltetraphenylgermole or -stannole, [(Z,Z)-butadienyl]metal halides are formed in a quantitative yield (equation 49). The methyl-metal bonds remain intact. In the tin series, further chlorination or bromination gives rise to dimethyltin dihalide and dihalobutadiene (equation 50). 

The complexes of dimethyltin dihalides were readily studied since they may be obtained easily, owing to the high acceptor ability of the starting halides, and may be purified by simple recrystallization or sublimation. 

M. Feser, R. Hoefer, O. Glemser, Z. Naturforsch. B 1974,29,716-718. Preparation and properties of sulfur oxide difluoride imide salts and their reaction with dimethyltin dihalides. 

The reactions of a-chloromethyl ethers ROCH2CI (R = Me, Et, or Bu) with powdered tin at 20—80 °C afford low yields of the dihalides (ROCH2)2-SnCIg. Dimethyltin dichloride may be prepared in 75—80 % yield by heating tin with methyl chloride in hexamethylphosphoramide at 140—150 C. Silicon tetrabromide is obtained by bromination of pure or commercial silicon, or ferrosilicon, in the presence of Cu, CuBr, or CuBr2 at 350—600 °C. Optimum yields are obtained at 500 C. A 97 % yield of germanium tetrachloride is obtained when vitreous germanium dioxide is treated with... 

The versatility does not end here, however, for diorganotin dihalides may be reacted with sodium to produce polytinsodium compounds 191, 209, 210). Thus, Kraus has shown that proper choice of the ratio of sodium to dimethyltin dibromide leads to 1,2-disodiotetramethylditin or 1,3-disodio-hexamethyltritin. Using this method a chain of five tin atoms has been obtained. 

Table 17.2 contains results for the organotin monomers tested. Whereas the majority exhibited some ability to inhibit microorganism growth, the best inhibition was by the dibutyltin dichloride and dimethyltin dichloride as expected. The ability for dibutyltin dichloride to be so active is positive as it has the lowest toxicity toward human beings. It is difficult to compare the inhibition results for the monomeric organotin dichalides with the polymers because the organotin dihalides probably have some solubility in the tested medium whereas the polymers have none. 

For illustrative purposes for natural polymers we will use dextran. Dextran is an extracellular polysaccharide synthesized by certain bacteria when grown on sucrose. The polymer consists mainly of branched chains of a(l->6)-linked )-glucosepyranose units. Reaction with organotin dihalides (here dimethyltin... 

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