Electrophilic and nucleophilic addition to tin(II) compounds



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The reactions of aminotin(II) compounds and aminetin(II) halides with tri fluoroborane have been investigated. In Part I, the reactions of both a stoichiometric quantity and excess of trifluoroborane with bis(dimethylamino)tin(II) and bis(diethylamino)tin(II) are described. The reactions were monitored by NMR. The tensimetric titration method was also employed. The first site of BF[lowered 3] coordination was found to be the tin lone pair, and additional BF[lowered 3] coordinated to the amide nitrogens. In Part II, the reactions of tin(II)halide adducts of trimethylamine and dimethylsulfoxide, and chelated adducts of N,N,N',N'-tetramethyl ethylenediamine and di pyridyl with BFg are described. The nature of the coordinate bonding in the products has been determined by comparison of the results of various possible side-reactions. Whenever the tin(II) halide is participating in an adduct with an electron pair donor, subsequent coordination of BF[lowered 3] is on the tin site. The [raised 119]Sn, [raised 11]B, [raised 19]F and [raised 1]H NMR spectra of the products confirm the structure. Thus, the tin(II) halides exhibit electrophilic and nucleophilic properties simultaneously and are therefore named amphoadducts. All the BF[lowered 3]-coordinated tin(II) compounds reported here exhibit lessened reducing characteristics compared to tin(II) halides and may be regarded as psuedotin(II) compounds.