A novel route for the preparation of dimeric tetraorganodistannoxanes

The reaction of polymeric diorganotin oxides, (R₂SnO)_<i>n</i> (R=Me, Et, <i>n</i>-Bu, <i>n</i>-Oct, <i>c</i>-Hex, <i>i</i>-Pr, Ph), with saturated aqueous NH₄X (X=F, Cl, Br, I, OAc) in refluxing 1,4-dioxane afforded in high yields dimeric tetraorganodistannoxanes, [R₂(X)SnOSn(X)R₂]₂, and in a few cases diorganotin dihalides or diacetates, R₂SnX₂. The reported method appears suitable for the synthesis of fluorinated tetraorganodistannoxanes. Identification of [R₂(OH)SnOSn(X)R₂]₂ (R=<i>n</i>-Bu; X=Cl, Br) and [R₂(OH)SnOSn(X)R₂] [R₂(X)SnOSn(X)R₂] suggest a serial substitution mechanism starting from [R₂(OH)SnOSn(OH)R₂]₂. X-ray crystal structure determinations are reported for [Me₂(AcO)SnOSn(OAc)Me₂]₂ (<b>29a</b>), [<i>i</i>-Pr₂(Br)SnOSn(Br)i-Pr₂]₂ (<b>20a</b>), [<i>c</i>-Hex2(F)SnOSn(F)c-Hex₂]₂ (<b>5a</b>) and [<i>c</i>-Hex₂(F)SnOSn(Cl)c-Hex₂]₂ (<b>36</b>), respectively. These show the presence of a central (R₂Sn)₂O₂ core that is connected, via the oxygen atoms, to R₂Sn entities. Acetate (<b>29a</b>) or halides (<b>5a, 20a, 36</b>) complete the coordination about the tin centres.<br /><br /><br />