The thermal stability encapsulation in glass, and exchange reactions, of organotin compounds
The thermolysis of organotin compounds R3SnX (R=Ph, Bu, Cy, Neo, Bnz; X=Cl, OSnRa, SnR3, O2CR'), R2"SnO and R"Sn(O)OH (where R"=Bu, Oct) has been investigated by thermal analysis, gas chromatography and Mössbauer spectroscopy. Several decompositions of R3SnX occurred via disproportionation to the tetra- and di-organotin products. Organotin compounds were successfully encapsulated into sized metal acetate glasses, with little or no decomposition of the organotin. Both halide/acetate and oxide/acetate exchanges occurred in the melt; partial exchange was realised with sterically hindered trineophyltin chloride. Tin-tin and tin-sulphur bonds were unaffected by the acetate melt; and only tin-carbon bond cleavage found was with tribenzyltin chloride. Mössbauer spectra of the compounds encapsulated into the acetate glass generally had identical spectra to the pure compounds in those cases where no exchange occurred; in contrast when anion exchanges occurred the trapped organotin compounds had different Mössbauer spectra to those of the starting material and the exchange product. Reactions between BX3 (X=F, Br or Cl) and TiCl4 with R3SnCH2CH=CHR' (I, R=Me, Bu or Cy; R'=H or Me) were studied by NMR spectroscopy. Allyl group/bromide exchanges occur between I and BBr3 at (<50°C), at higher temperature (ca - 10°C) I (R=Me or Bu but not Cy) reacts further to give R2SnBr2. Reaction between BCl3 and I (R=Bu; R'=H) at (<50°C) proceeded to form only Bu3SnCl. No allyl group/fluorine exchange products were detected from the reaction between I and BF3.Et2O below -20OC, however at 25°C I (R=Me; R'=H) reacts readily with BF3.Et2O, the predominant soluble tin species being Me4Sn. Compounds I and TiCl4 at 30°C rapidly produce R3SnCl and (RCHCHCH2)TiCl3.