Mössbauer investigations on intramolecularly phosphoryl coordinated organotin compounds

Abstract

Alkyl 2,2-bis(diisopropoxyphosphoryl)alkyl dihalostannanes of the general formula of A∶R(R¹)Sn(Br)CH₂C(R²)[P(O)(OⁱPr)₂]₂ with R=Me,¹Bu; R¹=Cl, Br; and R²=H, Me have been investigated by means of¹¹⁹Sn Mössbauer spectroscopy and the results are compared to those obtained from other spectroscopical methods (NMR, X-ray data). Due to donor-acceptor interactions of the metal center with both phosphoryl groups, the title compounds contain hexacoordinate tin atoms in the solid state and trans arranged alkyl groups. The nature of the R² group in A, H versus Me, changes the complexing behavior of the difunctional ligand dramatically. If R²=H,intra- andinter-molecular P=O-Sn interactions appear, resulting in the formation of dimers. If R²=Me, discrete molecules containing afacial tridentate functional ligand are obtained. The influence of these structural differences on the Mössbauer data and the chemical behavior of the compounds towards reduction by C₈K is discussed, during the course of which first spectroscopical and chemical evidence of the formation of a distannene (if R²=H) and stannylene (if R²=Me) is reported.