The Synthesis, Mössbauer and Infrared Spectra of some Dialkyltin Salts of Phosphorus Oxy-acids

Abstract

A number of dialkyltin(IV) salts of phosphorus oxy-acids R2Sn(PO2H2)2 (R = CH3, C2H5, n-C4H9), R2SnPO3X (R = CH3, C2H5, n-C4H9, X = H; R = CH3, X = F, OH), and [(CH3)2Sn]3(PO4)2 have been prepared in aqueous solution from the appropriate dialkyltin(IV) dichloride and the sodium salts of phosphorus oxy-acids.Infrared and 119Sn Mössbauer spectra of the dialkyltin dihypophosphites, R2Sn(PO2H2)2, are consistent with hexacoordination for tin with the alkyl groups in trans-octahedral positions and bidentate bridging hypophosphite groups coordinated through oxygens. For the dialkyltin phosphites, R2SnPO3X, polymeric structures with a non-linear R2Sn arrangement are involved, and the magnetic hyperfine Mössbauer spectrum (X = F) is consistent with either distorted trans-octahedral or distorted trigonal bipyramidal structures (with both apical or both equatorial methyl groups). In [(CH3)2Sn]3(PO4)2 the three tin environments are indistinguishable by Mössbauer spectroscopy, but the high value of the asymmetry parameter [Formula: see text] suggests penta- rather than hexacoordination about tin, for which at least one three-coordinate oxygen per formula unit must be invoked.