MOSSBAUER INVESTIGATIONS ON INTRAMOLECULARLY PHOSPHORYL COORDINATED ORGANOTIN COMPOUNDS

Alkyl 2, 2-bis(diisopropoxyphosphoryl)alkyl dihalostannanes of the gen eral formula of A: R(R(1))Sn(Br)CH2C(R(2))[P(O) ((OPr)-Pr-i)(2)](2) wi th R = Me, (t)Bu; R(1) = Cl, Br, and R(2) = H, Me have been investigat ed by means of Sn-119 Mossbauer spectroscopy and the results are compa red to those obtained from other spectroscopical methods (NMR, X-ray d ata). Due to donor-acceptor interactions of the metal center with both phosphoryl groups, the title compounds contain hexacoordinate tin ato ms in the solid state and trans arranged alkyl groups. The nature of t he R(2) group in A, H versus Me, changes the complexing behavior of th e difunctional ligand dramatically. If R(2) = H, intra- and inter-mole cular P = O-Sn interactions appear; resulting in the formation of dime rs. If R(2) = Me, discrete molecules containing a facial tridentate fu nctional ligand are obtained. The influence of these structural differ ences on the Mossbauer data and the chemical behavior of the compounds towards reduction by C8K is discussed, during the course of which fir st spectroscopical and chemical evidence of the formation of a distann ene (if R(2) = H) and stannylene (if R(2) = Me) is reported.