REACTION OF TRIALKYLSTANNYLLITHIUM AND HEXAALKYLDISTANNANE. 1H AND 119Sn NMR STUDIES

Article abstract of DOI:10.1016/S0022-328X(00)93448-X

The reaction of hexamethyldistannane (Me3SnSnMe3) with metallic lithium in tetrahydrofuran (THF) has been studied by 1H and 119Sn NMR spectroscopy.All spectra displayed a single peak which moved gradually from the chemical shift of Me3SnSnMe3 (0.22 ppm in 1H NMR and -108.7 ppm in 119Sn NMR) into those of trimethylstannyllithium (Me3SnLi, -0.37 ppm, -182.7 ppm) in 2 h.A mixture of Me3SnSnMe3 and Me3SnLi in THF also showed only a single peak both in the 1H and 119Sn NMR spectra.There was a linear relationship between the chemical shift of the singlet and the amount of lithium per tri-methylstannyl group (Li/Me3Sn).The equilibration of the Me3Sn group between the two species was proposed as a plausible explanation for the apparent equivalency of Me3Sn and was supported by investigating two mixed alkyl systems.Both the Me3SnLi-Et3SnSnEt3 and Et3SnLi-Me3SnSnMe3 systems showed single Me3Sn and Et3Sn group resonances each in the NMR spectra.The chemical shift of Me3Sn vs. (Li/R3Sn) in 119Sn NMR spectra, however, deviated considerably to higher field from the linear relationship, while that of Et3Sn shifted to lower field.This can be interpreted in terms of the rapid exchange between Me3Sn and Et3Sn in the following two equilibria.