Intramolecular mobility of pentacoordinated tin compounds

The ¹H and ¹³C NMR data for some N-methyl-5,5-dialkyldiptychthiaazstannolidines are reported. The differing coupling constants of the proton signals of the two nonequivalent Sn-alkyl groups suggest apical/equatorial positions for these groups at the pentacoordinated tin atom. The observed intramolecular process is explained by a dissociation-inversion mechanism.