Trimethylstannyl-2,4-cycloheptadiene: A fluxional molecule

Abstract

Trimethylstannyl-2,4-cycloheptadiene (II) was synthesized and shown to be fluxional on the NMR time scale. The activation energy for the [1,5] trimethyltin migration is estimated to be ca. 18 kcal/mole. This value is compared with estimated activation energies of 14 kcal/mole for trimethylstannylindene (IV) and 6 kcal/mole for cyclopentadienyltrimethylstannane (I, E=Sn). 1,1-Dimethyl-4-trimethylstannyl-2,5-cyclohexadiene (VIII) was also synthesized and was shown to be non-fluxional.