MECHANISMS AND KINETICS OF THE ELEMENTOTROPIC REARRANGEMENTS OF AHYDRO-4,4,8,8-TETRAMETHYL-4,8-DISILA-SYM-INDACENE

The dynamic stereochemistry of silatropic rearrangements of ahydro-4,4 ,8,8-tetramethyl-4,8-disila-sym-indacene (dimer of 6,6-dimethyl-6-sila fulvene), which exists in solution as an equilibrium mixture of two in terconverting isomers, was studied. The mechanisms and complete kineti c scheme of rearrangements were established using H-1, C-13, and Si-29 2D quantitative EXSY NMR spectroscopy. It was found that the intercon version and degenerate rearrangements of the observed isomers proceed via two concurrent pathways due to the formation of different intermed iates. The activation parameters of the rearrangements were determined by means of total lineshape analysis of dynamic NMR (DNMR) spectra.