Fluorine-19F NMR Study on the Conformation Changes of 1,1,2,2-Tetra-fluoro-1,2-disilacyclohexanes

[[abstract]]Four 1,1,2,2-tetrafluoro-l,2-disilacyclohexadneer ivatives are synthesized. The conformation changes associated with ring inversion of these compounds are studied by full line-shape analyses of their lgF DNMR spectra. The activation parameters, AG*, AH*,an d AS*, are obtained with reasonable accuracy. The results show that the activation energy barrier of the ring inversion process is closely affected by the nature of the substituents at the 4 and 5 positions in cis orientation. A plausible mechanism for the ring inversion process, which involves a semiplanar transition state and a boat form intermediate, is proposed.[[fileno]]2010311010034[[department]]化學