| Abstract
| - A series of alkyl- and aryl-substituted derivatives of cis,cis-1,2,5,6-tetrasilacycloocta-3,7-diene wereprepared. Isomerization of these compounds to the corresponding trans,trans-1,2,5,6-tetrasilacycloocta-3,7-dienes by exposure to Ru and Zr hydride complexes was explored. Experimental probesof the isomerization were consistent with a stepwise mechanism involving metal hydride addition/elimination rather than one involving radical intermediates. Analysis of the low energy conformersof the various cis and trans isomers of 1,1,2,2,5,5,6,6-octamethyl-1,2,5,6-tetrasilacycloocta-3,7-dieneusing density functional theory suggested the following trend in stability: trans,trans > cis,trans> cis,cis. The calculated trend in stability was consistent with the experimentally observedunidirectional isomerization of the carbon−carbon double bonds from all cis to all trans and supportsa cis,trans isomer as a tenable intermediate.
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