engleski

Investigation of double bond pyramidalization in 7-silanorbornenes and 7-germanorbornenes

Diels-Alder adducts of 1-sila-2, 3, 4, 5-tetraphenyl-1, 1-dimethyl-2, 4-cyclopentadiene and 1-germa-2, 3, 4, 5-tetraphenyl-1, 1-dimethyl-2, 4-cyclopentadiene with N-methylmaleimide, maleic anhydride and 7-oxanorbornenes were prepared by high pressure reactions. Their X-ray structures were determined and compared to the available literature data. In addition, DFT (B3LYP/6-31G*) quantum-chemical calculations were used to study their molecular and electronic structure. X-ray analysis revealed that extent of pyramidalization of the double bond. In all studied compounds is small or negligible and strongly depends on the nature and substitution pattern, as well as on the saddle effects of the crystal packing forces. B3LYP/6-31G* calculations were found to overestimate pyramidalization, presumably due to crystal packing forces.

pyramidalization; norbornenes; DFT calculations

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