American Chemical Society
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Synthesis, X-ray, and DFT Study of the Double-Bond Pyramidalization in 1,7,8,9-Tetraphenyl-4,10,10- trimethyl-4-aza-10-silatricyclo[,6]deca-8-ene-3,5-dione and Its Germanium Analogue

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journal contribution
posted on 2006-01-02, 00:00 authored by Davor Margetić, Yasujiro Murata, Koichi Komatsu, Mirjana Eckert-Maksić
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 and maleic anhydride were prepared by high-pressure reactions. Their X-ray structures were determined and compared to literature data. In addition, the B3LYP/6-31G* method was used to study their molecular and electronic structure. X-ray analysis revealed that the extent of pyramidalization of the double bond in all studied compounds is small (molecules 1 and 2) or negligible (3). B3LYP/6-31G* calculations were found to overestimate pyramidalization by 5.3−9.4°, presumably due to crystal-packing forces. The effect of phenyl groups on the geometry of the double bond is discussed.