ISSN:
1572-9001
Keywords:
Cage compounds
;
long C-C bonds
;
X-ray diffraction
;
molecular mechanics
;
semi-empirical calculations
;
ab initio calculations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 5-Methyl-2-phenylpentacyclo[5.4.0.02, 6.03, 10.05, 9]undecane-8, 11-dione,5-methyl-2-phenylpentacyclo [5.4.0.02,6.03,10.05,9]undecane-8-one-11-ol,and 5-methyl-2-phenylpentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-diol are three cage compounds which differ only in the oxidation state at C(8) and C(11). The three compounds contain a four-membered, a six-membered, and four five-membered rings fused into a cagelike structure. An X-ray structure analysis shows the C(1)-C(7) and C(9)-C(10) bonds in the diketo cage to be 1.606(2) and 1.586(2) Å, which are significantly longer than in the other two molecules. In order to assess the effects of strain, steric, and electronic factors in these compounds, we investigated the unsubstituted parent cage compounds and a series of derivatives by molecular mechanics (MM3), AMPAC (AM1), MOPAC (PM3), and GAUSSIAN 90 calculations. These data suggest that dipolar through space interactions are responsible for the bond elongation and not aπ −→σ * interaction, which has been postulated in parallelπ-systems originating from a common bond. A small degree ofπ −→σ * “through-bond” interaction may contribute to the lengthening in the dimethylene cage analogues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02278692
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