| Popis: |
Both the di-endo, (I), and the 2-endo-3-exo, (II), diastereomers of the title keto acid (C 15 H 16 O 3 ) crystallize as centrosymmetric carboxyl dimers, whose hydrogen bonding does not involve the ketone function [(I) O…O = 2.635 (3), (II) O…O = 2.675 (2) A]. Conformational differences between (I) and (II) include significant rotations of the carboxyl group and of the benzoyl moiety relative to the bicycloheptane skeleton, plus a slight rotation of the phenyl ring relative to the ketone. Steric interactions involving the di-endo substituents in (I) produce significant twisting of the bridged bicyclic structure, which is essentially absent in (II). A C-H...O close contact at 2.58 A was found for (I), involving the ketone, and at 2.49 A for (II), also involving the ketone. |
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