The dioximes 4–6 and the dimethoximes 7–9, which contain the functional groups in opposite positions of a six‐, eight‐, or ten‐membered ring, were synthesized. Their conformational properties and transannular interactions were investigated by spectroscopic (PE, 13C NMR) and theoretical (MMX, AM1, ab initio HF, and B3LYP) methods. While the cyclooctane derivatives 5 and 8 have conformations favourable for through‐space interactions of the π(CN) orbitals, in the other compounds no such interactions can be ascertained. Through‐space orbital interactions in the molecules with an eight‐membered ring lead to a splitting of the π(CN) MOs of 0.4 eV.
The bicyclic dioximes 4–6 and dimethoximes 7–9, which contain the functional groups in opposite positions of bridged eight‐membered rings, were synthesized. Their conformational properties and transannular interactions were investigated by spectroscopic (PE, 13C NMR) and theoretical (MMX, AM1, ab initio HF, and B3LYP) methods. While in the 3,7‐disubstituted bicyclo[3.3.1]nonane derivatives 5 and 8 the eight‐membered ring has a CC conformation favourable for through‐space interactions of the π(CN) orbitals, in the bicyclo[3.3.0]octane derivatives 4 and 7 as well as the 2,6‐disubstituted bicyclo[3.3.1]nonanes 6 and 9 the functional groups are in geometric orientations that are unfavourable for such interactions. Through‐space orbital interactions in the molecules with favourable conformations lead to a splitting of the π(CN) MOs of 0.4–0.6 eV.
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