| Abstract
| - The microwave spectra of (methylenecyclopropyl)methanol (H2CC3H3CH2OH) and one deuterated species(H2CC3H3CH2OD) have been investigated in the 20−80 GHz spectral range. Accurate spectral measurementshave been performed in the 40−80 GHz spectral interval. The spectra of two rotameric forms, denotedconformer I and conformer IX, have been assigned. Both these rotamers are stabilized by intramolecularhydrogen bonds formed between the hydrogen atom of the hydroxyl group and the pseudo-π electrons on theoutside of the cyclopropyl ring, the so-called “banana bonds”. The carbon−carbon bond lengths in the ringare rather different. The bonds adjacent to the methylene group (H2C) are approximately 7 pm shorter thatthe carbon−carbon bond opposite to this group. It is found from relative intensity measurements of microwavetransitions that conformer IX, in which the hydrogen bond is formed with the banana bonds of the longcarbon−carbon bond, is 0.4(3) kJ/mol more stable than conformer I, where the hydrogen bond is formedwith the pseudo-π electrons belonging to the shortest carbon−carbon bond of the ring. The microwave studyhas been augmented by quantum chemical calculations at the MP2/6-311++G**, G3 and B3LYP/6-311++G**levels of theory.
|
