Conformational Averaging mainly of Static Gas Phase Structures

1 Conformational Averaging mainly of Static Gas Phase Structures 

Wiberg and coworkers investigated the OR temperature dependence of hydrocarbons. Different studies explored how the presence of an alkene chromophore, the conformer distribution, and vibrational modes affected the OR in small molecules. 

Wiberg et al. [171] gained information related to the origin of the change in optical rotation as functional of torsional angle, and thus the vibrational/rotational effects on their OR, by exploring a set of six achiral hydrocarbons, alkanes and alkenes from C2 to C4 at the B3LYP/6-31++G(d,p) level of theory. 

180 deg mL g 1 dm-1. For the nine neutral (S)-proline conformers, the specific rotations varied from —184 to 48 deg mL g-1 dm-1. For the six cationic (IS )-proline conformers, the specific rotations varied from —64 to —168 deg mL g 1 dm For the three anionic (S)-proline conformers, the specific rotations varied from —623 to +151 deg mL g-1 dm-1. The large magnitudes for the anionic species was rationalized by their low excitation energies which make the system more susceptible to small perturbations (see the SOS equation (2)). 

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