Pseudorotaion in cyclooctane, using spherical conformational landscape model

Abstract Medium sized rings and even small cyclic molecules have always challenged our static insights on them. They have thus forced us to propose models with conformers, connected in terms of energy and interconversions. The wheel-model of Lipnick et al. as well as the onion models of Hendrickson et al. are among the most sensible and sophisticated responses to such a demand. Here, DFT-ωb97xd/ 6–311 + G* computations confirmed by MP2/aug cc-pVTZ computations were used to fully investigate the energy, vibrations and full dynamics of 24 conformers. Then spherical conformational landscape SCL model was used to plot the conformational dynamics in cyclooctane for the first time. Classifications were done by a close inspection of the whole cast of conformers in cyclooctane, cyclopentane and cyclohexane. The fluxional Twist/Boat T/B ring coordinates were found to be a common feature in all the cyclic molecules studied. A new pictorial notion is suggested to present twist and boat conformers for all cyclic molecules in a generic sense. The simple, precise and universal conformational types presented here, unifies our perception of conformational dynamics in cyclic molecules, and paves the path towards a better analysis of cyclic motifs in natural products and bio-functional conformers.