Erk, Çakıl2024-04-242024-04-241989Erk, Ç. (1989). 13C-dipole dipole relaxation time and internal motions of oligo cyclicethers and ether-esters. Part IV. The mechanism and activation energies of the ring Pseudorotation of 15.Crown.5, 18.Crown.6 and 2,6-dioxo-18.crown.6. Journal of Molecular Liquids, 40(1), 1-15.0167-7322https://doi.org/10.1016/0167-7322(89)80046-7https://hdl.handle.net/11468/23282https://www.sciencedirect.com/science/article/abs/pii/0167732289800467?via%3DihubThe 13C dipole-dipole relaxation time values of 1,4,7,10,13- pentaoxacyclopentadecane,(15.Crown.5) and 1,4,7,10,13,16-hexaoxa cyclooctadecane,(18.crown.6) in CDCl3 and 2,6-dioxo-1,4,7,10,13,16 -hexaoxacycloctadecane,(2,6-do-18.crown.6) were determined in CD2Cl2 at 15 MHz of various temperatures by inversion recovery method. The results observed in frequency range of (WO+WH2T2«1 extreme narrowing conditions were explained in terms of internal motions of macrocyclic backbone and the ring isomerization. The free energies obtained from the 13C dipole-dipole relaxation time measurments were assigned properly to the pseudorotation rate and the conformational barrier of the oxyethylene groups of the macrocyclic ethers and ether-ester. The segmental motion CC and CO bonds of dioxo-hexaoxa ether, observed as the specific TDD1 and energy barrier of different 13C nuclei was also discussed.eninfo:eu-repo/semantics/closedAccessArticle4011152-s2.0-001156975110.1016/0167-7322(89)80046-7Q1