Document Type

Article

Publication Date

7-1-2009

Publication Title

Journal of Physical Chemistry A

Volume

113

Issue

29

Publisher Name

American Chemical Society

Abstract

The equilibration of the saddle conformer of cyclotriveratrylene (CTV) oxime to the corresponding crown conformer was followed by (1)H NMR in five separate solvents, and kinetic and thermodynamic parameters were determined from the NMR data. The oxime saddle conformers of 3 are favored in CDCl(3) (K(eq) = [saddle]/[crown] = 1.4), whereas the CTV oxime crown conformer 3a is favored in three more polar solvents studied (DMSO-d(6), acetonitrile-d(3), acetone-d(6)). Surprisingly, the CTV oxime crown conformer is also slightly favored in the nonpolar solvent 1,4-dioxane-d(8). These behaviors are discussed in terms of hydrogen bonding, entropy, and possible host-guest considerations. An X-ray crystal structure was obtained for CTV monoketone, and structures of the different conformers of CTV, CTV ketone, and CTV oxime were calculated with semiempirical AM1 methods for direct comparison of their ground-state energies.

Comments

Author Posting © American Chemical Society, 2009. This is the author's version of the work. It is posted here by permission of American Chemical Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Chemistry A, Volume 113, Issue 29, July 1, 2009. http://dx.doi.org/10.1021/jp901796z

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