Conformation of non‐aromatic ring compounds XXX: Dipole moments, NMR spectra and conformations of some trans‐1,2‐dihalogenocyclopentanes
- 1 January 1966
- journal article
- research article
- Published by Wiley in Recueil des Travaux Chimiques des Pays-Bas
- Vol. 85 (10) , 983-997
- https://doi.org/10.1002/recl.19660851003
Abstract
The dipole moments and NMR spectra of trans‐1,2‐dichloro‐ (I), trans‐1,2‐bromochloro‐ (II), trans‐1,2‐dibromo‐ (III) and trans‐1,2‐dibromo‐1‐methylcyclopentane (IV) in several solvents are reported. Special attention is given to the separation of the outer peaks in the low‐field part of the NMR spectra, due to the protons in the CHX‐moiety. This separation is equal to JAX + JBX and is shown to be correlated linearly with the square of the electric moment.It is proposed that the conformational properties of these molecules be described in terms of a solvent‐dependent dynamic equilibrium aa ⇌ ee, with the diaxial conformation predominating even in a highly polar solvent. Each of the two conformers may correspond to the half‐chair or the envelope model with the halogen atoms in the most puckered part of the ring. A limited pseudolibration about these forms is possible.Keywords
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