Complete analysis of H-NMR spectra of trans-1,2-dichlorocyclopentane and trans-1,2-dibromocyclopentane was performed with use of our total lineshape fitting algorithm VALISA. The resulting high precision spin-spin coupling constants were then applied to the problem of conformational analysis, yielding a continuos potential of pseudorotation for the studied compounds in CDCl3, CCl4, and CD3CN so...

A new method is presented to describe deformations of an N-membered planar ring (N-ring) molecule in terms of deformation vectors that can be expressed by a set of 2N-3 deformation amplitudes and phase angles. The deformation coordinates are directly derived from the normal vibrational modes of the N-ring and referenced to a regular polygon (N-gon) of unit length. They extend the conceptual app...

The variable mechanism for substitution of P-stereogenic phosphoryl chloride with alkynyl metallic reagents, which depends on temperature, stoichiometry of starting materials, and the structure of the nucleophilic reagent, is assumed as either SN2-like or Berry pseudorotation of pentacoordinated phosphorus intermediates, affording inversion and retention products, respectively. The formation of...

A set of pseudorotation coordinates is proposed for characterizing the puckering of the furanose ring. These are defined from the curvilinear displacements of the C1' and C4' atoms from the planar conformation. The present coordinates have some practical advantages over the ones currently used.

The Cu(II) atom in the title compound, [Cu(C(5)H(7)O(2))Cl(C(12)H(8)N(2))], shows a distorted square-planar coordination; the chelating N and O atoms occupy the basal sites and the Cl atom the apical site. The square-pyramidal character along the Berry D(3h)-C(4v) pseudorotation pathway is 92%.

We have used ab initio quantum mechanical (QM) methods to determine the potential energy of pseudorotation for 3,4-dihydroxy-5-methyl-2-(1-pyrollyl)tetrahydrofuran and 4-hydroxy-5-methyl-2-(1-pyrollyl)tetrahydrofuran, close analogues of 2′-deoxyribose and ribose sugars. The pyrrole is a substitute for the naturally occurring nucleic acid bases: adenine, thymine, guanine, cytosine, and uracil. A...

conformational properties of n-aryl-1-azacyclooctan-5- ones with a p-methyl, m-methyl, and p-methoxy group as a substituent have been studied by 1h-nmr, 13c-nmr and ir spectroscopies. transannular interaction of the two functional groups have been examined from the ring inversion barriers and the carbonyl vibrational frequencies with reference to the corresponding data of the respective monofun...