Pseudorotation reactions of biologically relevant oxyphosphoranes were studied by using density functional and continuum solvation methods. A series of 16 pseudorotation reactions involving acyclic and cyclic oxyphosphoranes in neutral and monoanionic (singly deprotonated) forms were studied, in addition to pseudorotation of PF5. The effect of solvent was treated by using three different solvat...

Pseudorotation in the pyrrolidine molecule was studied by means of femtosecond degenerate four-wave mixing spectroscopy both in the gas cell at room temperature and under supersonic expansion. The experimental observations were reproduced by a fitted simulation based on a one-dimensional model for pseudorotation. Of the two conformers, axial and equatorial, the latter was found to be stabilized...

Cyclic phosphates and certain related compounds undergo hydrolysis millions of times faster than their acyclic analogs, and specifically may undergo rapid hydrolysis of ester groups that are external to the ring.'-4 These unusual rate effects have recently been explained5 by postulating that the trigonal bipyramidal intermediates, formed during hydrolysis, undergo an internal inversion, or "pse...

The five-membered furanose ring is a central component of the chemical structure of biological nucleic acids. The conformations of the furanose ring can be analytically described using the concept of pseudorotation, and for RNA and DNA they are dominated by the C2'-endo and C3'-endo conformers. While the free energy difference between these two conformers can be inferred from NMR measurements, ...

The pseudorotation of tetrahydrofuran (THF) (C(4)H(8)O) has been studied using density functional theory, with respect to the valence orbital responses to the ionization potentials and to orbital electron and momentum distributions. Three conformations of THF, the global minimum structure C(s), local minimum structure C(2), and a transition state structure C(1), which are characteristic configu...

The most populated structure of tetrahydrofuran (THF) has been investigated in our previous study using electron momentum spectroscopy (EMS). Because of the relatively low impact energy (600 eV) and low energy resolution (DeltaE = 1.20 eV) in the previous experiment, only the highest occupied molecular orbital (HOMO) of THF was investigated. The present study reports the most recent high-resolu...

Femtosecond time-resolved Raman rotational coherence spectroscopy (RCS) is employed to determine accurate rotational, vibration–rotation coupling constants, and centrifugal distortion constants of cyclopentane (C5H10). Its lowest-frequency vibration is a pseudorotating ring deformation that interconverts 10 permutationally distinct but energetically degenerate "twist" minima interspersed by 10 ...

We extend our ab initio molecular dynamics methods to more exact wave functions, including complete active space multiconfiguration self-consistent-field (CASSCF) and full configuration interaction (full CI) wave functions. These extensions are critical for describing properly the dynamics of bond formation/ dissociation and isomerization, as we illustrate here by examining the bond dissociatio...

Abstract R. Stephen Berry (1931–2020) was a Harvard-educated American pioneer of molecular structure studies. He is most famous for the phenomenon pseudorotation and his studies intramolecular motion fluxionality. This remembrance focuses on this discovery. had broad interests in many other aspects structural chemistry physical also economics energy.