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Pseudorotations

Figure Bl.4.9. Top rotation-tunnelling hyperfine structure in one of the flipping inodes of (020)3 near 3 THz. The small splittings seen in the Q-branch transitions are induced by the bound-free hydrogen atom tiiimelling by the water monomers. Bottom the low-frequency torsional mode structure of the water duner spectrum, includmg a detailed comparison of theoretical calculations of the dynamics with those observed experimentally [ ]. The symbols next to the arrows depict the parallel (A k= 0) versus perpendicular (A = 1) nature of the selection rules in the pseudorotation manifold. Figure Bl.4.9. Top rotation-tunnelling hyperfine structure in one of the flipping inodes of (020)3 near 3 THz. The small splittings seen in the Q-branch transitions are induced by the bound-free hydrogen atom tiiimelling by the water monomers. Bottom the low-frequency torsional mode structure of the water duner spectrum, includmg a detailed comparison of theoretical calculations of the dynamics with those observed experimentally [ ]. The symbols next to the arrows depict the parallel (A k= 0) versus perpendicular (A = 1) nature of the selection rules in the pseudorotation manifold.
Viant M R, Cruzan J D, Luoas D D, Brown M G, Liu Kand Saykaiiy R J 1997 Pseudorotation in water trimer isotopomers using terahertz iaser speotrosoopy J. Phys. Chem. 101 9032-41... [Pg.1262]

The vibronic motion may be described by using the (p, 0, (p) coordinates. In particular, the wave functions for the pseudorotational motion along the hyperangle (p that encircles the origin in a X3 system may assume the form [11]... [Pg.594]

Similar to the case without consideration of the GP effect, the nuclear probability densities of Ai and A2 symmetries have threefold symmetry, while each component of E symmetry has twofold symmetry with respect to the line defined by (3 = 0. However, the nuclear probability density for the lowest E state has a higher symmetry, being cylindrical with an empty core. This is easyly understand since there is no potential barrier for pseudorotation in the upper sheet. Thus, the nuclear wave function can move freely all the way around the conical intersection. Note that the nuclear probability density vanishes at the conical intersection in the single-surface calculations as first noted by Mead [76] and generally proved by Varandas and Xu [77]. The nuclear probability density of the lowest state of Aj (A2) locates at regions where the lower sheet of the potential energy surface has A2 (Ai) symmetry in 5s. Note also that the Ai levels are raised up, and the A2 levels lowered down, while the order of the E levels has been altered by consideration of the GP effect. Such behavior is similar to that encountered for the trough states [11]. [Pg.598]

In this section, we extend the above discussion to the isotopomers of X3 systems, where X stands for an alkali metal atom. For the lowest two electronic states, the permutational properties of the electronic wave functions are similar to those of Lij. Their potential energy surfaces show that the baniers for pseudorotation are very low [80], and we must regard the concerned particles as identical. The Na atom has a nuclear spin " K, and K have nuclear... [Pg.604]

Total Nuclear Spin s Rovibronic Rotational Pseudorotational... [Pg.606]

The furanose rings of the deoxyribose units of DNA are conformationally labile. All flexible forms of cyclopentane and related rings are of nearly constant strain and pseudorotations take place by a fast wave-like motion around the ring The flexibility of the furanose rings (M, Levitt, 1978) is presumably responsible for the partial unraveling of the DNA double helix in biological processes. [Pg.344]

Fig. 1. Berry pseudorotation about pentacoordinate ( ) phosphorus, where (Q) represent fluorine atoms, (a) Original trigonal bipyramid (b) square... Fig. 1. Berry pseudorotation about pentacoordinate ( ) phosphorus, where (Q) represent fluorine atoms, (a) Original trigonal bipyramid (b) square...
The F nmr spectrum of this compound gives only one signal over a wide range of temperatures, a result attributed to Berry pseudorotation (144). No alkyl- or aryltetrabromoarsorane has been reported. There is, however, an early report on the preparation of tetraiodomethylarsorane from methylarsonic acid and hydriodic acid (145). [Pg.339]

Dioxolane also pseudorotates essentially freely in the vapor phase. 2,2 -Bi-l,3-dioxolane (128) has been shown by X-ray crystallography to have a conformation midway between the half-chair and envelope forms. The related compound 2-oxo-l 3-dioxolane (129) shows a half-chair conformation. This result is confirmed by microwave spectroscopy and by NMR data. Analysis of the AA BB NMR spectra of the ring hydrogen atoms in some 1,3-dioxolane lerivatives is in agreement with a puckered ring. Some 2-alkoxy-l,3-dioxolanes (130) display anti and gauche forms about the exocyclic C(2)—O bond. [Pg.35]

Phosphonium hexafluorophosphate, benzotriazolyl-N-hydroxytris(dimethylamino)-in peptide synthesis, 5, 728 Phosphonium salts chromene synthesis from, 3, 753 reactions, 1, 531 Phosphonium salts, vinyl-in pyrrole synthesis, 4, 343 Phosphonium ylides in heterocyclic synthesis, 5, 165 Phosphoramide, triethylene-as pharmaceutical, 1, 157 Phosphoramide, triethylenethio-as pharmaceutical, 1, 157 Phosphorane, pentaphenyl-synthesis, 1, 532 Phosphoranes, 1, 527-537 Berry pseudorotation, 1, 529 bonding, 1, 528... [Pg.743]

Cyclopentane is nonplanar, and the two minimum-energy geometries are the envelope and half-chair. In the envelope conformation, one carbon atom is displaced from the plane of the other four. In the half-chair conformation, three carbons are coplanar, vdth one of the remaining two being above the plane and the other below. The energy differences between the conformers are very small, and interconversion is rapid. All of the carbon atoms r idly move through planar and nonplanar positions. The process is called pseudorotation. [Pg.147]

The total spread in energies calculated for the four conformations is only 2.7 kcal/mol. The individual twist-chair conformations interconvert rapidly by pseudorotation. [Pg.148]

Concept of " pseudorotation introduced by R. S. Berry to interpret the stereochemical non-rigidity of trigonal bipyramidal PF5 (and SF4, ClFi) the 5 F atoms are equivalent (1953) due to interconversion via a square pyramidal intermediate. [Pg.474]

Figure 12.13 Interchange of axial and equatorial positions by Berry pseudorotation (BPR). Figure 12.13 Interchange of axial and equatorial positions by Berry pseudorotation (BPR).
P-F 153 pm). However, the F nmr spectrum, as recorded down to — 100°C, shows only a single fluorine resonance peak (split into a doublet by P- F coupling) implying that on this longer time scale (milliseconds, as distinct from instantaneous for electron diffraction) all 5 F atoms are equivalent. This can be explained if the axial and equatorial F atoms interchange their positions more rapidly than this, a process termed pseudorotation by R. S. Berry (1960) indeed, PF5 was the first compound to show this effect. The proposed mechanism is illustrated in Fig. 12.13 and is discussed more fully in ref. 91 the barrier to notation has been calculated as 16 2kJmol". ( ... [Pg.499]


See other pages where Pseudorotations is mentioned: [Pg.1256]    [Pg.180]    [Pg.210]    [Pg.211]    [Pg.358]    [Pg.362]    [Pg.586]    [Pg.594]    [Pg.594]    [Pg.595]    [Pg.598]    [Pg.599]    [Pg.602]    [Pg.613]    [Pg.358]    [Pg.34]    [Pg.13]    [Pg.634]    [Pg.821]    [Pg.916]    [Pg.129]    [Pg.159]    [Pg.450]    [Pg.457]    [Pg.391]    [Pg.17]    [Pg.23]    [Pg.90]    [Pg.82]   
See also in sourсe #XX -- [ Pg.133 ]

See also in sourсe #XX -- [ Pg.41 ]




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Barrier height pseudorotation

Barriers to pseudorotation

Berry Pseudorotation Mechanism (BPR)

Berry pseudorotation

Berry pseudorotation coordinate

Berry pseudorotation mechanism

Berry pseudorotation phosphorus compounds

Berry pseudorotation process

Conformation and Pseudorotation of Five-Membered Rings

Conformational pseudorotation

Correspondence Berry pseudorotation

Crystal conformation, pseudorotational

Cycloheptane pseudorotation

Cyclohexane pseudorotation

Cyclopentane pseudorotation

Energy barrier, to pseudorotation

Furanoses pseudorotation

Ground-State Isomerization Berry Pseudorotation

Hindered Pseudorotation

Inversion and Pseudorotation

Isomer, pseudorotating

Molecular pseudorotation, electronic

Oxyphosphoranes, pseudorotation

Phosphorus Berry pseudorotation

Phosphorus compounds, pentavalent, turnstile rearrangement and pseudorotation

Phosphorus compounds, pentavalent, turnstile rearrangement and pseudorotation in permutational isomerization

Phosphorus compounds, pentavalent, turnstile rearrangement and pseudorotation permutational isomerization

Potential energy surface pseudorotation

Pseudorotating ring molecules

Pseudorotation

Pseudorotation

Pseudorotation and the Trigonal Bipyramid

Pseudorotation at silicon

Pseudorotation barrier

Pseudorotation cycle

Pseudorotation defined

Pseudorotation five-membered ring

Pseudorotation in isomerization

Pseudorotation in isomerization of pentavalent phosphorus compounds

Pseudorotation lifetime

Pseudorotation mechanism

Pseudorotation path

Pseudorotation phase angle

Pseudorotation racemization

Pseudorotation radial coordinate

Pseudorotation square pyramid/trigonal bipyramid

Pseudorotation square pyramidal

Pseudorotation, and

Pseudorotation, energy barrier

Pseudorotation, furanose rings

Pseudorotation, ozonides

Pseudorotation, vibration-rotation

Pseudorotation-coordinate model

Pseudorotational angle

Pseudorotational conformational wheel

Pure Pseudorotation

Pyrazolo pyridine carbaribo-Cnucleoside, calculations on pseudorotational equilbrium of cyclopentane

Pyrrolidine, pseudorotation

Rearrangement pseudorotation mechanism

Rearrangements pseudorotations)

Restricted Rotation and Pseudorotation

Structural non-rigidity and Berry pseudorotation

Sugar pseudorotation phase angles

Sugar pseudorotation phase angles conformations

Trimer pseudorotating

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