Study of the transition state region in the Cl+HCl reaction by photoelectron spectroscopy of ClHCl−

1988 ◽  
Vol 88 (2) ◽  
pp. 1463-1465 ◽  
Author(s):  
R. B. Metz ◽  
T. Kitsopoulos ◽  
A. Weaver ◽  
D. M. Neumark
Keyword(s):  
Transition State ◽  
Photoelectron Spectroscopy ◽  
State Region

Investigation of the F+H2 transition state region via photoelectron spectroscopy of the FH−2 anion

1990 ◽  
Vol 93 (7) ◽  
pp. 5352-5353 ◽  
Author(s):  
A. Weaver ◽  
R. B. Metz ◽  
S. E. Bradforth ◽  
D. M. Neumark
Keyword(s):  
Transition State ◽  
Photoelectron Spectroscopy ◽  
State Region

Picturing the Transition-State Region and Understanding Vibrational Enhancement for the Cl + CH4→ HCl + CH3Reaction

1996 ◽  
Vol 100 (19) ◽  
pp. 7938-7947 ◽  
Author(s):  
William R. Simpson ◽  
T. Peter Rakitzis ◽  
S. Alex Kandel ◽  
Topaz Lev-On ◽  
Richard N. Zare
Keyword(s):  
Transition State ◽  
State Region ◽  
Vibrational Enhancement

scholarly journals Sampling the Folding Transition State Ensemble in a Tube-Like Model of Protein

10.29007/ml3c ◽  
2020 ◽  
Author(s):  
Ba Hung Nguyen ◽  
Hoang Trinh Xuan
Keyword(s):  
Free Energy ◽  
Transition State ◽  
Energy Surface ◽  
Sampling Technique ◽  
Small Region ◽  
Umbrella Sampling ◽  
Free Energy Surface ◽  
State Ensemble ◽  
State Region ◽  
Transition State Ensemble

We used the tube model with Go-like potential for native contacts to study the folding transition of a designed three-helix bundle and a designed protein G-like structure. It is shown that both proteins in this model are two-state folders with a cooperative folding transition coincided with the collapse transition. We defined the transition states as protein conformations in a small region around the saddle point on a free energy surface with the energy and the conformational root-mean-square deviation (RMSD) from the native state as the coordinates. The transition state region on the free energy surface then was sampled by using the umbrella sampling technique. We show that the transition state ensemble is broad consisting of different conformations that have different folded and unfolded elements.

Direct Ortho-Metallation of Aryl Substituted Heteroaromatic Ligands with TiCl 4 and ZrCl 4 - An Experimental and DFT Study with 2-Phenyl Indole as the Ligand.

2019 ◽  
Author(s):  
Gregory Arzoumanidis ◽  
Ernest Chamot
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Photoelectron Spectroscopy ◽  
Analytical Data ◽  
Phenyl Group ◽  
Building Blocks ◽  
One Pot ◽  
Polymerization Catalysis ◽  
Cyclometallated Complexes ◽  
C Nmr

TiCl 4 and ZrCl 4 each react with aryl substituted heteroaromatic ligands such as 2-Phenyl-1H-indole, to thermally undergo one-pot direct orthometallations, and yield new types of cyclometallated complexes. TiCl 4 coordinates at ambient temperature to form the indole complex ( 1 ), which undergoes isomerization to the indolenine ( 2 ). DFT calculations indicate that complex ( 2 ) is more stable than ( 1 ) by 6.4 kcal/mol. Upon warming to about 105°C, extrusion of HCl takes place with simultaneous orthometallation ( 3 ), yielding a metallacyclic complex ( 4 ). The mechanism of the orthometallation has been investigated by DFT, and the transition state c onfir med by IRC. At the elevated temperature the transition state ( 3 ) involves the synchronous transformation of four atoms, Ti, ortho C, H, and the apical Cl. The ortho C of the phenyl group acquires a partial positive charge through conjugation, forming a (C-H)δ + ...Clδ - interaction, with a simultaneous elongation and breaking of the Ti-Cl bond, resulting in the formation of a Ti-C bond. The latter bond is created at the same time a Ti-Cl bond is breaking, and an HCl is being formed, as illustrated in transition state ( 3 ). This HCl is retained in the crystal structure of the final product ( 4 ), by electrostatic interaction with one of the chloride ligands. The reaction sequence may be repeated with ZrCl 4 in place of TiCl 4 . Complex ( 4 ) has been isolated and characterized by solid state 13 C NMR CPMAS/DDMAS spectra, X-ray photoelectron spectroscopy (XPS), infrared and analytical data. The intermediate structures ( 1 through 4 ), as well as the sequence of ligand transformations to produce the ortho-metallated complex are supported by DFT calculations. The new cyclometallated complexes are thermally stable, unlike several other complexes featuring a Ti-C bond. They may have important applications, such as in α-olefin polymerization catalysis, and as building blocks in metalodrugs for cancer therapy.<br>

Reaction path Hamiltonian for the association reactions CH3 + H and CH3 + D

1992 ◽  
Vol 70 (7) ◽  
pp. 1897-1904 ◽  
Author(s):  
David M. Wardlaw
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
Reaction Path ◽  
State Theory ◽  
Hydrogen Separation ◽  
Coupling Coefficients ◽  
Symmetry Coordinates ◽  
Different Types ◽  
State Region ◽  
Reaction Path Hamiltonian

Coupling coefficients and normal mode frequencies appearing in the reaction path Hamiltonian formulated by Miller, Handy, and Adams have been calculated for the title reactions as a function of distance along the reaction path. The calculation of the coupling coefficients requires the use of symmetry coordinates which are described herein. It is found that the carbon–hydrogen separation provides an excellent representation of the reaction path coordinate, being linearly related to it. The coupling coefficients for CH3 + H and CH3 + D are approximately the same in the region of variational transition states and do not support the suggestion that an apparent isotope anomaly in the experimentally derived rates of these reactions might be attributable to different dynamics along the reaction path. The relative magnitudes of coupling coefficients for CH3 + H are used to assess some of the usual assumptions in variational transition state theory concerning separability of different types of motion in the transition state region.

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