Transition state spectroscopy of the I+HI reaction in clusters: Photoelectron spectroscopy of IHI-·Arn (n=1–15)

2001 ◽  
Vol 118 ◽  
pp. 221-232 ◽  
Author(s):  
Zhuan Liu ◽  
Harry Gómez ◽  
Daniel M. Neumark
Keyword(s):  
Transition State ◽  
Photoelectron Spectroscopy

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

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>

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

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>

scholarly journals Anion photoelectron spectroscopy of solvated transition state precursors

2003 ◽  
Vol 119 (2) ◽  
pp. 872-879 ◽  
Author(s):  
Harry Gómez ◽  
Giovanni Meloni ◽  
James Madrid ◽  
Daniel M. Neumark
Keyword(s):  
Transition State ◽  
Photoelectron Spectroscopy ◽  
Anion Photoelectron Spectroscopy

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

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