Fast kinetics studies of the Lewis acid–base complexation of transient stannylenes with σ- and π-donors in solution

2018 ◽  
Vol 20 (31) ◽  
pp. 20555-20570 ◽  
Author(s):  
Ian R. Duffy ◽  
William J. Leigh
Keyword(s):  
Lewis Acid ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Acid Base ◽  
Dft Methods ◽  
Fast Kinetics ◽  
Kinetics Studies ◽  
Reported Data

The complexation of SnMe2 and SnPh2 with a variety of σ- and π-donors and its effects on their dimerization reactions has been studied by laser flash photolysis and DFT methods, and compared to reported data for the Si and Ge homologues.

Substituent effects on silene reactivity — Reactive silenes from photolysis of phenylated tri- and tetrasilanes

2008 ◽  
Vol 86 (12) ◽  
pp. 1105-1117 ◽  
Author(s):  
William J Leigh ◽  
Andrey G Moiseev ◽  
Eugenie Coulais ◽  
Farahnaz Lollmahomed ◽  
Mohammad S Askari
Keyword(s):  
Phenyl Ring ◽  
Kinetic Data ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Substituent Effects ◽  
Laser Flash ◽  
Acetonitrile Solution ◽  
Ortho Position ◽  
Absolute Rate ◽  
Reported Data

Laser flash photolysis of 2-phenylheptamethyltrisilane (5d), 2,2-diphenylhexamethyltrisilane (5e), and phenyltris(trimethylsilyl)silane (5f) in hexane and acetonitrile solution affords strong, long-lived transient absorptions centered in the 440–470 nm range, which are assigned to the transient silenes formed via [1,3]-trimethylsilyl migration into the ortho-position of a phenyl ring on the basis of their UV–vis spectra and kinetic data for their reactions with methanol (MeOH), acetic acid (AcOH), acetone, 2,3-dimethyl-1,3-butadiene (DMB), carbon tetrachloride (CCl4), and oxygen. The silene derivatives are formed along with the corresponding silylenes (SiMePh, SiPh2, and Si(SiMe3)Ph, respectively) upon photolysis of these compounds in solution, and indeed, weak, short-lived transient absorptions assignable to the silylenes can also be detected in laser photolysis experiments with the three compounds in hexane, superimposed on the much more prominent absorptions due to the silenes. The silylene absorptions are quenched by MeOH and triethylsilane (Et3SiH) with absolute rate constants varying over the narrow ranges of (1.1–1.8) × 1010 (mol/L)–1 s–1 and (2.5–3.6) × 109 (mol/L)–1 s–1, respectively, in excellent agreement with previously reported values for SiPh2 and SiMe2 under the same conditions. The kinetic data obtained for the silenes are compared to previously reported data for the reactions of the same substrates with the related silenes (6a–6c) formed by photolysis of pentamethylphenyl-, 1,1,1,2-tetramethyl-2,2-diphenyl-, and 1,1,1-trimethyl-2,2,2-triphenyldisilane (5a–5c, respectively) under similar conditions. The comparison provides the first systematic, quantitative assessment of the stabilizing effects of trialkylsilyl substitution at the silenic silicon atom in silene derivatives.Key words: silene, silylene, trisilane, tetrasilane, kinetics.

Acid–base properties in the triplet state of aromatic ketones studied by nanosecond laser flash photolysis

1984 ◽  
Vol 62 (10) ◽  
pp. 2041-2046 ◽  
Author(s):  
Haruo Shizuka ◽  
Ehichi Kimura
Keyword(s):  
Triplet State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Nanosecond Laser ◽  
Acid Base ◽  
Aromatic Ketones ◽  
Acid Base Equilibrium ◽  
Nanosecond Laser Flash Photolysis ◽  
Base Properties

Acid–base properties in the triplet state of aromatic ketones in H2O–CH3CN (4:1) mixtures have been studied by means of nanosecond laser flash photolysis. The acidity constants pKa(T) in the triplet state were determined by the Tn ← T1 absorbance titration curve, the Ware plot, and the Rayner–Wyatt plot. Good agreement among them shows that the acid–base equilibrium in the T1 state of aromatic ketones is established during the triplet lifetime. A linear relation between pKa(T) and the Taft σ* values was obtained for phenyl alkyl ketones.

Primary Photochemical Processes of the Phototoxic Neuroleptic Cyamemazine: A Study by Laser Flash Photolysis and Steady State Irradiation

2004 ◽  
Author(s):  
Patrice Morlière ◽  
Francisco Bosca ◽  
Miguel Miranda ◽  
José Castell ◽  
René Santus
Keyword(s):  
Steady State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Photochemical Processes

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

A Laser Flash Photolysis and Pulse Radiolysis Study of Primary Photochemical Processes of Flumequine¶

2000 ◽  
Vol 72 (4) ◽  
pp. 451 ◽  
Author(s):  
M. Bazin ◽  
F. Bosca ◽  
M. L. Marin ◽  
M. A. Miranda ◽  
L. K. Patterson ◽  
...  
Keyword(s):  
Pulse Radiolysis ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Photochemical Processes

Laser Flash Photolysis in a O3 / Cl2 Mixture in a Very Low Pressure Flow System

2005 ◽  
Author(s):  
Jorge Codnia ◽  
Francisco Manzano ◽  
María Laura Azcárate
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Flow System ◽  
Laser Flash ◽  
Low Pressure ◽  
Pressure Flow

Laser Flash Photolysis Studies of the UVA Sunscreen Mexoryl® SX

1999 ◽  
Vol 70 (3) ◽  
pp. 292
Author(s):  
Ann Cantrell ◽  
David J. McGarvey ◽  
Louise Mulroy ◽  
T. George Truscott
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

Singlet Methylene Removal Rate Constants from the (0,1,0) Vibrational Level: Enhancement via Complex-Mediated Vibrational Relaxation

2001 ◽  
Vol 215 (6) ◽  
Author(s):  
M.A. Buntine ◽  
G.J. Gutsche ◽  
W.S. Staker ◽  
M.W. Heaven ◽  
K.D. King ◽  
...  
Keyword(s):  
Vibrational Level ◽  
Rate Constants ◽  
Vibrational Relaxation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Removal Rate ◽  
Laser Flash ◽  
Laser Absorption ◽  
Photolysis Laser ◽  
Singlet Methylene

The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene,

Electron transfer sensitized photolysis of 'onium salts

1988 ◽  
Vol 66 (2) ◽  
pp. 319-324 ◽  
Author(s):  
R. J. DeVoe ◽  
M. R. V. Sahyun ◽  
Einhard Schmidt ◽  
N. Serpone ◽  
D. K. Sharma
Keyword(s):  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Quantitative Model ◽  
Intersystem Crossing ◽  
Single Electron Transfer ◽  
Onium Salts ◽  
Encounter Complex ◽  
Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

Phototransformations of bridgehead-substituted dibenzobarrelenes. Steady-state and laser flash photolysis studies

1987 ◽  
Vol 52 (25) ◽  
pp. 5512-5517 ◽  
Author(s):  
S. Pratapan ◽  
K. Ashok ◽  
D. R. Cyr ◽  
P. K. Das ◽  
M. V. George
Keyword(s):  
Steady State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash
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