Thermolysis of trimethylsilyl esters: an ultraviolet photoelectron spectroscopy study

1988 ◽  
Vol 66 (6) ◽  
pp. 1430-1439 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Michael A. Brook ◽  
Peter Hülser
Keyword(s):  
Acetic Acid ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Small Extent ◽  
Starting Material ◽  
Photoelectron Spectra ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Primary Products ◽  
Trimethylsilyl Trifluoromethanesulfonate

The thermolytic behaviour of trimethylsilyl trifluoromethanesulfonate, 1, trimethylsilyl trifluoroacetate, 2, and trimethylsilyl acetate, 3, has been investigated by ultraviolet photoelectron spectroscopy. Acetate 3 undergoes decomposition only to a small extent at 800 °C via the mechanism shown in Scheme 1 (X = Si); only acetic acid and starting material are detected. In contrast[Formula: see text]with this result, 1 and 2 decompose completely at 725–800 °C and yield products which cannot be derived via the mechanism shown in Scheme 1. Evidence is presented to support our proposal that the thermolysis of 1 yields trimethylsilyl fluoride, 6, and difluorooxathirane dioxide, 7, as primary products. The photoelectron spectra of 1, 2, 3, 6 and trimethylsilanol, 9, are presented. Molecular orbital eigenvalues of dimethylsilene, 4, dimethylsilanone, 5 (calculated using AMPAC and Gaussian 82), 6 and 9 (AMPAC) are reported. Molecular orbital contour diagrams are given for selected MOs of 6 and 9.

Thermolysis of N-alkylated ethylenediamines: an ultraviolet photoelectron spectroscopy study

1986 ◽  
Vol 64 (11) ◽  
pp. 2175-2183 ◽  
Author(s):  
N. H. Werstiuk
Keyword(s):  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
The Other ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Efficient Route

Thermolyses of N,N,N′,N′-tetramethylethylenediamine (1a), N,N,N′,N′-tetraethylethylenediamine (1b) and sym-N,N′-dimethylethylenediamine (1c) at 760–825 °C have been studied by ultraviolet photoelectron spectroscopy. Although the corresponding N-alkylated aminomethylene radicals were not observed, this study establishes that thermolysis of 1a is an efficient route to N-methylenimine (3a); methane, ethane, and ethene are the other major products. Diamine 1b yields, besides ethane, ethene, and propane, heretofore unreported N-ethylmethylenimine (3b). Diamine 1c yields imine 3a and methylenimine (3c), as well as hydrogen, methane, ethane, and ethene. Molecular orbital eigenvalues of the imines are calculated using HAM/3, MNDO, HF/STO-3G, HF/3-21G, and HF/6-31G* methods.

Gas-Phase Tautomerism in the Triazoles and Tetrazoles: A Study by Photoelectron Spectroscopy and ab Initio Molecular Orbital Calculations

1981 ◽  
Vol 36 (11) ◽  
pp. 1246-1252 ◽  
Author(s):  
Michael H. Palmer ◽  
Isobel Simpson ◽  
J. Ross Wheeler
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Relative Stability ◽  
Photoelectron Spectra ◽  
Equilibrium Geometry ◽  
Molecular Orbital Calculations ◽  
Methyl Derivatives

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.

Ultraviolet photoelectron spectroscopy study of the thermochromic phase transition in urethane-substituted polydiacetylenes

2007 ◽  
Vol 126 (18) ◽  
pp. 184905 ◽  
Author(s):  
Xiaoyu Wang ◽  
James E. Whitten ◽  
Daniel J. Sandman
Keyword(s):  
Phase Transition ◽  
Photoelectron Spectroscopy ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Spectroscopy Study

A Discussion on photoelectron spectroscopy - Photoelectron spectra of halides of elements in groups III, IV, V and VI

1970 ◽  
Vol 268 (1184) ◽  
pp. 59-76 ◽  
Keyword(s):  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectra ◽  
Orbital Structure

Photoelectron spectra of the halides of B, C, N, P, As, S, Se, Te and U are reported and interpreted in terms of molecular orbital structure. The experimental criteria which are used to identify the orbitals are briefly discussed. It is shown how the orbitals of the halides of the elements of different groups are related and how the additional electrons of molecules containing higher group atoms are accommodated in outer orbitals in a building up process somewhat analogous to that which occurs in atoms.

A Discussion on photoelectron spectroscopy - A study of the bonding in the group IV tetrahalides by photoelectron spectroscopy

1970 ◽  
Vol 268 (1184) ◽  
pp. 111-130 ◽  
Keyword(s):  
Ionization Potential ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Group Iv ◽  
Photoelectron Spectra

The photoelectron spectra excited by helium 21.2 eV radiation in the group IV halides, AB4, where A = C, Si, Ge, Sn, Ti and B = C1, Br, have been determined. The ionization potential data are discussed in terms of a simple molecular orbital description of the electronic structures.

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