Thermal and photochemical reactivity of cyclopropene derivatives: a semi-empirical molecular orbital study

The MINDO/3 semi-empirical MO method has been used to study the conversion of cyclopropene to vinyl carbene. In particular, the surfaces of the ground state and the first excited singlet and triplet states have been calculated. Additional calculations, including geometry optimization, have been carried out on vinyl substituted cyclopropenes. In general, the results are consistent with the known thermal and photochemical reactivities of cyclopropenes and the results of the few abinitio calculations on these species.

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The Tautomeric Conformers for the Molecules of Guanine and Cytosine. Some Rem arks about Their Stability

Zeitschrift für Naturforschung C ◽

10.1515/znc-1977-9-1033 ◽

1977 ◽

Vol 32 (9-10) ◽

pp. 870-873 ◽

Cited By ~ 2

Author(s):

Julio Marañon ◽

Oscar M. Sorarrain

Keyword(s):

Experimental Data ◽

Triplet States ◽

Excited Singlet ◽

Singlet And Triplet States ◽

Semi Empirical

Abstract In this paper we seek to determine the shape of the barrier between the normal and tautomeric conformers for some excited singlet and triplet states in the molecules of guanine and cytosine. The molecules are considered isolated and a particular movement of the H atom is analysed.The semi-empirical CNDO/2-CI has been used. The calculated results are compared with the available experimental data.

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Topological Study of the Protonation of Conjugated Compounds in the Ground State and in the First Excited Singlet and Triplet States

Zeitschrift für Physikalische Chemie ◽

10.1524/zpch.1976.103.1-4.001 ◽

1976 ◽

Vol 103 (1-4) ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

J. C. Rayez ◽

O. Chalvet ◽

J. Joussot-Dubien ◽

J. Hoarau

Keyword(s):

Ground State ◽

Triplet States ◽

Excited Singlet ◽

Singlet And Triplet States ◽

Conjugated Compounds

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A comparative molecular orbital study on the low lying singlet and triplet states of ethylene oxide

Theoretica Chimica Acta ◽

10.1007/bf00549696 ◽

1975 ◽

Vol 36 (4) ◽

pp. 329-338 ◽

Cited By ~ 12

Author(s):

Paul Mezey ◽

Roy E. Kari ◽

Azucena S. Denes ◽

Imre G. Csizmadia ◽

Ratnakar K. Gosavi ◽

...

Keyword(s):

Ethylene Oxide ◽

Molecular Orbital ◽

Triplet States ◽

Molecular Orbital Study ◽

Orbital Study ◽

Singlet And Triplet States

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Conformational analysis and electronic properties of bithiophene and terthiophene in their ground state as well as in their first excited singlet and triplet states

Chemical Physics Letters ◽

10.1016/0009-2614(95)01444-6 ◽

1996 ◽

Vol 250 (1) ◽

pp. 31-39 ◽

Cited By ~ 41

Author(s):

Michel Belletête ◽

Nicolas Di Césare ◽

Mario Leclerc ◽

Gilles Durocher

Keyword(s):

Conformational Analysis ◽

Electronic Properties ◽

Ground State ◽

Triplet States ◽

Excited Singlet ◽

Singlet And Triplet States

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Singlet and Triplet States of Aminonitrenes: An Ab Initio Molecular Orbital Study

Canadian Journal of Chemistry ◽

10.1139/v73-493 ◽

1973 ◽

Vol 51 (20) ◽

pp. 3303-3308 ◽

Cited By ~ 9

Author(s):

N. C. Baird ◽

R. F. Barr

Keyword(s):

Ab Initio ◽

Molecular Orbital ◽

Molecular Orbital Calculations ◽

Triplet States ◽

Density Distributions ◽

Molecular Orbital Study ◽

Triplet Splitting ◽

Optimum Geometry ◽

Singlet And Triplet States ◽

Carbonyl Substitution

Ab initio STO-3G molecular orbital calculations are reported for the lowest singlet and the lowest triplet state of the aminonitrenes H2NN, CH3(H)NN, F(H)NN, and HCO(H)NN. The optimum geometry calculated for the H2NN triplet is nonplanar (Cs symmetry), with N—N and N—H bond distances of 1.436 and 1.034 Å, and HNN and HNH angles both of 107.5°. The optimum singlet is predicted to be planar (C2v symmetry), with N—N and N—H distances of 1.276 and 1.041 Å respectively, and an HNN angle of 124°. An analysis of the calculated geometries and electron density distributions indicates that the "idealized" representations 3 and 5 are adequate to explain the bonding in the triplet and singlet respectively. The effects of methyl, fluoro, and carbonyl substitution upon the singlet–triplet splitting and upon the charge distribution are discussed. The optimum-geometry triplet is predicted to be slightly more stable than the optimum-geometry singlet in all cases.

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