Halogen switching of azacarbenes C<sub>2</sub>NH ground states at ab initio and DFT levels

Kassaee, M.Z.; Ghambarian, Mehdi; Musavi, S.M.

doi:10.1002/hc.20442

Cited by 23 publications

(10 citation statements)

References 99 publications

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“…For the bent singlet and cyclic singlet isomers in Tables 2 and 3, respectively, there are no experimental data available, and the only previous theoretical results were obtained at the QCISD(T)/D95** level of theory 59 (Kassaee et al 39 did not report equilibrium structures nor harmonic frequencies). Thus their bond distances are much too long and the stretching harmonic frequencies are too high relative to our best results.…”

Section: A Equilibrium Structures Harmonic Frequencies and Equilibrmentioning

confidence: 99%

“…Therein he found that the most stable singlet species corresponds to the cyclic isomer (7.7 kcal/mol above the ground state quasilinear triplet structure), followed by the bent singlet isomer at 13. 39 studied the singlet and triplet isomers of HC 2 N and found that the only low energy isomers are the ground state quasilinear triplet, the cyclic singlet, and the bent singlet HCCN isomer. Specifically, using G2 theory they found that the cyclic singlet was 5.0 kcal/mol higher in energy that the ground state triplet, and the bent singlet isomer is 7.6 kcal/mol higher than the ground state triplet.…”

Section: Introductionmentioning

confidence: 99%

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Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Inostroza

Huang

Lee

2011

The Journal of Chemical Physics

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Highly correlated ab initio quartic force field (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC 2 N isomers. Specifically, the ground state quasilinear triplet and the lowest cyclic and bent singlet isomers are included in the present study.Extensive treatment of correlation effects were included using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Dunning's correlation-consistent basis sets cc-pVXZ, X=3,4,5, were used, and a three-point formula for extrapolation to the one-particle basis set limit was used. Core-correlation and scalar relativistic corrections were also included to yield highly accurate QFFs. The QFFs were used together with second-order perturbation theory (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schrödinger equation. The quasilinear nature of the triplet isomer is problematic, and it is concluded that a QFF is not adequate to describe properly all of the fundamental vibrational frequencies and spectroscopic constants (though some constants not dependent on the bending motion are well reproduced by perturbation theory). On the other hand, this procedure (a QFF together with either perturbation theory or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC 2 N.

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Section: A Equilibrium Structures Harmonic Frequencies and Equilibrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Inostroza

Huang

Lee

2011

The Journal of Chemical Physics

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“…Many experimental and computational methods were carried out for the structures and the relative energies of some isomers of this system. A lot of studies have revealed that there exist many isomers with different kind of geometries (linear, bent or cyclic) or different multiplicity (singlet or triplet) having similar energies for the HC 2 N molecules [19][20][21][22][23][24][25][26][27][28][29][30] . Lee et al have characterized the quasilinear triplet, bent singlet, and cyclic singlet HC 2 N isomers and determined their molecular properties with a series of highly accurate ab initio level of theory 27 .…”

Section: -13mentioning

confidence: 99%

Insights Into the Reaction Mechanism Between Azacyclopropenylidene and Azacyclopropane: A Theoretical Study

Tan

2015

J. Chil. Chem. Soc.

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The reaction mechanism between azacyclopropenylidene and azacyclopropane has been systematically investigated employing the second-order Møller-Plesset perturbation theory (MP2) method to better understand the azacyclopropenylidene reactivity with three-membered ring compound azacyclopropane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. For the first step of this reaction, azacyclopropenylidene can insert into azacyclopropane at its C-N bond to form a spiro intermediate IM. Through the ring-opened step at C-C bond of azacyclopropenylidene fragment, IM can transfer to product P1, which is named as pathway (1). On the other hand, through the H-transferred step and subsequent ring-opened step at C-N bond of azacyclopropenylidene fragment, IM can turn into product P2, which is named as pathway (2). From the thermodynamics viewpoint, the P2 is the dominating product. From the kinetic viewpoint, the pathway (1) of formation to P1 is primary.

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“…Many studies have revealed that there are many isomers with different kinds of geometries (linear, bent or cyclic) or different multiplicities (singlet or triplet) having similar energies for the HC 2 N molecules. [19][20][21][22][23][24][25][26][27][28][29][30] Lee et al have characterized the quasilinear triplet, bent singlet, and cyclic singlet HC 2 N isomers and determined their molecular properties with a series of highly accurate ab initio levels of theory. 27 In addition, the cyclic HC 2 N isomer was found to be an intermediate between the interconversion of the bent HCCN and the unknown bent HCNC on the hypersurface of neutral, anionic, and cationic species, where the barriers are feasible.…”

Section: -16mentioning

confidence: 99%

Theoretical Study on the Reaction Mechanism of Azacyclopropenylidene with Epoxypropane: An Insertion Process

Tan¹,

Li²

2014

Bulletin of the Korean Chemical Society

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The reaction mechanism between azacyclopropenylidene and epoxypropane has been systematically investigated employing the second-order Møller-Plesset perturbation theory (MP2) method to better understand the reactivity of azacyclopropenylidene with four-membered ring compound epoxypropane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. It was found that for the first step of this reaction, azacyclopropenylidene can insert into epoxypropane at its C-O or C-C bond to form spiro intermediate IM. It is easier for the azacyclopropenylidene to insert into the C-O bond than the C-C bond. Through the ring-opened step at the C-C bond of azacyclopropenylidene fragment, IM can transfer to product P1, which is named as pathway (1). On the other hand, through the H-transferred step and subsequent ring-opened step at the C-N bond of azacyclopropenylidene fragment, IM can convert to product P2, which is named as pathway (2). From the thermodynamics viewpoint, the P2 characterized by an allene is the dominating product. From the kinetic viewpoint, the pathway (1) of formation to P1 is primary.

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Halogen switching of azacarbenes C₂NH ground states at ab initio and DFT levels

Abstract: ABSTRACT:Relative stabilities and singlet-triplet energy differences are calculated for 24 C

Cited by 23 publications

References 99 publications

Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Insights Into the Reaction Mechanism Between Azacyclopropenylidene and Azacyclopropane: A Theoretical Study

Theoretical Study on the Reaction Mechanism of Azacyclopropenylidene with Epoxypropane: An Insertion Process

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Halogen switching of azacarbenes C2NH ground states at ab initio and DFT levels

Abstract: ABSTRACT:Relative stabilities and singlet-triplet energy differences are calculated for 24 C

Cited by 23 publications

References 99 publications

Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Accurate ab initio quartic force fields of cyclic and bent HC2N isomers

Insights Into the Reaction Mechanism Between Azacyclopropenylidene and Azacyclopropane: A Theoretical Study

Theoretical Study on the Reaction Mechanism of Azacyclopropenylidene with Epoxypropane: An Insertion Process

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Product

Resources

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Halogen switching of azacarbenes C₂NH ground states at ab initio and DFT levels