Role of Spin−Orbit Coupling and Symmetry in Triplet Carbenic Addition Chemistry

Su, Ming‐Der

doi:10.1021/jp950290j

Cited by 41 publications

(31 citation statements)

References 73 publications

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“…The B3LYP computational normal modes associated with the single imaginary frequency are consistent with the C〓N activation process, primarily the C〓N bond stretching with the migration of an E atom to the double bond. It should be noted that these characteristic three-centered cyclic transition states are quite analogous to the mechanisms observed for the cycloaddition reactions of singlet carbenes [64].…”

Section: Geometries and Energetics Of 7-rea-e+ Phhc〓nphsupporting

confidence: 58%

Theoretical Investigations of Mechanisms for the Reactions of Seven-Member Ring N-Heterocyclic Carbene and Its Heavier Analogues

Liu¹,

Su²

2018

Chemical Reactions in Inorganic Chemistry

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The potential energy surfaces for the chemical reactions of group 14 carbenes were studied using density functional theory (B3LYP/LANL2DZ + dp). Five group 14 carbene species containing a seven-member ring, 7-Rea-E, where E = C, Si, Ge, Sn and Pb, were chosen as model reactants for this work. Three types of chemical reactions (water addition, imine cycloaddition and dimerization) were used to study the reactivity of these 7-Rea-E molecules. Present theoretical investigations suggest that the relative reactivity of carbenes decreases in the order: 7-Rea-C > 7-Rea-Si > 7-Rea-Ge > 7-Rea-Sn > 7-Rea-Pb. That is, the heavier the group 14 atom (E), the more stable its corresponding 7-Rea-E compound to chemical reaction. This study's theoretical findings suggest that all of the seven-member 7-Rea-E should be readily synthesized and isolated at room temperature, since they are quite inert to chemical reaction, except for reaction with moisture. Furthermore, the group 14 7-Rea-E singlet-triplet energy splitting, as described in the configuration-mixing model of Pross and Shaik, can be used as a diagnostic tool to predict their reactivity. The results obtained allow a number of predictions to be made.

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Section: Geometries and Energetics Of 7-rea-e+ Phhc〓nphsupporting

confidence: 58%

Theoretical Investigations of Mechanisms for the Reactions of Seven-Member Ring N-Heterocyclic Carbene and Its Heavier Analogues

Liu¹,

Su²

2018

Chemical Reactions in Inorganic Chemistry

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“…Their normal modes associated with the single imaginary frequency are consistent with the CC activation process, primarily the CC bond stretching with a group 14 E atom migrating to the double bond. It has to be mentioned that such characteristic three‐centered cyclic transition states are quite analogous to mechanisms observed for the addition reactions of singlet carbene 17…”

Section: Resultsmentioning

confidence: 57%

A computational study of the reactivities of four‐membered heavy carbene systems

Wu¹,

Su²

2011

J Comput Chem

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The potential energy surfaces for the chemical reactions of four-membered N-heterocyclic group 14 heavy carbene species have been studied using density functional theory (B3LYP/LANL2DZ). Five four-membered group 14 heavy carbene species, (i-Pr)(2) NP(NR)(2) E:, in which E = C, Si, Ge, Sn, and Pb, were chosen as the model reactants in this work. Also, four kinds of chemical reactions, C-H bond insertion, water addition, alkene cycloaddition, and dimerization, have been used to study the chemical reactivities of these group 14 four-membered N-heterocyclic carbene species. Basically, our present theoretical work predicts that the larger the ∠NEN bond angle of the four-membered group 14 heavy carbene species, the smaller the singlet-triplet splitting, the lower the activation barrier, and, in turn, the more rapid, its chemical reactions to various chemical species. Moreover, our theoretical investigations suggest that the relative carbenic reactivity decreases in the order: C > Si > Ge > Sn > Pb. That is, the heavier the group 14 atom (E), the more stable is its four-membered carbene toward chemical reactions. As a result, our results predict that the four-membered group 14 heavy carbene species (E = Si, Ge, Sn, and Pb) should be more kinetically stable than the observed carbene species and, thus, can be also readily synthesized and isolated at room temperature. Furthermore, the singlet-triplet energy splitting of the four-membered group 14 carbene species, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made.

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“…A very clear discussion about SOC in molecules has been provided by McGlynn, 14 Shaik, Epiotis 15,16 and Ming-Der Su et al 17 They have shown that the probability for such a spin inversion process to occur is directly proportional to the SOC matrix element 1 …”

Section: Spin-orbit Coupling Matrix Elementsmentioning

confidence: 99%

Spin‐orbit Coupling and Intersystem Crossing in 4H‐Pyran‐4‐thione: CASSCF//TD‐B3LYP Study

Lu¹,

Liu

Yuan

et al. 2007

Chin. J. Chem.

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The intersystem crossing channels of gaseous 4H-pyran-4-thione were investigated using the CASSCF//TD-B3LYP methods and group theory. Using the effective one-electron spin-orbit Hamiltonian, the strengths of spin-orbit coupling were estimated, which plays an essential role in the spin transitions between different spin states. Calculated results show that phosphorescence and non-radiative decay via intersystem crossing to the S 0 state are concurrent processes occurring at the T 1 state. A rapid depletion of the S 1 state via intersystem crossing to the T 1 state can be mediated by the T 2 state, if spin relaxation is fast within the triplet levels. Our calculated results are in close agreement with experimental observations.

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Role of Spin−Orbit Coupling and Symmetry in Triplet Carbenic Addition Chemistry

Cited by 41 publications

References 73 publications

Theoretical Investigations of Mechanisms for the Reactions of Seven-Member Ring N-Heterocyclic Carbene and Its Heavier Analogues

Theoretical Investigations of Mechanisms for the Reactions of Seven-Member Ring N-Heterocyclic Carbene and Its Heavier Analogues

A computational study of the reactivities of four‐membered heavy carbene systems

Spin‐orbit Coupling and Intersystem Crossing in 4H‐Pyran‐4‐thione: CASSCF//TD‐B3LYP Study

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