scholarly journals Revisiting the Electronic Structure of Cobalt Porphyrin Nitrene and Carbene Radicals with NEVPT2-CASSCF Calculations: Doublet versus Quartet Ground States

2021 ◽  
Author(s):  
Nicolaas P. van Leest ◽  
Bas de Bruin
Keyword(s):  
Electronic Structure ◽  
Ground States ◽  
Cobalt Porphyrin

scholarly journals Many-body electronic structure and Kondo properties of cobalt-porphyrin molecules

2009 ◽  
Vol 80 (15) ◽  
Author(s):  
Luis G. G. V. Dias da Silva ◽  
Murilo L. Tiago ◽  
Sergio E. Ulloa ◽  
Fernando A. Reboredo ◽  
Elbio Dagotto
Keyword(s):  
Electronic Structure ◽  
Many Body ◽  
Cobalt Porphyrin

Valence-bond studies of 4-electron 3-centre bonding units. I. The π-electrons of O3, NO2−, and CH2N2

1978 ◽  
Vol 56 (8) ◽  
pp. 1093-1101 ◽  
Author(s):  
Richard D. Harcourt ◽  
Walter Roso
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Valence Bond ◽  
Ground States ◽  
Wave Functions ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Electronic Mechanism ◽  
Increased Valence

Some ab-initio valence-bond wave-functions are reported for the π-electrons of the ground-states of O3, NO2−, and CH2N2. Examination of these wave-functions provides further support for the hypothesis that, for the ground-states of many electron-excess molecules, important valence-bond structures are those that are compatible with the electroneutrality principle, i.e. they carry either small or zero formal charges on each of the atoms. For O3 and CH2N2, the important valence-bond structures with zero atomic formal charges are [Formula: see text]Each of these structures has a 'long-bond' between non-adjacent atoms. The significance of 'long-bond' (or spin-paired diradical) structures for the electronic mechanism of 1,3-dipolar cycloaddition reactions is discussed and 'increased-valence' descriptions of the electronic structure of each molecule are presented. Some comments on the utility of 'increased-valence' structures are provided.

scholarly journals Revisiting the Electronic Structure of Cobalt-Porphyrin Nitrene and Carbene Radicals with NEVPT2-CASSCF Calculations: Doublet versus Quartet Ground States

2021 ◽  
Author(s):  
Nicolaas P. van Leest ◽  
Bas de Bruin
Keyword(s):  
Ground State ◽  
Ground States ◽  
Broken Symmetry ◽  
Transfer Reactions ◽  
Group Transfer ◽  
Cobalt Porphyrin ◽  
Spin Counting ◽  
State Wavefunctions ◽  
Radical Character ◽  
Spin Ground State

Cobalt-porphyrin complexes are established catalysts for carbene and nitrene radical group transfer reactions. The key carbene, mono- and bis-nitrene radical complexes coordinated to [Co(TPP)] (TPP = tetraphenylporphyrin) have previously been investigat-ed with a variety of experimental techniques and supporting (single-reference) DFT calculations that indicated doublet (S = ½) ground states for all three species. In this contribution we revisit their electronic structures with multireference NEVPT2-CASSCF calculations to investigate possible multireference contributions to the ground state wavefunctions. The carbene ([Co<sup>III</sup>(TPP)(•CHCO<sub>2</sub>Et)]) and mono-nitrene ([Co<sup>III</sup>(TPP)(•NNs)]) radical complexes were confirmed to have uncomplicated doublet ground states, although a higher carbene or nitrene radical character and a lower Co‒C/N bond order was found in the NEVPT2-CASSCF calculations. Supported by EPR analysis and spin counting, paramagnetic molar susceptibility determination and NEVPT2-CASSCF calculations, we report that the cobalt-porphyrin bis-nitrene complex ([Co<sup>III</sup>(TPP•)(•NNs)<sub>2</sub>]) has a quartet (S = 3/2) spin ground state, with a thermally assessable multireference & multideterminant ‘broken-symmetry’ doublet spin excited state. A spin flip on the porphyrin-centered unpaired electron allows for interconversion between the quartet and broken-symmetry doublet spin states, with an approximate 10- and 200-fold higher Boltzmann population of the quartet at room tempera-ture or 10 K, respectively.<br>

Ab initio calculations of the electronic structure of the ground states of HBeHe+ and BeHe22+

2007 ◽  
Vol 442 (4-6) ◽  
pp. 194-200 ◽  
Author(s):  
Alister J. Page ◽  
David J.D. Wilson ◽  
Ellak I. von Nagy-Felsobuki
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Ground States

Electronic structure and magnetic properties of the triangular nanographenes with radical substituents: a DFT study

2020 ◽  
Vol 22 (3) ◽  
pp. 1288-1298
Author(s):  
Vladimir I. Minkin ◽  
Andrey G. Starikov ◽  
Alyona A. Starikova ◽  
Olga A. Gapurenko ◽  
Ruslan M. Minyaev ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Ground States ◽  
Dft Study ◽  
Polycyclic Hydrocarbons ◽  
Dft Modeling ◽  
Structural Peculiarities ◽  
Electronic Ground

DFT modeling of triangular polycyclic hydrocarbons bearing radicals provided insights into dependence of electronic ground states on their structural peculiarities

Electronic structure of CNa and CNa2 in their electronic ground states

1984 ◽  
Vol 88 (21) ◽  
pp. 4973-4978 ◽  
Author(s):  
Aristides Mavridis ◽  
James F. Harrison ◽  
Joel F. Liebman
Keyword(s):  
Electronic Structure ◽  
Ground States ◽  
Electronic Ground

Electronic Structure of the Transition Elements

1973 ◽  
Vol 51 (6) ◽  
pp. 644-647
Author(s):  
K. M. S. Saxena ◽  
S. Fraga
Keyword(s):  
Electronic Structure ◽  
Excited States ◽  
Ground State ◽  
Ground States ◽  
Negative Ions ◽  
State Function ◽  
Transition Elements ◽  
Hartree Fock ◽  
Positive Ions ◽  
Single Set

Numerical Hartree–Fock functions have been determined for the ground states and first excited states of the configurations 3dN4s0 and 3dN4s2 for the negative ions, neutral atoms, and first four positive ions of all the transition elements. The validity of the approximation, embodied in the use of a single set of parameters determined from the ground state function of a configuration for the prediction of the spectroscopic levels arising from it, has been examined in detail in the case of Fe I, 3d64s2, where independent calculations have been carried out for all the excited states.

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