Magnetic Shielding Study of Bonding and Aromaticity in Corannulene and Coronene

Bonding and aromaticity in the bowl-shaped C5v and planar D5h geometries of corannulene and the planar D6h geometry of coronene are investigated using 3D isosurfaces and 2D contour plots of the isotropic magnetic shielding σiso(r) and, for planar geometries, of the out-of-plane component of the shielding tensor σzz(r). Corannulene and coronene both feature conjoined shielded “doughnuts” around a peripheral six-membered carbon ring, suggesting strong bonding interactions and aromatic stability; a deshielded region inside the hub ring of corannulene indicates that this ring is antiaromatic, more so in planar corannulene. The switch from the planar to the bowl-shaped geometry of corannulene is shown to enhance both bonding and the local aromaticities of the five- and six-membered rings; these factors, in addition to ring strain reduction, favour the bowl-shaped geometry. The most and least shielded bonds in both corannulene and coronene turn out to be the spoke and hub bonds, respectively. The higher π electron activity over spoke bonds in planar corannulene and coronene is supported by σzz(r) contour plots in planes 1 Å above the respective molecular planes; these findings about spoke bonds are somewhat unexpected, given that ring current studies indicate next to no currents over spoke bonds.

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Integration of Global Ring Currents Using the Ampére-Maxwell Law

Physical Chemistry Chemical Physics ◽

10.1039/d1cp05061c ◽

2021 ◽

Author(s):

Raphael Berger ◽

Maria Dimitrova ◽

Rinat Nasibullin ◽

Rashid R. Valiev ◽

Dage Sundholm

Keyword(s):

Ring Current ◽

Magnetic Shielding ◽

Ring Currents ◽

Shielding Tensor

Magnetically induced ring current are calculated from the magnetic shielding tensor by employing the Ampére-Maxwell law. The feasibility of the method is demonstrated by integrating the zz component of the...

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Magnetic out-of-plane component in MnAs/GaAs(001)

Applied Physics Letters ◽

10.1063/1.1615682 ◽

2003 ◽

Vol 83 (14) ◽

pp. 2850-2852 ◽

Cited By ~ 24

Author(s):

A. Ney ◽

T. Hesjedal ◽

C. Pampuch ◽

J. Mohanty ◽

A. K. Das ◽

...

Keyword(s):

Plane Component ◽

Out Of Plane

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Ab initio calculations of the antisymmetric components of the nuclear magnetic shielding tensor

Chemical Physics Letters ◽

10.1016/0009-2614(83)80791-x ◽

1983 ◽

Vol 94 (2) ◽

pp. 596-598

Author(s):

M Iwai

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Magnetic Shielding ◽

Shielding Tensor ◽

Nuclear Magnetic

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The Rotational Zeeman Effect in Fluorobenzene and the Molecular Quadrupole Moment in Benzene

Zeitschrift für Naturforschung A ◽

10.1515/zna-1982-1008 ◽

1982 ◽

Vol 37 (10) ◽

pp. 1165-1175 ◽

Cited By ~ 5

Author(s):

W. H. Stolze ◽

M. Stolze ◽

D. Hübner ◽

D. H. Sutter

Keyword(s):

Magnetic Susceptibility ◽

Carbon Tetrachloride ◽

Quadrupole Moment ◽

Ring Current ◽

Zeeman Effect ◽

Electric Quadrupole ◽

Quadrupole Moments ◽

Electric Quadrupole Moment ◽

Microwave Spectrometer ◽

Out Of Plane

The rotational Zeeman effect in fluorobenzene is reinvestigated with a resolution improved by a factor of almost five to give more accurate g-tensor elements, magnetic susceptibility anisotropics and molecular electric quadrupole moments. The results fit into the pictures of a linear dependence of the out of plane molecular electric quadrupole moment, Qcc, on the number of fluorine substituents and of a linear correlation between the nonlocal (ring current) susceptibility, Χccnonlocal, and the CNDO/2-π-electron density alternation. They lead to a gasphase molecular electric quadrupole moment in benzene, Qcc,benzene = - (28.4 ± 4.7) · 10-40 Cm2 which is slightly less negative than the value deduced from electric field-gradient birefringence experiments on dilute benzene solutions with carbon tetrachloride as solvent. A detailed description of the high resolution microwave spectrometer is given in the appendix.

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Probing solid iminobis(diorganophosphine chalcogenide) systems with multinuclear magnetic resonance

Canadian Journal of Chemistry ◽

10.1139/v08-150 ◽

2009 ◽

Vol 87 (1) ◽

pp. 348-360 ◽

Cited By ~ 1

Author(s):

Bryan A Demko ◽

Roderick E Wasylishen

Keyword(s):

Solid State ◽

Chemical Shift ◽

Solid State Nmr ◽

Magnetic Shielding ◽

Chemical Shift Tensors ◽

X Ray ◽

X Ray Crystallography ◽

Shielding Tensor ◽

Nuclear Magnetic Shielding Tensors ◽

Nuclear Magnetic

A 31P and 77Se solid-state NMR investigation of the iminobis(diorganophosphine chalcogenide) HN(R2PE)2 (R = Ph,iPr; E = O, S, Se) systems is presented. The NMR results are discussed in terms of the known HN(R2PE)2 structures available from X-ray crystallography. The phosphorus chemical shift tensors are found to be sensitive to the nature of the alkyl and chalcogen substituents. The nature of the R group also influences the selenium chemical shift tensors of HN(R2PSe)2 (R = Ph, iPr), which are shown to be sensitive to hydrogen bonding in the dimer structure of HN(Ph2PSe)2 and to the presence of disorder in the case of HN(iPr2PSe)2. Scalar relativistic ZORA DFT nuclear magnetic shielding tensor calculations were performed yielding the orientations of the corresponding chemical shift tensors. A theoretical investigation into the effect of the E-P···P-E “torsion” angle on the phosphorus and selenium chemical shift tensors of a truncated HN(Me2PSe)2 system indicates that the electronic effect of the alkyl group on the respective nuclear magnetic shielding tensors are more important than the steric effect of the E-P···P-E torsion angle.Key words: iminobis(diorganophosphine chalcogenide), solid-state NMR, 31P NMR, 77Se NMR, ZORA DFT.

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