The Ionic Character of Diatomic Molecules

Dailey, B. P.; Townes, C. H.

doi:10.1063/1.1740508

Cited by 304 publications

(47 citation statements)

References 11 publications

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“…For atomic chlorine, eQq has been previously determined to be À109.74 MHz [16] and is a measure of the atom's valence state 3s 2 3p 5 [16]. In the simplest interpretation, a covalently-bonded molecule will maintain this valence state and therefore have an eQq value similar to that of atomic chlorine [15][16][17][18].…”

Section: Discussionmentioning

confidence: 96%

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The sub-millimeter and Fourier transform microwave spectrum of HZnCl (X 1Σ+)

Pulliam

Sun

Flory

et al. 2009

Journal of Molecular Spectroscopy

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Section: Discussionmentioning

confidence: 96%

“…This difference suggests that the species is primarily ionic in nature. Using the Townes and Dailey approximation, the fraction of ionic character x in this molecule can be estimated from the following equation [15][16][17]:…”

Section: Discussionmentioning

confidence: 99%

The sub-millimeter and Fourier transform microwave spectrum of HZnCl (X 1Σ+)

Pulliam

Sun

Flory

et al. 2009

Journal of Molecular Spectroscopy

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“…Instead of specifying two of the principal components, one may also characterize the tensor by V 33 , its largest magnitude principal component, and the asymmetry parameter η Q = (V 11 − V 22 )/V 33 , where η Q (or simply η, as the asymmetry parameters for the EFG and the quadrupole tensor are the same) takes on values only from 0 to 1. The latter describes the symmetry of the EFG tensor.…”

Section: The Quadrupolar Interaction the Electric Field Gradientmentioning

confidence: 99%

Analysis of electric field gradient tensors at quadrupolar nuclei in common structural motifs

Autschbach¹,

Zheng²,

Schurko³

2010

Concepts Magnetic Resonance

167

259

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ABSTRACT:This article is concerned with the analysis of electric field gradients (EFGs) using first-principles theory along with model calculations. Simple atomic orbital (AO) models for the EFG are developed in the spirit of the Townes-Dailey (TD) analysis and applied to various sets of sp n hybrid orbitals and to atomic d orbital shells. These AO models are then combined with modern analysis methods rooted in first principles theory which provide accurate localized molecular orbital contributions to the EFG. It is shown by density functional computations how such analyses of the EFG for a variety of typical structural motifs can provide an intuitive way of understanding the chemical origin of the magnitude and the sign of EFG tensors at atomic nuclei, as well as of their orientation with respect to the molecular coordinate frame. The utility of graphical visualizations of EFG tensors is also emphasized. The systems that are investigated span the range from very small molecules (carbon and sulfur EFGs in CO, CS, OCS) to small-and medium-sized molecules (nitrogen and aluminum EFGs in ammonia, methyl-cyanide and -isocyanide, aluminum AlX 3 model systems and various alumino-organic systems), to the metal atom field gradient in transition metal complexes with Ru and Nb and a variety of ligands.

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“…Townes et al [34][35][36] have developed a semi-quantitative model relating experimentally measured quadrupole parameters of diatomic molecules to the degree of ionic or hybrid character of the bond. The model assumes that only p-like orbitals contribute to the observed electric field gradient at the nucleus in question, so a simple molecular orbital picture of the A 2 P state of CN would predict a 14 N quadrupole coupling constant of (1/4)eQq 210 [36].…”

Section: Parametermentioning

confidence: 99%