scholarly journals Relationship of QTAIM and NOCV Descriptors with Tolman’s Electronic Parameter

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Tímea R. Kégl ◽  
László Kollár ◽  
Tamás Kégl
Keyword(s):  
Critical Point ◽  
Electron Density ◽  
Donor Ligands ◽  
Bond Critical Point ◽  
Energy Component ◽  
Bond Index ◽  
Electronic Parameter ◽  
Deformation Density ◽  
Electronic Parameters ◽  
Relationship Of

The σ-donor properties of various P-donor ligands have been studied at the PBEPBE level of theory, which has proved to be accurate in computing the symmetric carbonyl stretching frequencies in nickel(0)-tricarbonyl complexes containing P-donor ligands. The delocalization index from the QTAIM methodology and the energy component associated with the NOCV deformation density representing the donor interaction give the best correlation with Tolman’s electronic parameters, whereas the electron density at the bond critical point and the Wiberg bond index are connected with the donor strength of the ligands to a lesser extent.

Bond length and the electron density at the bond critical point: XX, ZZ, and CZ bonds (X = Li-F, Z = Na-Cl)

2007 ◽  
Vol 29 (3) ◽  
pp. 367-379 ◽  
Author(s):  
Norberto Castillo ◽  
Katherine N. Robertson ◽  
S. C. Choi ◽  
Russell J. Boyd ◽  
Osvald Knop
Keyword(s):  
Bond Length ◽  
Critical Point ◽  
Electron Density ◽  
Bond Critical Point

Experimental observation of charge-shift bond in fluorite CaF2

2017 ◽  
Vol 73 (4) ◽  
pp. 643-653 ◽  
Author(s):  
Marcin Stachowicz ◽  
Maura Malinska ◽  
Jan Parafiniuk ◽  
Krzysztof Woźniak
Keyword(s):  
Quantum Theory ◽  
Density Distribution ◽  
Critical Point ◽  
Electron Density ◽  
Closed Shell ◽  
Atoms In Molecules ◽  
Bond Critical Point ◽  
Ionic Radii ◽  
Bond Path ◽  
Charge Shift

On the basis of a multipole refinement of single-crystal X-ray diffraction data collected using an Ag source at 90 K to a resolution of 1.63 Å−1, a quantitative experimental charge density distribution has been obtained for fluorite (CaF2). The atoms-in-molecules integrated experimental charges for Ca2+and F−ions are +1.40 e and −0.70 e, respectively. The derived electron-density distribution, maximum electron-density paths, interaction lines and bond critical points along Ca2+...F−and F−...F−contacts revealed the character of these interactions. The Ca2+...F−interaction is clearly a closed shell and ionic in character. However, the F−...F−interaction has properties associated with the recently recognized type of interaction referred to as `charge-shift' bonding. This conclusion is supported by the topology of the electron localization function and analysis of the quantum theory of atoms in molecules and crystals topological parameters. The Ca2+...F−bonded radii – measured as distances from the centre of the ion to the critical point – are 1.21 Å for the Ca2+cation and 1.15 Å for the F−anion. These values are in a good agreement with the corresponding Shannon ionic radii. The F−...F−bond path and bond critical point is also found in the CaF2crystal structure. According to the quantum theory of atoms in molecules and crystals, this interaction is attractive in character. This is additionally supported by the topology of non-covalent interactions based on the reduced density gradient.

SiO and GeO bonded interactions as inferred from the bond critical point properties of electron density distributions

1998 ◽  
Vol 25 (8) ◽  
pp. 574-584 ◽  
Author(s):  
G. V. Gibbs ◽  
M. B. Boisen ◽  
F. C. Hill ◽  
O. Tamada ◽  
R. T. Downs
Keyword(s):  
Critical Point ◽  
Electron Density ◽  
Bond Critical Point ◽  
Density Distributions

How does the geometry of the tetrahedral XF4−nClnε (X = Al, Si, P) species depend on composition, or abinitiosicertumnescio

1987 ◽  
Vol 65 (5) ◽  
pp. 1109-1123 ◽  
Author(s):  
S. C. Choi ◽  
Russell J. Boyd ◽  
Osvald Knop
Keyword(s):  
Critical Point ◽  
Electron Density ◽  
Power Function ◽  
Oxidation State ◽  
Relative Position ◽  
Halogen Atom ◽  
Bond Critical Point ◽  
Bond Lengths ◽  
Complicated Manner ◽  
Abinitio Calculations

The molecular parameters of the isoelectronic tetrahedral species NaF43−, MgF42−, AlF4−nCln−, SiF4−nCln PF4−nCln+, SF42+, and ClF43+ have been investigated by abinitio calculations at the 6-31G* level. The bond lengths and the critical radii of X in XF4ε are found to decrease monotonically with the formal oxidation state m of X up to and including X = S but show an upturn at X = Cl. The relative position of the critical point in the X—F bond, rc(X)/(X—F), remains relatively constant for m = 1–3; for m = 4–6 the critical point moves gradually closer to X, but for m = 7 it shifts appreciably away from X. The increase in the electron density at the bond critical point of XF4ε (and probably also of XCl4ε) is represented reasonably closely by a power function amb. The effect of progressive replacement of F in XF4ε (X = Al, Si, P) by Cl on the bond lengths and angles depends on the sign of ε. For ε = −1, X—F and X—Cl decrease and FXF increases; for ε = 0 and 1, X—F and X—Cl increase and FXF decreases. These changes increase in magnitude, in their respective directions, with |ε|. Relationships between the bond lengths and the bond angles are described. The excess total electronic energies [Formula: see text] are negative for all three X; they are largest (and approximately symmetric with respect to n) for Al, smaller (and asymmetric) for P, and very small for Si. The amount of charge transferred from F or Cl to X varies in a complicated manner with m and n, and the rates of transfer of charge with «in an XF4−nClnε molecule are not the same for F and Cl. More than one unit of charge is transferred from a halogen atom to X in ClF43+ and PCl4+.

scholarly journals Electronic structure of two isostructural `paddle-wheel' complexes: a comparative study

2018 ◽  
Vol 74 (6) ◽  
pp. 681-692 ◽  
Author(s):  
Peter Herich ◽  
Lukáš Bučinský ◽  
Martin Breza ◽  
Marián Gall ◽  
Marek Fronc ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Critical Point ◽  
Electron Density ◽  
Metal Atom ◽  
Bond Critical Point ◽  
X Ray ◽  
Metal Interaction ◽  
Metal Metal ◽  
Coordination Bonds ◽  
Oxygen Atoms

The experimental electron density distribution in two isostructural and isomorphous complexes, tetrakis(μ2-acetato)diaquadicopper(II) [H2OCu(ac)2Cu(ac)2H2O] (I) and tetrakis(μ2-acetato)diaquadichromium(II), [H2OCr(ac)2Cr(ac)2H2O] (II), has been obtained from high-resolution X-ray diffraction data in order to shed light on the bonding properties in the compounds studied. It has been shown that from accurate X-ray data it is possible to discuss the bonding capability of the metal atom (Cu/Cr) and the ligands in these complexes. A comparison of results obtained from averaged and non-averaged X-ray data demonstrates that using the non-averaged data and introducing an anisotropic correction for secondary extinction errors provides a more detailed distribution of the electron density in the area of the metal atoms. In both complexes studied, the bonding of the acetate oxygen atom to the central metal atom is significantly affected by the formation of hydrogen bonds. The electron density and its Laplacian at the bond critical point of metal–oxygen coordination bonds for those oxygen atoms not involved in the intermolecular hydrogen bonds are approximately 10% larger compared with the case when oxygen atoms take part in hydrogen bonds with the neighboring water molecules. It is shown that metal–oxygen bonds in a quasi-equatorial plane are typical coordination bonds and differ significantly from the apical metal–oxygen bond. Metal–metal interaction with a small positive value of the electron density Laplacian at this bond critical point is mainly of electrostatic character. The metal–metal interaction is definitely not a bond according to the classical definition. Based on a search of the Cambridge Structural Database, it can be argued that there are four typical coordination bonds in the [CuO6] chromophore, similar to the four Cu—O coordination bonds in the basal plane of the CuO5 pyramid in one of the complexes under study.

Sign in / Sign up

Export Citation Format

Share Document