Experimental Charge Density and Neutron Structural Study ofcis-HMn(CO)4PPh3:  Comprehensive Analysis of Chemical Bonding and Evidence for a C−H···H−Mn Hydrogen Bond

1998 ◽  
Vol 37 (24) ◽  
pp. 6317-6328 ◽  
Author(s):  
Yuriy A. Abramov ◽  
Lee Brammer ◽  
Wim T. Klooster ◽  
R. Morris Bullock
Keyword(s):  
Hydrogen Bond ◽  
Charge Density ◽  
Structural Study ◽  
Chemical Bonding ◽  
Comprehensive Analysis ◽  
Experimental Charge Density

scholarly journals Synchrotron charge density studies of chemical bonding in the polymorphs of FeS2

2014 ◽  
Vol 70 (a1) ◽  
pp. C1338-C1338
Author(s):  
Jacob Overgaard ◽  
Mette Schmøkel ◽  
Lasse Bjerg ◽  
Simone Cenedese ◽  
Mads Jørgensen ◽  
...  
Keyword(s):  
Charge Density ◽  
Chemical Bonding ◽  
Negative Energy ◽  
X Ray Diffraction ◽  
Crystal Field Theory ◽  
Covalent Bonds ◽  
Density Distributions ◽  
Synchrotron Studies ◽  
Experimental Charge Density ◽  
Periodic Calculations

The experimental charge density (CD) distributions in both polymorphs of the photovoltaic compound iron-disulphide (FeS2; cubic pyrite and orthorhombic marcasite) will be described.[1] The CDs are determined by multipole modelling using synchrotron X-ray diffraction data collected at 10 K on extremely small single crystals (<10 mu) thus minimizing the influence of systematic errors such as absorption, extinction and TDS, and exploiting experiences gained from our recent synchrotron studies of CoSb3.[2] The analysis of the charge density in both polymorphs of FeS2 provides an opportunity to see how the different geometries affect local atomic properties, such as 2-center chemical bonding, atomic charges and d-orbital populations. In particular, the data and the resulting multipole models enable us to link the atomic-centered view that emerges from the multipole analysis with the band structure approach. This is carried out by combination with results from periodic calculations on the compounds in the experimental geometries using WIEN2k, thereby providing unambiguous answers to a number of unsolved issues regarding the nature of the bonding in FeS2. The chemical bonding will be characterized by topological analyses showing that the Fe-S bonds are polar covalent bonds, with only minor charge accumulation but significantly negative energy densities at the bond critical points. Using the IAM as reference, density is found to accumulate in-between the atoms, supporting a partial covalent bonding description. The homopolar covalent S-S interaction is seemingly stronger in pyrite than in marcasite, determined not only from the shorter distance but also from all topological indicators. Integrated atomic (Bader) charges show significantly smaller values than those estimation based on crystal-field theory of Fe2+, S-1. In connection with this, the experimentally derived d-orbital populations on Fe are found to deviate from the commonly assumed full t2g set, empty eg set, and they fit very well with the theoretical individual atomic orbitals projected density of states showing a higher dxy participation in the valence band in marcasite compared with pyrite. Thus, the differences between the two polymorphic compounds are directly reflected in their valence density distributions and d-orbital populations.

Is there a future for topological analysis in experimental charge-density research?

2017 ◽  
Vol 73 (3) ◽  
pp. 325-329 ◽  
Author(s):  
Birger Dittrich
Keyword(s):  
Charge Density ◽  
Intermolecular Interaction ◽  
Intermolecular Interactions ◽  
Chemical Bonding ◽  
Topological Analysis ◽  
Theoretical Chemistry ◽  
Research Tool ◽  
Interaction Energies ◽  
Research Focus ◽  
Experimental Charge Density

Topological analysis using Bader and co-worker'sAtoms in Moleculestheory has seen many applications in theoretical chemistry and experimental charge-density research. A brief overview of successful early developments, establishing topological analysis as a research tool for characterizing intramolecular chemical bonding, is provided. A lack of vision in many `descriptive but not predictive' subsequent studies is discussed. Limitations of topology for providing accurate energetic estimates of intermolecular interaction energies are put into perspective. It is recommended that topological analyses of well understood bonding situations are phased out and are only reported for unusual bonding. Descriptive studies of intermolecular interactions should have a clear research focus.

Experimental charge density of an L-phenylalanine formic acid complex with a short hydrogen bond determined at 25 K

2006 ◽  
Vol 221 (9) ◽  
Author(s):  
Stefan Mebs ◽  
Marc Messerschmidt ◽  
Peter Luger
Keyword(s):  
Hydrogen Bond ◽  
High Resolution ◽  
Formic Acid ◽  
Charge Density ◽  
Topological Properties ◽  
Acid Complex ◽  
Data Set ◽  
X Ray ◽  
Short Hydrogen Bond ◽  
Experimental Charge Density

AbstractThe experimental charge density and related atomic and bond topological properties of an L-phenylalanine formic acid complex were derived from a high resolution X-ray data set (sin θ/λ = 1.18 Å

Anion effect on alkali ion-crown complex formation in a moderately concentrated solutions: A sensitive probe of hidden interionic interactions operating in dissociating protic solvents

1990 ◽  
Vol 55 (5) ◽  
pp. 1149-1161
Author(s):  
Jiří Závada ◽  
Václav Pechanec ◽  
Oldřich Kocián
Keyword(s):  
Hydrogen Bond ◽  
Complex Formation ◽  
Charge Density ◽  
Macrocyclic Ligand ◽  
Simple Explanation ◽  
Anion Effect ◽  
Protic Solvents ◽  
The Individual ◽  
Alkali Salts ◽  
Alkali Ion

A powerful anion effect destabilizing alkali ion-crown complex formation has been found to operate in moderately concentrated protic (H2O, CH3OH, C2H5OH) solution, following the order HO- > AcO- > Cl- > Br- > NO3- > I- > NCS-. Evidence is provided that the observed effect does not originate from ion-pairing. A simple explanation is provided in terms of concordant hydrogen bond bridges of exalted stability between the gegenions, M+···OR-H···(OR-H)n···OR-H···A-. It is proposed that encapsulation of alkali ion by the macrocyclic ligand leads to a dissipation of the cation charge density destroying its ability to participate in the hydrogen bond bridge. An opposition against the alkali ion-crown complex formation arises accordingly in the solution in dependence on strength of the hydrogen bridge; for a given cation, the hydrogen bond strength increases with increasing anion charge density from NCS- to HO-(RO-). It is pointed out, at the same time, that the observed anion effect does not correlate with the known values of activity coefficients of the individual alkali salts which are almost insensitive to anion variation under the investigated conditions. As a resolution of the apparent paradoxon it is proposed that, in absence of the macrocyclic ligand, the stabilizing (concordant) bonding between the gegenions is nearly balanced by a destabilizing (discordant) hydrogen bonding between the ions of same charge (co-ions). Intrinsic differences among the individual salts are thus submerged in protic solvents and become apparent only when the concordant bonding is suppressed in the alkali ion-crown complex formation.

scholarly journals Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge2Sb2Te5

RSC Advances ◽  
2021 ◽  
Vol 11 (36) ◽  
pp. 22479-22488
Author(s):  
Jeong Hwa Han ◽  
Hun Jeong ◽  
Hanjin Park ◽  
Hoedon Kwon ◽  
Dasol Kim ◽  
...  
Keyword(s):  
Phase Change ◽  
Charge Density ◽  
Chemical Bonding ◽  
Local Structure ◽  
Phase Change Memory ◽  
Change Memory

Charge density differences (CDDs) on Ge–C–Sb bonds in CGST(5%) and Ge–C–Sb in CGST(10%).

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

Characterization of the B⋯π-system interaction via topology of the experimental charge density distribution in the crystal of 3-chloro-7α-phenyl-3-borabicyclo[3.3.1]nonane

2004 ◽  
Vol 384 (1-3) ◽  
pp. 40-44 ◽  
Author(s):  
Konstatin A Lyssenko ◽  
Mikhail Yu Antipin ◽  
Mikhail E Gurskii ◽  
Yurii N Bubnov ◽  
Anna L Karionova ◽  
...  
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Charge Density Distribution ◽  
Experimental Charge Density
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