scholarly journals On the elusive anti-bayerite structure

2020 ◽  
Author(s):  
Georgios S.E. Antipas
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonds ◽  
Charge Density ◽  
Density Functional ◽  
Hydration Shell ◽  
Isomer Ratio ◽  
Energy Decomposition ◽  
Functional Theory ◽  
Deformation Density ◽  
A Charge

Sequential deprotonation of the Cr3+ hexahydrate in an alkaline environment up to the stage of a charge-neutral active hydroxide was studied via density functional theory. The deprotonation could be characterized as autocatalytic since upon completion of every H-abstraction stage, Cr was found to mediate O-H dissociation in the next stage by pre-conditioning the ligand O atom that contributes the highest 2s density into Cr-4s based molecular orbitals; the latter amounts to a greater Cr-O distance due to increased charge density along the Cr-O axis. A direct effect of such Cr-4s/O-2s mixing is the reduction of electronegativity of the ligand-O atom and a corresponding high Voronoi deformation density (VDD) of the attached ligand-H atoms. Based on bonding energy decomposition, a facial to meridional isomer ratio of between 2:1 and 3:1 was derived as the most probable stereochemical mix of the active hydroxide; the latter forms, by mutual donation and acceptance, six hydrogen bonds with second hydration shell molecules.

Displacement parameters from density-functional theory and their validation in the experimental charge density of tartaric acid

CrystEngComm ◽  
2021 ◽  
Author(s):  
Damian Mroz ◽  
Ruimin Wang ◽  
Ulli Englert ◽  
Richard Dronskowski
Keyword(s):  
Density Functional Theory ◽  
Charge Density ◽  
Tartaric Acid ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Functional Theory ◽  
Anisotropic Displacement Parameters ◽  
A Charge ◽  
Density Study ◽  
Experimental Charge Density

Advanced theory matches advanced experiment: anisotropic displacement parameters for tartaric acid have been calculated in the quasi-harmonic approximation and determined experimentally based on a charge density study.

scholarly journals Solvatochromism and Theoretical Studies of Dicyanobis(phenylpyridine)iridium(III) Complex Using Density Functional Theory

2021 ◽  
Vol 21 (3) ◽  
pp. 769
Author(s):  
Noorshida Mohd Ali ◽  
Anthony J. H. M. Meijer ◽  
Michael D. Ward ◽  
Norlinda Daud ◽  
Norhayati Hashim ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Good Description ◽  
Photophysical Properties ◽  
Hydration Shell ◽  
Water Molecules ◽  
Singlet Ground State ◽  
Absorption Bands ◽  
Functional Theory

Luminescent cyanometallate [Ir(ppy)2(CN)2]– (ppy = C6H5C5H4N) has recently gained attention due to its desired photophysical properties. Our research group reported that the [Ir(ppy)2(CN)2]– has shown a negative solvatochromism like [Ru(bipy)(CN)4]2–, resulting in a blue-shift of the UV-Vis absorption bands in the water. Therefore, to gain insight into the specific solvent-solute interaction governed by the hydrogen bond in the solvation hydration shell, density functional theory (DFT) calculations were performed on the singlet ground state of the [Ir(ppy)2(CN)2]– and its solvent environment in the water at B3LYP level theory. It was demonstrated, seven water molecules provided a good description of the relevant spectra: IR and UV-Vis. The calculation reproduced the positions and intensities of the observed n(CºN) bands at 2069 and 2089 cm–1. The calculated MLCT transition wavelength was 366 nm vs. a measured value of 358 nm, differing by 8 nm. The study revealed the water molecules interacted with cyanide ligands through CN⋯H-OH type hydrogen bonds and water-water interactions (HO-H⋯OH2 type hydrogen bonds) were involved in the solvation hydration shell around the [Ir(ppy)2(CN)2]–.

scholarly journals Spectroscopic, X-ray Diffraction and Density Functional Theory Study of Intra- and Intermolecular Hydrogen Bonds in Ortho-(4-tolylsulfonamido)benzamides

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 926
Author(s):  
Malose J. Mphahlele ◽  
Eugene E. Onwu ◽  
Marole M. Maluleka
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Tetrahedral Geometry ◽  
Hindered Rotation ◽  
Hydrogen Bond Acceptor ◽  
Functional Theory ◽  
Vis Spectroscopy ◽  
Hydrogen Bonded

The conformations of the title compounds were determined in solution (NMR and UV-Vis spectroscopy) and in the solid state (FT-IR and XRD), complemented with density functional theory (DFT) in the gas phase. The nonequivalence of the amide protons of these compounds due to the hindered rotation of the C(O)–NH2 single bond resulted in two distinct resonances of different chemical shift values in the aromatic region of their 1H-NMR spectra. Intramolecular hydrogen bonding interactions between the carbonyl oxygen and the sulfonamide hydrogen atom were observed in the solution phase and solid state. XRD confirmed the ability of the amide moiety of this class of compounds to function as a hydrogen bond acceptor to form a six-membered hydrogen bonded ring and a donor simultaneously to form intermolecular hydrogen bonded complexes of the type N–H···O=S. The distorted tetrahedral geometry of the sulfur atom resulted in a deviation of the sulfonamide moiety from co-planarity of the anthranilamide scaffold, and this geometry enabled oxygen atoms to form hydrogen bonds in higher dimensions.

scholarly journals Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

2015 ◽  
Vol 11 ◽  
pp. 2727-2736 ◽  
Author(s):  
Diego M Andrada ◽  
Nicole Holzmann ◽  
Thomas Hamadi ◽  
Gernot Frenking
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Heterocyclic Carbenes ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Direct Estimate ◽  
Functional Theory ◽  
Bonding Analysis

Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.

6-Bromoindigo dye

2012 ◽  
Vol 68 (4) ◽  
pp. o160-o163 ◽  
Author(s):  
David J. Szalda ◽  
Keith Ramig ◽  
Olga Lavinda ◽  
Zvi C. Koren ◽  
Lou Massa
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Stacking Interactions ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Functional Theory ◽  
Bond Lengths ◽  
Type C

6-Bromoindigo (MBI) [systematic name: 6-bromo-2-(3-oxo-2,3-dihydro-1H-indol-2-ylidene)-2,3-dihydro-1H-indol-3-one], C16H9BrN2O2, crystallizes with one disordered molecule in the asymmetric unit about a pseudo-inversion center, as shown by the Br-atom disorder of 0.682 (3):0.318 (3). The 18 indigo ring atoms occupy two sites which are displaced by 0.34 Å from each other as a result of this packing disorder. This difference in occupancy factors results in each atom in the reported model used to represent the two disordered sites being 0.08 Å from the higher-occupancy site and 0.26 Å from the lower-occupancy site. Thus, as a result of the disorder, the C—Br bond lengths in the disordered components are 0.08 and 0.26 Å shorter than those found in 6,6′-dibromoindigo (DBI) [Süsse & Krampe (1979).Naturwissenschaften,66, 110], although the distances within the indigo ring are similar to those found in DBI. The crystals are also twinned by merohedry. Stacking interactions and hydrogen bonds are similar to those found in the structures of indigo and DBI. In MBI, an interaction of the type C—Br...C replaces the C—Br...Br interactions found in DBI. The interactions in MBI were calculated quantum mechanically using density functional theory and the quantum theory of atoms in molecules.

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