scholarly journals Cubic Octa-Carbon: Quantum-Chemical Design of Molecular Structure and Potential Way of Its Synthesis from Cubane

2021 ◽  
Vol 22 (21) ◽  
pp. 12067
Author(s):  
Denis V. Chachkov ◽  
Oleg V. Mikhailov
Keyword(s):  
Quantum Chemical ◽  
Thermodynamic Characteristics ◽  
Structural Data ◽  
Analysis Data ◽  
Nbo Analysis ◽  
Chemical Calculation ◽  
Torsion Angles ◽  
Cubic Form ◽  
Quantum Chemical Methods ◽  
Short Time

Quantum-chemical calculation of most important parameters of molecular and electronic structures of octa-carbon C8 having cubic form (bond lengths, bond and torsion angles) using CCSD(T)/QZVP and DFT B3PW91/QZVP methods, has been carried out. NBO analysis data and HOMO/LUMO images for this compound are presented, too. Good agreement was found between the structural data obtained using the above two quantum-chemical methods and, also, with corresponding experimental data. Also, the standard thermodynamic parameters of formation of cubic C8 considered here, and namely standard enthalpy ΔfH0(298K), entropy Sf0(298K) and Gibbs’ energy ΔfG0(298K) of formation for this compound were calculated. By using this data, a theoretically possible variant of the synthesis of this compound by dehydrogenation of cubane C8H8 is considered, and the thermodynamic characteristics of each of the four stages of this process have been calculated. It is noted that each of the four stages of this process is characterized by a very high (about 500 kJ/mol) enthalpy of activation, as a result of that, for their realization within a sufficiently short time, the use of appropriate catalysts is necessary.

Copper macrocyclic complex with trans-di[benzo]-porphyrazine and two oxo ligands: DFT quantum-chemical design

2021 ◽  
pp. A-F
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Quantum Chemical ◽  
Structural Parameters ◽  
Dft Method ◽  
Nbo Analysis ◽  
Macrocyclic Complex ◽  
Chemical Calculation ◽  
Entropy Formula ◽  
Energy Formula ◽  
Thermodynamic Parameters Of Formation ◽  
Benzo Derivative

Based on the results of a quantum chemical calculation using the DFT method in the OPBE/TZVP and B3PW91/TZVP, the possibility of the existence of a copper heteroligand complex with trans-di[benzo]derivative of 3,7,11,15-tetraazaporphine (trans-di[benzo]porphyrazine) and two oxygen (O[Formula: see text] ions that is still unknown for this element was shown. In addition, the data on the structural parameters, the multiplicity of the ground state, NBO analysis and standard thermodynamic parameters of formation (standard enthalpy [Formula: see text], entropy [Formula: see text] and Gibbs’s energy [Formula: see text] for this complex are presented.

Spectral and bonding properties of bis(N,N-disubstituted-dithiocarbamato)iron(III)dihalide complexes studied by experimental and EHMO quantum-chemical methods

1985 ◽  
Vol 63 (11) ◽  
pp. 3249-3255 ◽  
Author(s):  
George A. Katsoulos ◽  
Constantinos A. Tsipis ◽  
Fotios D. Vakoulis
Keyword(s):  
Magnetic Susceptibility ◽  
Thermogravimetric Analysis ◽  
Quantum Chemical ◽  
Analysis Data ◽  
Spectroscopic Methods ◽  
Chemical Methods ◽  
Magnetic Systems ◽  
Quantum Chemical Methods ◽  
Bonding Properties ◽  
New Compounds

A new series of homobinuclear iron(III) halobisdithiocarbamate complexes antiferromagnetically coupled through a molecular halogen bridging unit has been synthesised and studied. The complexes have been characterized chemically and by spectroscopic methods and magnetic susceptibility measurements. The volatility characteristics and thermogravimetric analysis data for the new compounds are also studied. Finally, quantum-chemical calculations have been used to provide a qualitative guide to the possible pathways for the superexchange processes observed in these molecular magnetic systems, as well as to interpret their electronic spectra.

scholarly journals VIBRATION SPECTRUM AND MOLECULAR STRUCTURE OF 3-AMINOPHTHALIMIDE BY IR SPECTROSCOPY AND QUANTUM-CHEMICAL CALCULATION

2018 ◽  
Vol 59 (3) ◽  
pp. 35
Author(s):  
Denis S. Savelyev ◽  
Mikhail K. Islyaikin ◽  
Georgiy V. Girichev
Keyword(s):  
Molecular Structure ◽  
Ir Spectroscopy ◽  
Ir Spectra ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Vibration Spectrum ◽  
Low Frequency ◽  
Chemical Calculation ◽  
Chemical Methods ◽  
Quantum Chemical Methods

The IR spectra of solid 3-aminophthalimide (3-AF) were obtained and interpreted. Quantum-chemical calculations of vibration spectra were performed at different theory levels. Comparison of experimental and calculated IR spectra shows a variability of quantum chemical methods in predicting vibration spectrum in low-frequency field and fine features of geometric structure of the molecule of 3-AF.

Quantum chemical calculation of NIR spectra of practical materials

NIR news ◽  
2017 ◽  
Vol 28 (2) ◽  
pp. 13-20 ◽  
Author(s):  
Christian W Huck ◽  
Krzysztof B Beć ◽  
Justyna Grabska ◽  
Yukihiro Ozaki
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Nir Spectroscopy ◽  
Practical Significance ◽  
Chemical Calculation ◽  
Complex Molecules ◽  
Theoretical Approaches ◽  
Quantum Chemical Methods ◽  
Experimental Spectroscopy ◽  
Spectral Data Analysis

In the third issue of the series on modern quantum chemical methods in the support role of NIR spectroscopy we continue to introduce the researchers from the field of experimental spectroscopy to practical aspects and applications of modern anharmonic theoretical approaches. The first two issues focused on explaining the necessary theoretical and practical background, allowing readers to get more familiar with the topic. An overview of recent literature reports highlighted the advantages stemming from using quantum chemical calculation in the support role to NIR spectroscopy. These deliberations were based on several cases of small- to medium-sized molecules. This part overviews the topic of applications of quantum theoretical methods to complex molecules with practical significance, which typically prove to be challenging objects for theoretical studies. An exemplary application of presented methodology to the case of Rosmarini folium biological samples is also examined here. The rosemary specific active compound, rosmarinic acid, is a relatively complex polyphenol with growing phytopharmaceutical importance, and therefore provides an excellent object of applied studies. The possibilities of combining the information stemming from quantum chemical calculation with the methods of advanced spectral data analysis, which are commonly used in experimental NIR spectroscopy (chemometrics, two-dimensional (2D) correlation spectra) are also overviewed. Again, these deliberations are based directly on the most recent reports published in the field.

scholarly journals SYNTHESIS AND STRUCTURE OF NEW DERIVATIVES OF 10-R-4-METHYL-1,8-DINITRO-3-OXA-5,10-DIAZATRICYCLO[6.3.1.02.6]DODECA-2(6),4-DIENE

2019 ◽  
Vol 63 (1) ◽  
pp. 4-10
Author(s):  
Loik G. Mukhtorov ◽  
Yevgenia V. Ivanova ◽  
Igor' V. Blokhin ◽  
Yuri M. Atroshchenko ◽  
Ivan V. Fedyanin ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Quantum Chemical ◽  
Analysis Data ◽  
Point Of View ◽  
Rigid Base ◽  
Elemental Analysis Data ◽  
Chemical Calculation ◽  
Benzene Nucleus ◽  
Oxazole Ring ◽  
Derivatives Of

The spatial and electronic structure of 2-methyl-5,7-dinitrobenzo[d]oxazole, which is the substrate for the synthesis of hydride σ-adducts, was studied by the DFT/B3LYP/aug-cc-pVDZ method. Analysis of the charges on the atoms showed that the largest positive NBO charge is concentrated on the carbon atom C2 of the oxazole ring, while the carbon atoms C4 and C6 annelated benzene nucleus have the highest Mulliken charges both in the gas phase and in water. Thus, it has been established that a rigid base, a methoxide ion, is attached to the carbon atom C2, which is a hard reaction center, and a reaction with a soft base, a hydride ion, can also proceed through softer reaction centers — carbon atoms of the benzene ring C4 and C6. The bond lengths calculated by the quantum-chemical method are in good agreement with the experimental data obtained by X-ray diffraction, which confirms the correctness of the choice of the quantum-chemical calculation method. New derivatives of 3-azabicyclo [3.3.1]nonane have been synthesized by Mannich condensation of 2-methyl-5,7-dinitrobenzo[d]oxazole hydride σ-adduct with methylamine and β-aminopropanoic acid. This method is distinguished by relative simplicity, availability of reagents and allows under mild conditions to transfer from the aromatic system activated by nitro groups to 3-azabicyclo[3.3.1]nonane derivatives containing the nitro groups that are promising from the point of view of further functionalization. The structure of the compounds obtained was proved by IR, 1H-, 13C-, two-dimensional correlation NMR spectroscopy, as well as elemental analysis data. It was shown that the compounds obtained can serve as the basis for the creation of hybrid physiologically active compounds containing both a 3-azabicyclononane fragment and an oxazole cycle.

scholarly journals Quantum-Chemical Consideration of Al2M2 Tetranuclear Metal Clusters (M–3d-Element): Molecular/Electronic Structures and Thermodynamics

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6836
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Electronic Structures ◽  
Quantum Chemical ◽  
Metal Clusters ◽  
Molecular Structures ◽  
Chemical Calculation ◽  
Geometric Form ◽  
Structural Isomers ◽  
Torsion Angles ◽  
Homo And Lumo ◽  
The Given

Quantum-chemical calculation of most important parameters of molecular and electronic structures of tetra-nuclear (pd) metal clusters having Al2M2 composition, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn (bond lengths, bond and torsion angles), and HOMO and LUMO of these compounds by means of DFT OPBE/QZVP method, have been carried out. It has been found that, for each of these metal clusters, an existence of rather large amount of structural isomers different substantially in their total energy, occurs. It has been noticed that molecular structures of metal clusters of the given type differ significantly between them in terms of geometric parameters, as well as in geometric form, wherein the most stable modifications of metal clusters considered are similar between themselves in geometric form. In addition, the standard thermodynamic parameters of formation of metal clusters considered here, and namely standard enthalpy ΔfH0(298 K), entropy Sf0(298 K), and Gibbs’ energy ΔfG0(298 K) of formation for these metal clusters, were calculated.

Examination on Permittivity Estimation of Hydrocarbon-based Thermosetting Resin based on Quantum Chemical Calculation

2017 ◽  
Vol 137 (11) ◽  
pp. 626-631 ◽  
Author(s):  
Yuki Fuchi ◽  
Ryota Nakasako ◽  
Masahiro Kozako ◽  
Masayuki Hikita ◽  
Nobuhito Kamei
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Chemical Calculation ◽  
Thermosetting Resin

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Sign in / Sign up

Export Citation Format

Share Document