2-Chloro-2,2-difluoracetamide (ClF2CC(O)NH2). Thermal Decomposition, Vapour Infrared, Mass Spectrometry, Low-temperature NMR, and Theoretical Studies. Solvent Effects on Conformational Preferences

2011 ◽  
Vol 64 (10) ◽  
pp. 1366 ◽  
Author(s):  
Ana G. Iriarte ◽  
Edgardo H. Cutin ◽  
Gustavo A. Argüello
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Vapour Phase ◽  
Basis Sets ◽  
Conformational Preferences ◽  
Ft Ir ◽  
Energy Surfaces

Gas-phase thermal decomposition of 2-chloro-2,2-difluoracetamide (CDFA) was studied at temperatures between 270 and 290°C. The rate constant for the decomposition follows the Arrhenius equation. Mass spectrometry was used to analyze the decomposition pattern of the title compound. The FT-IR spectrum of the vapour phase and the infrared spectra of CDFA in protic and aprotic solvents were recorded. Potential energy surfaces were studied by theoretical calculations performed at the density functional theory level (PBEPBE and B3LYP methods) using the 6-31G*, 6-31+G*, 6-311+G**, aug-cc-pVDZ, and aug-cc-pVTZ basis sets.

Theoretical Investigation of the Decarbonylation of Acetaldehyde by Ni+2 Using Density Functional Theory

2013 ◽  
Vol 446-447 ◽  
pp. 168-171
Author(s):  
Hong Fei Liu ◽  
Xin Min Min ◽  
Hai Xia Yang
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Transition Metal Ions ◽  
Basis Sets ◽  
Functional Theory ◽  
Representative System ◽  
Energy Surfaces ◽  
Ground Potential

The decarbonylation of acetaldehyde assisted by Ni+2, which was selected as a representative system of transition metal ions assisted decarbonylation of acetaldehyde, has been investigated using density functional theory (B3LYP) in conjunction with the 6-31+G** basis sets in C,H,O atoms and Lanl2dz basis sets in Ni atom The geometries and energies of the reactants, intermediates, products and transition states relevant to the reaction were located on the triplet ground potential energy surfaces of [Ni, O, C2,H4]+2. Our calculations indicate the decarbonylation of acetaldehyde takes place through four steps, that is, encounter complexation, CC activation, aldehyde H-shift and nonreactive dissociation, it is that CC activation by Ni+2that lead to the decarbonylation of acetaldehyde.

THEORETICAL STUDY OF GLYCINE CONFORMERS

2008 ◽  
Vol 07 (04) ◽  
pp. 889-909 ◽  
Author(s):  
HONG-WEI KE ◽  
LI RAO ◽  
XIN XU ◽  
YI-JING YAN
Keyword(s):  
Potential Energy Surfaces ◽  
Density Functional ◽  
Polarizable Continuum Model ◽  
Basis Sets ◽  
Dft Methods ◽  
Solvent Interactions ◽  
Solvation Effects ◽  
Moller Plesset ◽  
Energy Surfaces ◽  
Polarizable Continuum

Glycine conformers were investigated with three density functional theory (DFT) methods (B3LYP, PBE1PBE, X3LYP), and the second order Møller–Plesset perturbation theory (MP2) combined with basis sets of 6-31+G*, aug-cc-pVDZ, and aug-cc-pVTZ. Solvation effects were considered by using polarizable continuum model. Results from B3LYP and X3LYP were in generally good agreement with those of MP2, while PBE1PBE was shown to be inferior for the description of conformational potential energy surfaces. Conformers Ip, IIp, IIn, IIIp, IIIn, and IVn were all found to be low-lying states within 2.0 kcal/mol, with Ip being the global minimum in gas phase. Solvation effects can significantly change the nature of the conformational surfaces of glycine. A proper description of conformational equilibrium demands for a good treatment of both long-range and short-range solute–solvent interactions.

scholarly journals Experimental and DFT studies of Mtpnm

2014 ◽  
Vol 70 (a1) ◽  
pp. C1694-C1694
Author(s):  
Tufan Akbal ◽  
Erbil Agˇar ◽  
Sümeyye Gümüş ◽  
Ahmet Erdönmez
Keyword(s):  
Density Functional Theory ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Dipole Moments ◽  
Dft Studies ◽  
Acta Cryst ◽  
Functional Theory ◽  
Structure Density ◽  
Energy Surfaces

Experimental and DFT studies of (Z)-N-[3- Methoxy -5-(trifluormethyl) phenyl]-1-(5- nitrothiophene -2- yl)methanamine Tufan Akbala, , Erbil Agˇarb, Sümeyye Gümüşb and Ahmet Erdönmeza aDepartment of Physics, Ondokuz Mayıs University, Samsun, Turkey . b Department of Chemistry Ondokuz Mayıs University, Samsun, Turkey E-mail: [email protected] The title molecule, C13H12N2O3F3S, is nonplanar with an interplanar angle of 23.94(23)0 between the benzene and thiophene rings. In the crystal there exist only weak intermolecular C–H...O interactions and π...π interactions between the benzene rings and thiophene rings [centroid–centroid distance= 4.892(3) A0]. The length of the C9=N2 double bond is 1.2534 A0. This value agrees well with the analogous bond reported elsewhere. [1,2]. The theoretical calculations were performed with Gaussian03W software. In calculations, the stable structure geometries of the isolated molecules in the gas phase was investigated under the framework of Density Functional Theory (DFT). In order to find the stable molecular geometries, the global minimum scanning were performed on the potential energy surfaces and some properties of molecules such as charge densities, dipole moments and frontier orbitals (HOMO and LUMO) from B3LYP/6-31G(d) calculations. REFERENCES: [1] Akbal T., Agˇar E., Erdönmez A., 2012. Acta Cryst. E68, 2673. [2] Aygün M., Işık Ş., Öcal N., Nawaz T.M., Kaban Ş. & Büyükgüngör O., 1998. Acta Cryst. C54, 527-529. Keywords: tautomerism, crystal and molecular structure, density functional theory(DFT) studies

A Density Functional Theory Study of the Cu+ · O2 and Cu+ · N2 Adducts

2012 ◽  
Vol 67 (2) ◽  
pp. 118-126 ◽  
Author(s):  
Jamal N. Dawoud ◽  
Ismail I. Fasfous ◽  
Amin F. Majdalawieh
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Theoretical Data ◽  
Basis Sets ◽  
Dft Methods ◽  
Functional Theory ◽  
Linear Configuration ◽  
Energy Surfaces

The geometries and harmonic vibration frequencies of the Cu+ ·O2 and Cu+ ·N2 are determined by various density functional theory (DFT) methods employing different basis sets. The potential energy surfaces (PES) are examined. The Cu+ ·O2 adduct exhibits a bent structure with a binding energy of 12.4 kcal mol−1, whereas Cu+ ·N2 exhibits a linear configuration with a binding energy of 23.5 kcal mol−1. The binding energy values for the two adducts agree well with the available published experimental and theoretical data and hence are reliable.

THEORETICAL STUDY ON THE H2 ACTIVATION BY PtO+ AND ${\rm PtO}_{2}^{+}$ IN THE GAS PHASE

2010 ◽  
Vol 09 (06) ◽  
pp. 963-974 ◽  
Author(s):  
YONGCHUN TONG ◽  
QINGYUN WANG ◽  
DONGQING WU ◽  
YONGCHENG WANG
Keyword(s):  
Potential Energy ◽  
Gas Phase ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Reaction Pathway ◽  
Minimum Energy ◽  
Basis Sets ◽  
Avoided Crossing ◽  
Pass Through ◽  
Energy Surfaces

Gas-phase H2 activation by PtO+ and [Formula: see text] were studied at the density functional level of theory (DFT) using the relativistic effective core potential (RECP) of Stuttgart basis sets on platinum atom and UB3LYP/6-311+G(2d,2p) level on hydrogen and oxygen atoms. Two reaction profiles corresponding to the doublet and quartet multiplicities were investigated in order to ascertain the presence of some spin inversion during the H2 reduction. The electron-transfer reactivity of the reactions were analyzed using the two-state model, and the strongly crossing behavior on the transition state (TS) area were shown. Finally, the actions of frontier molecular orbitals in minimum-energy crossing point (MECP) have been illuminated briefly. These theoretical results can act as a guide to further theoretical and experimental research. H2 activation mediated by metal oxide cations were found to be an exothermic spin-forbidden process resulting from a crossing between quartet and doublet profiles. To evaluate the spin-forbidden process in the reaction pathway, the spin-obit coupling (SOC) matrix elements are calculated at the MECP with the different potential energy surfaces (PESs) and the probability of crossing between the adiabatic potential-energy surfaces during a single pass through the avoided crossing region was described. Therefore, the intersystem crossing (ISC) at crossing points (CP) occur efficiently because of the large SOC (ca. 85.58 cm-1) involved.

Theoretical study on the formation of carbon disulfide and ammonia from thermal decomposition products of thiourea

2014 ◽  
Vol 13 (04) ◽  
pp. 1450022 ◽  
Author(s):  
Zerong Daniel Wang ◽  
Meagan Hysmith ◽  
Perla Cristina Quintana
Keyword(s):  
Thermal Decomposition ◽  
Carbon Disulfide ◽  
Density Functional ◽  
Basis Sets ◽  
Structural Isomer ◽  
Consecutive Reaction ◽  
Functional Theory ◽  
Decomposition Products ◽  
Thermal Decomposition Products ◽  
Hybrid Module

The formation of carbon disulfide ( CS 2) and ammonia ( NH 3) from the thermal decomposition products of thiourea has been studied with MP2, and hybrid module-based density functional theory methods (B3LYP, MPW1PW91 and PBE1PBE), each in conjunction with five different basis sets (6-31+G(2d,2p), 6-311++G(2d,2p), DGDZVP, DGDZVP2 and DGTZVP). The free energy changes and activation energies for all the five primitive reactions involved in the formation of CS 2 and NH 3 have been compared and discussed. The results indicate that CS 2 is most likely formed in a consecutive reaction path that consists of the addition of hydrogen sulfide ( H 2 S ) to isothiocyanic acid (HNCS) to generate carbamodithioic acid and subsequent decomposition of carbamodithioic acid. By contrast, thiocyanic acid (HSCN) as the structural isomer of isothiocyanic acid is not likely the source of CS 2.

scholarly journals Quantum Chemical Calculations on CHOP Derivatives—Spanning the Chemical Space of Phosphinidenes, Phosphaketenes, Oxaphosphirenes, and COP− Isomers

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3341 ◽  
Author(s):  
Alicia Rey ◽  
Arturo Espinosa Ferao ◽  
Rainer Streubel
Keyword(s):  
Potential Energy Surfaces ◽  
Chemical Space ◽  
Theoretical Calculations ◽  
Kinetic Energy Density ◽  
Ring Strain ◽  
Starting Point ◽  
Time Calculation ◽  
Bonding Properties ◽  
Anionic Ring ◽  
Energy Surfaces

After many decades of intense research in low-coordinate phosphorus chemistry, the advent of Na[OCP] brought new stimuli to the field of CHOP isomers and derivatives thereof. The present theoretical study at the CCSD(T)/def2-TZVPP level describes the chemical space of CHOP isomers in terms of structures and potential energy surfaces, using oxaphosphirene as the starting point, but also covering substituted derivatives and COP− isomers. Bonding properties of the P–C, P–O, and C–O bonds in all neutral and anionic isomeric species are discussed on the basis of theoretical calculations using various bond strengths descriptors such as WBI and MBO, but also the Lagrangian kinetic energy density per electron as well as relaxed force constants. Ring strain energies of the superstrained 1H-oxaphosphirene and its barely strained oxaphosphirane-3-ylidene isomer were comparatively evaluated with homodesmotic and hyperhomodesmotic reactions. Furthermore, first time calculation of the ring strain energy of an anionic ring is described for the case of oxaphosphirenide.

scholarly journals The ANI-1ccx and ANI-1x Data Sets, Coupled-Cluster and Density Functional Theory Properties for Molecules

2020 ◽  
Author(s):  
Justin S. Smith ◽  
Roman Zubatyuk ◽  
Benjamin T. Nebgen ◽  
Nicholas Lubbers ◽  
Kipton Barros ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Atomic Charge ◽  
Density Functional Theory Calculations ◽  
Coupled Cluster ◽  
Data Sets ◽  
Data Set ◽  
Functional Theory ◽  
Energy Surfaces

<p>Maximum diversification of data is a central theme in building generalized and accurate machine learning (ML) models. In chemistry, ML has been used to develop models for predicting molecular properties, for example quantum mechanics (QM) calculated potential energy surfaces and atomic charge models. The ANI-1x and ANI-1ccx ML-based eneral-purpose potentials for organic molecules were developed through active learning; an automated data diversification process. Here, we describe the ANI-1x and ANI-1ccx data sets. To demonstrate data set diversity, we visualize them with a dimensionality reduction scheme, and contrast against existing data sets. The ANI-1x data set contains multiple QM properties from 5M density functional theory calculations, while the ANI-1ccx data set contains 500k data points obtained with an accurate CCSD(T)/CBS extrapolation. Approximately 14 million CPU core-hours were expended to generate this data. Multiple QM properties from density functional theory and coupled cluster are provided: energies, atomic forces, multipole moments, atomic charges, and more. We provide this data to the community to aid research and development of ML models for chemistry.</p>

scholarly journals Migration of Zeolite-Encapsulated Pt and Au Under Reducing Atmospheres

2021 ◽  
Author(s):  
Dianwei Hou ◽  
Christopher Heard
Keyword(s):  
Monte Carlo ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Noble Metals ◽  
Kinetic Monte Carlo ◽  
Pore System ◽  
Kinetic Monte Carlo Simulations ◽  
Zeolite Lta ◽  
Metal Migration ◽  
Energy Surfaces

Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ significantly in the strength and type of interaction with the framework, with strong, framework breaking interactions between Pt and and the zeolite, but only weak dispersive interactions between Au and the zeolite. Adsorbates are found to dramatically interfere with Pt-framework binding, leading to poorer atom-trapping, enhanced metal migration and faster equilibration.

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