نتایج جستجو برای: nbo analyses
تعداد نتایج: 386170 فیلتر نتایج به سال:
In this work we was study correlation between electronic structure of (R)-4-menthen-3-one and restricted transitions its conformers. By NBO analysis, carried out in ab inition methods, found special orbital interactions sterical effects conformers (R)-4-menthen-3-one, which explained difficults inversion rotation.
Phenylgermaniumpyridine-2-olate PhGe(pyO)3 (compound 1Ge) and CuCl react with the formation of heteronuclear complex Ph(pyO)Ge(μ2-pyO)2CuCl (2Ge’) rather than forming expected compound PhGe(μ2-pyO)3CuCl (2Ge). Single-point calculations (at B2T-PLYP level) optimized molecular structures confirmed relative stability isomer 2Ge’ over 2Ge and, for related silicon congeners, 2Si 2Si’. Decomposition ...
The conformational and structural properties of the inhalational anesthetic isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether) have been probed in a supersonic jet expansion using Fourier-transform microwave (FT-MW) spectroscopy. Two conformers of the isolated molecule were identified from the rotational spectrum of the parent and several (37)Cl and (13)C isotopologues detected in ...
In this study, nuclear magnetic resonance spectroscopy and nuclear quadrupole resonance spectroscopy parameters of N (Nitrogen in imidazole ring) in N–H...O hydrogen bonding for Histidine hydrochloride monohydrate were calculated via density functional theory. We considered a five-molecule model system of Histidine hydrochloride monohydrate. Also we examined the trends of environmental effect o...
The present study aims at a fundamental understanding of bonding characteristics of the C-Br and O-Br bonds. The target molecular systems are the isomeric CH3OBr/BrCH2OH system and their decomposition products. Calculations of geometries and frequencies at different density functional theory (DFT) and Hartree-Fock/Møller-Plesset (HF/MP2) levels have been performed. Results have been assessed an...
The structure of diglycolic anhydride (1,4-dioxane-2,6-dione; DGAn) isolated in a low-temperature argon matrix at 10 K was studied by means of FTIR spectroscopy. Interpretation of the experimental vibrational spectrum was assisted by theoretical calculations at the DFT(B3LYP)/aug-cc-pVTZ level. The optimized structure of the isolated DGAn molecule adopts an envelope conformation, which was foun...
Substances known as nitrogen mustards turn into aziridinium ion through the intramolecular cyclization SN1. This ion reacts with the DNA preferably at the N7 position of the guanine, and because of this, it is an important antineoplastic agent. Based on this, the objective of this study is to quantify the interaction between the nitrogen mustard mechlorethamine and the guanine, using the NBO an...
Mixed dimers, trimers and tetramers composed of SO2 and CO2 molecules are examined by ab initio calculations to identify all minimum energy structures. While AIM formalism leads to the idea of a pair of C···O bonds in the most stable heterodimer, bound by some 2 kcal mol(-1), NBO analysis describes the bonding in terms of charge transfer from O lone pairs of SO2 to the CO π* antibonding orbital...
Previously, we reported a reliable DU8 method for natural bond orbital (NBO)-aided parametric scaling of Fermi contacts to achieve fast and accurate prediction of proton-proton spin-spin coupling constants (SSCC) in (1)H NMR. As sophisticated NMR experiments for precise measurements of carbon-proton SSCCs are becoming more user-friendly and broadly utilized by the organic chemistry community to...
We study the kilohertz quasi-periodic oscillations (kHz QPOs) and the bandlimited noise (BLN) in the 0.5–16 Hz range observed simultaneously on the horizontal branch (HB) and on the upper normal branch (NB) of the brightest neutron star Low-mass X-ray Binary (LMXB) Scorpius X–1 with the observations performed with the Rossi X-Ray Timing Explorer (RXTE). We find that the twin kHz QPO frequencies...
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