نتایج جستجو برای: bond stretching
تعداد نتایج: 85676 فیلتر نتایج به سال:
In this article, the optimized geometry, IR and UV spectra, frontier orbital analysis, natural bond orbital (NBO) analyses, and thermodynamic parameters of pomalidomide were investigated. The calculated structural parameters and stretching frequencies values are compared with experimentalvalues of the investigated compound. Also, the relations of the thermodynamic functions vs.temperatures were...
The nitridorhenium(V) complexes ReNCl(2)(PCy3)(2) (1), ReNBr(2)(PCy3)(2) (2), ReNCl(2)(PPh3)(2) (3), and ReNBr(2)(PPh3)(2) (4) produce structured emission spectra upon excitation at low temperature. The origin, E(00), occurs at 15 775, 16 375, 15 875, and 16 300 cm(-1), respectively. The vibronic peaks are regularly spaced with an average energy separation corresponding to the Re triple bond N ...
A semiflexible harmonic chain model with extensible bonds is introduced and applied to the stretching of semiflexible polymers or filaments. The semiflexible harmonic chain model allows to study effects from bending rigidity, bond extension, discrete chain structure, and finite length of a semiflexible polymer in a unified manner. The interplay between bond extension and external force can be d...
Isoelectronic C=F(+) and C=O bonds contained in fluoro-substituted carbenium ions, aldehydes, and ketones are investigated with regard to their bond properties by utilizing the vibrational spectra of these molecules. It is demonstrated that bond dissociation energies (BDEs), bond lengths, vibrational stretching frequencies, and bond densities are not reliable descriptors of the bond strength. T...
The effect of fluorine substitution on the hydrogen bond strength in alcohol-amine molecular complexes was investigated, with a combination of vapour phase infrared spectroscopy and theoretical calculations. The complexes were combined from methanol (MeOH), ethanol (EtOH) and trifluoroethanol (TFE) as the hydrogen bond donor, and either dimethylamine (DMA) or trimethylamine (TMA) as the accepto...
We have performed first-principles calculations to investigate the behavior of the hydrogen bond in δ-AlOOH under pressure. The highest OH-stretching A1 and B2 mode frequencies decrease under pressure leading to hydrogen bond symmetrization. After hydrogen bond symmetrization, the corresponding frequencies gradually increase. This softening and subsequent hardening of the OH bonds is a good spe...
A set of 42 molecules with N-F, O-F, N-Cl, P-F, and As-F bonds has been investigated in the search for potential bond anomalies, which lead to reverse bond length-bond strength (BLBS) relationships. The intrinsic strength of each bond investigated has been determined by the local stretching force constant obtained at the CCSD(T)/aug-cc-pVTZ level of theory. N-F or O-F bond anomalies were found ...
The dynamics of vibrational energy relaxation (VER) of the OH-stretching vibration of HOD in liquid-to-supercritical heavy water is studied as a function of temperature and solvent density by femtosecond mid-infrared spectroscopy. Using the dielectric constant of the fluid both, the OH-stretching absorption frequency and the VER rate, can be correlated phenomenologically with the average hydrog...
The OH bond of methanol, ethanol and t-butyl alcohol becomes more anharmonic upon hydrogen bonding and the infrared intensity ratio between the overtone and the fundamental transition of the bridging OH stretching mode decreases drastically. FTIR spectroscopy of supersonic slit jet expansions allows to quantify these effects for isolated alcohol dimers, enabling a direct comparison to anharmoni...
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