Search results for " molecule"
showing 10 items of 1523 documents
Basis Set Convergence of Indirect Spin-Spin Coupling Constants in the Kohn-Sham Limit for Several Small Molecules
2012
The performance of more than 40 density functionals in predicting indirect spin-spin coupling constants (SSCCs) in the Kohn-Sham basis set limit was tested. For comparison, similar calculations were performed using the RHF, SOPPA, SOPPA(CC2), and SOPPA(CCSD) methods, and the results were estimated toward the complete basis set (CBS) limit. The SSCCs of nine small molecules (N(2), CO, CO(2), NH(3), CH(4), C(2)H(2), C(2)H(4), C(2)H(6), and C(6)H(6)) were calculated using the dedicated Jensen pcJ-n polarization-consistent basis sets and used for the CBS limit estimations within the Kohn-Sham limit. These CBS results were compared with calculations using the aug-cc-pVTZ-J basis set. Among the 4…
Theoretical nuclear spin-spin coupling constants using atom-atom polarizabilities.13CH and HH′ coupling constants of some [2.2.1] bicyclic compound…
1977
Full configuration-interaction and coupled-cluster calculations of the indirect spin–spin coupling constant of BH
2003
Abstract Full configuration-interaction calculations of the indirect spin–spin coupling constant of the BH molecule have been carried out in order to investigate the performance of various coupled-cluster (CC) methods in the treatment of electron-correlation effects, while the corresponding basis set convergence is analyzed in CC singles and doubles calculations. Assuming additivity of correlation and basis set effects, a theoretical estimate of 50.67 Hz is obtained for the 11 B 1 H spin–spin coupling constant.
New constraints on axion-mediated P , T -violating interaction from electric dipole moments of diamagnetic atoms
2018
The exchange of an axionlike particle between atomic electrons and the nucleus may induce electric dipole moments (EDMs) of atoms and molecules. This interaction is described by a parity- and time-reversal-invariance-violating potential which depends on the product of a scalar ${g}^{s}$ and a pseudoscalar ${g}^{p}$ coupling constant. We consider the interaction with the specific combination of these constants, ${g}_{e}^{s}{g}_{N}^{p}$, which gives significant contributions to the EDMs of diamagnetic atoms. In this paper, we calculate these contributions to the EDMs of $^{199}\mathrm{Hg}$, $^{129}\mathrm{Xe}$, $^{211}\mathrm{Rn}$, and $^{225}\mathrm{Ra}$ for a wide range of axion masses. Com…
Cover Feature: Electrochemical Installation of CFH 2 −, CF 2 H−, CF 3 −, and Perfluoroalkyl Groups into Small Organic Molecules (Chem. Rec. 9/2021)
2021
Reversible Dimerization of Tetraureas Derived from Calix[4]Arenes
1999
Calix[4]arene derivatives, substituted at the wider rim by four urea functions are easily available in great variety. In apolar solvents like benzene or chloroform they dimerize via NH…O=C hydrogen bonds encapsulating a single solvent molecule as guest. The exclusive formation of dimers has been proved in solution by NMR, while their shape has been characterized by single crystal X-ray analysis. The kinetic stability and the rate of the guest exchange have been studied by NOESY experiments using a derivative with lower symmetry.
Small Organic Molecules and Higher Homologs
2012
4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman
2000
The title compound, C23H28O2, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.
Electron Crystallography on Polymorphs
2006
Structure analysis via electron diffraction in combination with x-ray powder diffraction and simulation methods has been performed on single crystals of small organic molecules which form polymorphs. For two different examples of pigments and non-linear optical active material data collection, cell parameter and space group determination, structure analysis and refinement are discussed.