³⁵Cl AND ³⁷Cl MAGNETIC RESONANCE OF SIMPLE CHLORINE COMPOUNDS

Abstract

The nuclear magnetic resonances of 35CI and 37C1 in a number of simple chlorine compounds were measured. Since both the paramagnetic contribution for chemical shift and the quadrupole coupling constant of the atom are determined by the same radial distribution of the electron, a linear relationship between the chemical shifts and the quadrupole coupling constants may be expected for compounds for which the electronic excitation energies are comparable. This was demonstrated for the series of chloro-substituted methanes. By graphical extrapolation the absolute chemical shift of the reference compound, NaCl aqueous solution, was obtained. The chemical shift of CI-aq. ion can be interpreted as the sum of the diamagnetic shift of C1-spherical ion and a paramagnetic shift resulting from its hydration. The experimental and theoretical values of the paramagnetic chemical shift of the Clr molecule were -2.06 X and -2.17 X respectively. Paramagnetic chemical shifts and line widths of resonance spectraof simple chlorine compoundsare discussed, as well as the feasibility of high-resolution chlorine resonances for structural applications.

33S NMR Spectroscopy. 2. Substituent Effects on33S Chemical Shifts and Nuclear Quadrupole Coupling Constants in 3- and 4-Substituted Benzenesulfonates. Correlation between Chemical Shifts and Nuclear Quadrupole Coupling Constants

“…It is well-known that Saika and Slichter 8 have approximated Ramsey's equation 9 as where σ d and σ p are, respectively, the diamagnetic and paramagnetic contributions to the screening constant for the observed atom. According to Jameson and Gutowsky, 10 the paramagnetic term for 33 S is χ values are also dependent on 〈r -3 〉 and on electron distribution around the nucleus: 11 In these equations m and e denote the electron mass and charge, respectively, ∆E is an average electronic excitation energy, 〈r -3 〉 is the expected value of the inverse cube of the mean radius of 3p and 3d orbitals, P u , P′ u , and D u , D′ u are functions of p and d orbitals populations, respectively, but have different expressions for δ and χ, and γ ∞ is the Sternheimer antishielding factor.…”

A tellurium-125 and tin-119 Mössbauer and nuclear magnetic resonance study of the group IV organotellurides

“…Thus there appears to be a rough correlation between these two parameters for tellurium-125. The existence of such a correlation between nmr chemical shifts and nuclear quadrupole coupling constants has been commented on pre-viously for terminal halogen ligands (17)(18)(19)(20)(21)(22). The origin of this correlation in l Z 5~e organotellurides in particular will be discussed elsewhere.…”

Structure-activity study of thiazides by magnetic resonance methods (NQR, NMR, EPR) and DFT calculations

“…3), and, as follows from the UV spectra [39,40], the mean excitation energies are close (differences do not exceed 0.5 eV). Hitherto, a linear relationship between the chemical shift and QQC has been observed only for very small molecules of chloromethanes [41].…”