Temperature dependence of the ¹J(¹¹B¹⁹F) spin–spin coupling in BF₃ molecule

Abstract

The (1)J((11)B(19)F) spin-spin coupling of gaseous BF(3) was observed in (11)B NMR spectra as a function of density in a wide range of temperatures. Following the extrapolation of the measured values to the zero-density limit, the coupling constant free from intermolecular effects (1)J(0)((11)B(19)F) was obtained for each temperature. In contrast to previous investigations, the final results indicate a nonlinear dependence of (1)J(0)((11)B(19)F) on temperature. In the corresponding ab initio calculations of spin-spin coupling constants performed at the coupled cluster singles and doubles (CCSD) level to obtain a reliable result for this coupling constant we had to take into account large vibrational corrections.

Composition Determination of Low-Pressure Gas-Phase Mixtures by 1H NMR Spectroscopy

“…On the other hand, gas-phase samples are in direct contact with every part of the sample tube, which can lead to problems with sample storage and with temperature/density gradients. Due to the design of NMR sample thermostats, a gas-phase sample in a full-length (17 cm) NMR tube experiences a temperature/density gradient . Control experiments (described in the Supporting Information) showed that these gradients did not influence the mole fraction determination for the methane–propane samples.…”

“…This was necessary because good peak shapes are required for the integral-width and peak-overlap corrections that were done as part of the data analysis (see below). Of course, if desired, it is possible to use a deuterium-containing external reference that is contained in a sealed capillary or a coaxial tube. , The advantages of this approach include the ability to use automated shimming and frequency locking. The disadvantages include a reduction in the volume of gas-phase sample in the active region of the NMR tube and the need to do peak-overlap corrections for the reference peaks.…”

Analysis of the interactions in FCCF:(H2O) and FCCF:(H2O)2 complexes through the study of their indirect spin–spin coupling constants

“…Relativistic corrections [46] can safely be ignored for the molecules in this study but vibrational corrections [47,48] or bulk solvent effects [49,50] should in principle be considered. High-level calculations of vibrational corrections at the CCSD level of theory are still very rare [19,[51][52][53] due to their high cost compared to e.g. SOPPA [54][55][56] or DFT [57,58] calculations.…”

“…To our knowledge, vibrational corrections to couplings involving fluorine were so far studied only for very few and very small molecules, i.e. HF [57], HFH − [59], FCCF [19] and BF3 [51]. Additional bulk solvent effects could be studied either by a continuum model like PCM [49,60] or the QM/MM approach [50].…”

Nuclear Magnetic Resonance (NMR) Spectroscopy for the In Situ Measurement of Vapor–Liquid Equilibria

“…NMR spectroscopy is a well-established technique for the quantitative analysis of liquid-phase samples. − Although much less common, NMR spectroscopy has also been used for the quantitative analysis of vapor-phase samples, − and Suiter et al provide a thorough analysis of the uncertainty in vapor-phase compositions . NMR has been used to probe the composition of multiphasic liquid mixtures, although this type of work is uncommon and typically semiquantitative. − NMR spectroscopy has been suggested , as a method for VLE measurements.…”