Volumssuszeptibilit�tsmessungen mit kernmagnetischer Resonanzspektroskopie

Intrinsic Barriers for Electron and Hydrogen Atom Transfer Reactions of Biomimetic Iron Complexes

“…Eyring analysis (284-333 K) gives ∆H q ) 4.4 ( 0.7 kcal mol -1 and ∆S q ) -26 ( 2 cal K -1 mol -1 . The same rate constants are obtained using Fe II (H 2 bim)-d 24 and Fe III -(Hbim)-d 24 and measuring the change in CD line widths. In DMSO-d 6 , k H • ) (1.9 ( 0.2) × 10 4 M -1 s -1 at 298 K, three times faster than the rate in MeCN-d 3 , and approximately four times slower than k e -in the same solvent.…”

“…The inverse relation between temperature and shift is characteristic of Curie paramagnets, whereas the increase in line width with temperature, although not unusual, has a more complex nature. 31 The 2 H NMR spectra of Fe II (H 2 bim)-d 24 and Fe II (D 2 bim)-d 30 are significantly sharper than the proton spectrum, with Lorenzian signals at δ 10.5 (14 Hz), δ 24.7 (13 Hz), and δ 45.8 (62 Hz). Deuterium spectra of paramagnets can be as much as 42 times sharper than analogous proton spectra (the square of the ratio of nuclear gyromagnetic constants of H and D), but the full effect is rarely observed and the spectral resolution is partially balanced by the 6.5-fold decrease in chemical shift dispersion in the 2 H spectrum.…”

“…In none of the experiments did the signal due to the internal standard broaden. The reported moments are corrected for the diamagnetic susceptibilities of the solvent, ligands (104 × 10 -6 cgs), ClO 4 - (34 × 10 -6 cgs), and Fe 2+ (13 × 10 -6 cgs) or Fe 3+ (10 × 10 -6 cgs) ions. 15b, …”

Ambient temperature 1H/13C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D2O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples

“…In general, this way of finding the δ χ term is not accurate, due to the large differences in χ v data available in the literature. Great discrepancies between the classically calculated and NMR‐measured χ v values have been repeatedly reported 22,45–47 . Particularly, large discrepancies are found in the results of determining the temperature dependence of the mass χ m or the molar magnetic susceptibility χ M for H 2 O, and especially D 2 O, relevant to the present study 48–51 .…”

“…Great discrepancies between the classically calculated and NMR-measured χ v values have been repeatedly reported. 22,[45][46][47] Particularly, large discrepancies are found in the results of determining the temperature dependence of the mass χ m or the molar magnetic susceptibility χ M for H 2 O, and especially D 2 O, relevant to the present study. [48][49][50][51] This issue is critically reviewed and discussed in the Supporting Information part.…”