Notizen: ⁶⁷Zn NMR Anomalous Solvent Isotope Effect in Aqueous Solutions

Abstract

For 67Zn NMR lines of solutions of ZnCl2, ZnBr2, and Znl2 in H20 and D20 an anomalous solvent isotope effect is reported. In D20 solutions the lines are shifted to higher frequencies. The difference between the shieldings in H20 and D20 is e.g. o (H 20) -o(D20) = (13.1 ±0.7) ppm for a concentration of 0 .0 2 moles zinc bromide per mole solvent.The frequency of the NMR signal (Larmor fre quency) of a nucleus in an ion in aqueous solution can depend on the isotopic composition of the sol vent. Such a behaviour has been found for alkali 1-4, halide 115,6 and several other nuclei7-11 in aqueous salt solutions. The largest effect was observed for 20"Pb in aqueous lead salt solutions". The differ ence between the shieldings in H20 and D20 is ö (H20) -o (D20) = -(31 + 3) ppm for a concen tration of 0.004 moles lead nitrate per mole solvent. These shielding differences are presumably due to the different vibronic states of the H20 and D20 molecules surrounding the ions 5.For i n Cd an indication for a shift to higher frequency was found in a cadmium chloride solu tion n , whereas in perchlorate and nitrate solutions the usual solvent isotope effect was observed.During a NMR investigation of II b elements, 6'Zn NMR signals were observed in aqueous solu tions for a determination of the shielding constant12. The 6'Zn studies were done at 4.841 MHz in a field of 1.807 Tesla with a Fourier Transform Spectro meter basing on a Bruker pulse spectrometer KR 322 s. For experimental details see for example2.The dependence of the Larmor frequency of 67Zn on the concentration of aqueous zinc chloride, bro mide, and iodide solutions was measured. The ob served linewidths are in the range between 20 Hz for low and 170 Hz for high concentrations. For all these salts an anomalous shift to higher frequencies

Spies Within Metal-Organic Frameworks: Investigating Metal Centers Using Solid-State NMR

“…MAS experiments were performed using a Bruker 7 mm HX MAS probe at a spinning speed of 5 kHz. Chemical shifts were referenced to a 1.0 M solution of Zn(NO 3 ) 2 (aq) (δ iso = 0.0 ppm) . Specific parameters and conditions for the static echo, static WURST-CPMG, and MAS one-pulse experiments are listed in Table S1 in the Supporting Information.…”

“…Chemical shifts were referenced to a 1.0 M solution of Zn(NO 3 ) 2 (aq) (δ iso = 0.0 ppm). 72 Specific parameters and conditions for the static echo, static WURST-CPMG, and MAS one-pulse experiments are listed in Table S1 in the Supporting Information. A spikelet spacing of 5 kHz was used for WURST-CPMG spectra.…”

Nuclear magnetic resonance spectroscopy

“…High resolution PMR and 19F NMR spectra of HF in aprotic solvents (894), NMR studies of tetrameric methyllithium (895), lithium Group III and IV metallates (896), 7Li NMR of lithium cryptates (897), potassium isotope NMR studies of several systems (898), 23Na NMR of sodium cryptates (899), relaxation of alkali metal ions in aqueous solutions (900), 23Na NMR of sodium complexes (901), 43Ca NMR of solutions of various salts (902), 27Al NMR of aluminum chelates with hydroxycarboxylic acids (903), mixed ligand complexes (904), octahedral and tetrahedral solvates (905), bromotris(tetrahydroborato)aluminumate anion in tetrahydrofuran (906) and alumínate solutions (907), 29Si NMR of silicon-nitrogen compounds (908), methyl-and methylphenylsiloxanes (909), mixed methylhalide silanes (910), silicate solutions (911,914,916), silicon hydrides (912, 913, 915), 170 NMR of oxygen-nitrogen compounds (917), 19F (918) and 129Xe NMR of xenon compounds (919), 67Zn NMR of aqueous solutions (920,921), 4l3Cd NMR of cadmium solutions and complexes (922)(923)(924)(925)(926), NMR studies of mercury complexes (927, 928) and mercurinium ions (929), 207Pb NMR studies of solutions (930, 931, 933) and organometallic compounds (932,934), 72Ce, 47Ti, and 49Ti, 93Nb and 121Sb NMR studies (935), 71Ga NMR of aqueous gallium citrate (936), 119Sn NMR studies of organotin derivatives (937-941, 943-945) and 13C NMR of organotin compounds (942), 20°T1 NMR of aqueous solutions (946), 45Sc NMR of aqueous solutions (947,948), NMR studies of primary isotope effect on boron nuclear shielding (949), boron trihalide adducts (950), electronic effects in borazines (951), Jbh and Jbc in organoboron compounds (952), Jen in various boranes (953), interaction of borate with diols (954), nonaborane (13) carbonyl (955), borane adducts of trimethylamine (956), tetraalkylammonium tetraalkylborides (957), 79Br NMR of aqueous solutions of KBr containing various mercury compounds (958), 13C NMR of silver olefi...…”