Solid-State²⁵Mg NMR Study of Inner-Sphere Mg²⁺Binding Complexes

Recent Advances in Solid-State 25Mg NMR Spectroscopy

“…Besides the use of large volume samples, there are also other ''brute force'' approaches frequently used since the earlier reports of solid-state 25 Mg NMR, including isotopic enrichment and the use of magnetic fields as strong as possible. 6,37,39,42,43,[45][46][47][48][49][50][51][52] There is no doubt that the increase in the number of reports involving solid-state 25 Mg NMR has been driven by the wider availability of high-field magnets (e.g. !14.1T).…”

“…This is the case of MgSO 4Á 6H 2 O, for which the calculated d iso values of 7 and 4ppm allowed (together with the C q values mentioned above) the assignment of sites 1 and 2, with experimental d iso values of 6 and 5ppm, respectively. 40 Mg formate dihydrate is another example of this: the existence of two crystallographically distinct sites (but with close values of MgÀ ÀO bond lengths and OÀ ÀMgÀ ÀO bond angles) in 25 Mg NMR spectra was demonstrated using MQMAS by Sham and Wu,49 but no assignment of the NMR parameters to each site was possible. Cahill et al 40 studied this compound again, recording spectra at multiple magnetic field strengths and obtaining quadrupolar and shielding parameters different from those of Sham and Wu.…”

“…In one of the pioneering studies of Mg-containing organic compounds, Sham and Wu used 25 Mg-enriched samples (synthesised from MgO containing 99.1at.% 25 Mg) and determined the quadrupole parameters of a set of Mg 2þ -binding complexes taken as models for inner-sphere Mg 2þ coordination. 49 A number of other reports dealing with solid-state 25 Mg NMR studies in related Mg-containing organic compounds appeared thereafter, including acetate, chlorophyll, EDTA complex, ATP, proteins and hydroxyapatite. 41,48,[50][51][52]54,57,107,165 As mentioned before, two comprehensive and independent accounts were published recently, containing a large number of 25 Mg NMR experimental results in organic compounds (among others) and with detailed comparisons to DFT calculations.…”

Local Structure of Nanoscopic Magnesium Hydroxide ­Fluorides Studied by Natural Abundance 25Mg Solid State NMR Spectroscopy

“…Usually, most of the authors studied well crystalline inorganic magnesium compounds and magnesium containing minerals [1,6,7] but also samples of magnesium oxoanion compounds [8] or samples of biological importance were taken into account. [9] A recent and comprehensive survey was given by Pallister et al [5] The ultra-high field of 21.1 T used in that paper [5] made the evaluation of chemical shift and quadrupolar parameters of a broad range of crystalline magnesium-containing materials possible. These parameters are now a valuable tool for the study of chemically similar but disordered samples.…”

Solid‐state natural abundance 25Mg NMR studies of Na2MgEDTA·4H2O—a possible new reference compound for 25Mg NMR spectroscopy

“…With this approach, Sham and Wu determined the quadrupolar parameters of a set of Mg 2+ binding complexes taken as models for inner-sphere Mg 2+ coordination. [20] More recently, Wong et al reported an NMR study of two Mg organometallics with a square-pyramidal coordination type, one of these at natural abundance. [18] A limited number of other works have also dealt with solid-state 25 Mg NMR studies in related compounds.…”