[NMR paper] Insight into Magnesium Coordination Environments in Benzoate and Salicylate Complexes through (25)Mg Solid-State NMR Spectroscopy.

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Insight into Magnesium Coordination Environments in Benzoate and Salicylate Complexes through (25)Mg Solid-State NMR Spectroscopy.

Insight into Magnesium Coordination Environments in Benzoate and Salicylate Complexes through (25)Mg Solid-State NMR Spectroscopy.

J Phys Chem A. 2013 Jul 8;

Authors: Burgess KM, Xu Y, Leclerc MC, Bryce DL

Abstract
We report on the 25Mg solid-state nuclear magnetic resonance (NMR) characterization of a series of magnesium complexes featuring Mg2+ ions in organic coordination environments. Six compounds have been synthesized with benzoate and salicylate ligands, which are typically used as linkers in metal organic frameworks (MOFs). The use of ultrahigh-field solid-state NMR has revealed a relatively large range of values for the 25Mg quadrupolar coupling constant, CQ(25Mg), in these compounds. In contrast to some previously studied inorganic Mg2+ complexes, the values of CQ(25Mg) in organic Mg2+ complexes are well rationalized by the degree of octahedral strain of the 'MgO6' coordination polyhedra. 13C and 25Mg isotropic chemical shifts were also found to be sensitive to the binding mode of the carboxylate ligands. The experimental findings are corroborated by gauge-including projector-augmented-wave (GIPAW) density functional theory (DFT) computations and these have allowed for an interpretation of the experimentally observed trend in the CQ(25Mg) values and for the visualization of the EFG tensor principal components with respect to the molecular structure. These new insights may prove to be valuable for the understanding and interpretation of 25Mg NMR data for Mg2+ ions in organic binding environments such as those found in MOFs and protein-divalent metal binding sites.


PMID: 23834478 [PubMed - as supplied by publisher]



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