ABSTRACT:The data acquisition and processing of the wide-line chemical-shift NMR spectra of solids present unique challenges. Developing procedures to minimize and address inherent distortions is critical for the proper determination of NMR chemical-shift parameters from these wide-line spectra. The analysis of such data provides an understanding of many assumptions that are made about solids and liquids in spectroscopy. We discuss techniques for the analysis of spin-echo spectra broadened by chemical-shift dispersion.

Polymorphism, the presence of structurally distinct solid phases of the same chemical species, affords a unique opportunity to evaluate the structural consequences of intermolecular forces. The study of two polymorphs of 2,6-di-tert-butylnaphthalene by single-crystal x-ray diffraction, differential scanning calorimetry ͑DSC͒, 13 C magic-angle-spinning ͑MAS͒ nuclear magnetic resonance ͑NMR͒ spectroscopy, and 1 H NMR spin-lattice relaxation provides a picture of the differences in structure and dynamics in these materials. The subtle differences in structure, observed with x-ray diffraction and chemical shifts, strikingly affect the dynamics, as reflected in the relaxation measurements. We analyze the dynamics in terms of both discrete sums and continuous distributions of Poisson processes.

(207)Pb solid-state NMR studies have been conducted on binary lead-group 16 and mixed transition-metal/lead group 16 materials, correlating the NMR chemical shifts of the materials with their structures. The experimental results show that the (207)Pb chemical shifts are strongly influenced by the local electronic structure. Data are reported for lead selenide, lead selenate, calcium plumbate, strontium plumbite, barium plumbite, lead borate, lead zirconate, lead tungstate, lead meta-tantalate, lead niobate, lead molybdate, lead meta-vanadate, lead sulfite, and lead sulfate.

The temperature and concentration variations in 207Pb NMR shifts of Pb(NO3)2 in aqueous solutions are analyzed in terms of exchange between aquated lead ion and the Pb(NO3)+ ion complex according to the reaction PbNO3 +(aq) = Pb2+(aq) + NO3 -(aq). The analysis gives an enthalpy of dissociation of −3.0 ± 0.2 kcal mol-1 and an entropy of dissociation of −11.9 ± 0.4 cal K-1 mol-1.

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