SOLID-STATE C-13 AND H-1-NMR STUDY OF ANOMALOUS ACID SALTS OF DIBASIC CARBOXYLIC-ACIDS

High-resolution solid-state C-13 and H-1 NMR techniques were used to study the structure of a number of anomalous acid salts of adipic, azelaic, dodecanedioic, maleic and fumaric acids. To assist in the understanding of these results, solid-state NMR data were also obtained for the corresponding acids and a number of their 'normal' salts. The resulting information provides insights into the solid structure of these complexes, including approximations of the length of the hydrogen bonds present in these systems. Strong evidence is given for the presence of a symmetrical hydrogen bond for tetramethylammonium didodecanedioate. Carbon-13 NMR measurements carried out over a range of temperatures have revealed differences in the behavior of several of these compounds which may provide clues regarding the nature of the hydrogen bond in these systems.