A new polymorph of ammonium succinate - serendipity in action.

Succinic acid has been known since 1546 and was first chemically identified in the mid-19th century. In an attempt to prepare a molecular salt of succinic acid with (S)-(-)-α-methylbenzylamine, we have obtained the second polymorph of the monoammonium salt of succinic acid, NH·CHO. The crystal structure determination proves the structure of the ionic compound and the intimate role of the ammonium ion in the structure, which is compared to the earlier described polymorph.