Abstract
The molecular and crystal structures of two α-aminophosphonic acids with small substituents at the α-carbon atom—(1-aminoethyl)phosphonic acid 1 and (1-amino-2,2-dimethylpropyl)phosphonic acid monohydrate 4—were determined by single-crystal X-ray diffraction studies. The crystal structures provide important information on the hydrogen bonding properties of α-aminophosphonic acids. In the crystal, the molecules are linked together by strong O‒H···O hydrogen bonds, forming chains which are contorted to helix-like structures, in the case of the hydrate, by a cooperative effect of the water molecules. The chains are linked together by weaker N‒H···N hydrogen bonds to form the crystal.
GRAPHICAL ABSTRACT
![](/cms/asset/c57095dc-47fa-496a-b9e7-1325ea772581/gpss_a_597803_o_uf0001.gif)
Acknowledgments
This investigation has been financially supported by Institutional Strategy of the Excellence Initiative at LMU Munich—LMUexcellent.