Conformations and resulting hydrogen-bonded networks of hydrogen {phosphono[(pyridin-1-ium-3-yl)amino]methyl}phosphonate and related 2-chloro and 6-chloro derivatives

Acta Cryst. (2011). C67, o450-o456 (http://doi.org/g3g)

The arrangement of the zwitterions in hydrogen {phosphono[(pyridin-1-ium-3-yl)amino]methyl}phosphonate monohydrate (pro-E) within the ribbons along the b axis.

The crystal structures of the two conformational isomers of the title compound, pro-E as the monohydrate and pro-Z in an anhydrous form, and the related 2-chloro (pro-E) and 6-chloro (pro-Z) derivatives are described. Chain-chain interactions involving phosphono (-PO₃H₂) and phosphonate (-PO₃H-) groups are dominant in determining the crystal packing in all four compounds.