Acta Crystallographica Section C

Crystal Structure Communications

Volume 65, Part 6 (June 2009)

organic compounds

tr3053 scheme

Acta Cryst. (2009). C65, o261-o266 [ doi:10.1107/S0108270109010683 ]

Conformational isomers of the [(5-methyl-2-pyridinio)aminomethylene]diphosphonate dianion and [(5-methyl-2-pyridyl)aminomethylene]diphosphonate trianion in salts with 4-aminopyridine and ammonia

E. Matczak-Jon, K. Slepokura, P. Kafarski, I. Skrzynska and M. Jon

Abstract: The crystal structures of two salts, products of the reactions between [(5-methyl-2-pyridyl)aminomethylene]bis(phosphonic acid) and 4-aminopyridine or ammonia, namely bis(4-aminopyridinium) hydrogen [(5-methyl-2-pyridinio)aminomethylene]diphosphonate 2.4-hydrate, 2C₅H₇N₂⁺·C₇H₁₀N₂O₆P₂^2-·2.4H₂O, (I), and triammonium hydrogen [(5-methyl-2-pyridyl)aminomethylene]diphosphonate monohydrate, 3NH₄⁺·C₇H₉N₂O₆P₂^3-·H₂O, (II), have been determined. In (I), the Z configuration of the ring N-C and amino N-H bonds of the bisphosphonate dianion with respect to the C_ring-N_amino bond is consistent with that of the parent zwitterion. Removing the H atom from the pyridyl N atom results in the opposite E configuration of the bisphosphonate trianion in (II). Compound (I) exhibits a three-dimensional hydrogen-bonded network, in which 4-aminopyridinium cations and water molecules are joined to ribbons composed of anionic dimers linked by O-HO and N-HO hydrogen bonds. The supramolecular motif resulting from a combination of these three interactions is a common phenomenon in crystals of all of the Z-isomeric zwitterions of 4- and 5-substituted (2-pyridylaminomethylene)bis(phosphonic acid)s studied to date. In (II), ammonium cations and water molecules are linked to chains of trianions, resulting in the formation of double layers.

Formula: 2C₅H₇N₂⁺·C₇H₁₀N₂O₆P₂^2-·2.4H₂O and 3NH₄⁺·C₇H₉N₂O₆P₂^3-·H₂O


	Structure factor file (CIF format) (331.0 kbytes) [ doi:10.1107/S0108270109010683/tr3053Isup2.hkl ] Contains datablock I

	Structure factor file (CIF format) (333.2 kbytes) [ doi:10.1107/S0108270109010683/tr3053IIsup3.hkl ] Contains datablock II

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