title: 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.
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, 2C(5)H(7)N(2)(+).C(7)H(10)N(2)O(6)P(2)(2-).2.4H(2)O, (I), and triammonium hydrogen [(5-methyl-2-pyridyl)aminomethylene]diphosphonate monohydrate, 3NH(4)(+).C(7)H(9)N(2)O(6)P(2)(3-).H(2)O, (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-H...O and N-H...O 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.
authors.affiliation: Department of Chemistry, Wrocław University of Technology, Wybrzeze Wyspiańskiego 27, 50-370 Wrocław, Poland. ewa.matczak-jon@pwr.wroc.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Matczak-Jon
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Slepokura
authors.forename: Paweł
authors.initials: P
authors.lastname: Kafarski
authors.forename: Izabela
authors.initials: I
authors.lastname: Skrzyńska
authors.forename: Marek
authors.initials: M
authors.lastname: Jon
mesh_terms: D015761:4-Aminopyridine / Q000737:chemistry*; D000641:Ammonia / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004164:Diphosphonates / Q000737:chemistry; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D063065:Organophosphonates / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012492:Salts; D013237:Stereoisomerism
chemical_list: C543554:((5-methyl-2-pyridinio)aminomethylene)diphosphonate dianion; D004164:Diphosphonates; D063065:Organophosphonates; D011725:Pyridines; D012492:Salts; D000641:Ammonia; D015761:4-Aminopyridine