ZWITTERIONS IN CRYSTALLINE AMINOPHOSPHONIC ACIDS .2. CRYSTAL AND MOLECULAR-STRUCTURE OF 4-PYRIDYL-METHYLPHOSPHONIC ACID MONOHYDRATE

Crystal and molecular structure of the 4-pyridylmethylphosphonic acid monohydrate was determined by an X-ray analysis. Molecule of the title compound exists as a zwitterion. Negative charge is spread over the O 1-P-O3 fragment of the phosphonic group while the positive charge is d elocalized on the pyridyl ring. The crystal packing properties are inf luenced by presence of the water molecules in a crystal lattice. The l atters are involved in the extensive hydrogen bonds network. Crystal d ata: C6H8NO3P . H2O; M(r) = 191.1; crystal system: monoclinic; space g roup: P2(1)/n; cell dimensions: a = 8.158(1), b = 7.518(1), c = 13.528 (1) Angstrom, beta = 93.03(1)degrees, V = 828.5(5) Angstrom(3); z = 4; D-m = 1.51 (by flotation in aqueous KI solution), D-x = 1.53 Mgm(-3); room temperature; lambda(MoK alpha) = 0.71069 Angstrom; mu = 3.01 mm( -1); F(000) = 400; refinement on F-2 converged at the standard R = 0.0 35 (calculated for 1373 reflections with F-0 > 4 sigma(F-0)), R = 0.03 7 (calculated for all unique reflections) wR(2) = 0.099 and goodness o f fit S = 1.134.