Metal-organodiphosphonate chemistry: Hydrothermal syntheses and structures of Ca(II) coordination polymers with xylyldiphosphonate ligands

Hydrothermal reactions of Ca(NO3)(2)center dot 4H(2)O and the appropriate xylyldiphosphonic acid provided crystals of [Ca(p-C8H8P2O6H2)(OH2)(3)](n) (1), [Ca(m-C8H8P2O6H2)(OH2)(2)](n) (2), and [Ca(omicron-C8H8P2O6H2)(OH2)](n) (3). The juxtaposition of phosphonate donor groups on the xylyl-diphosphonate linkers is a major structural determinant. Thus, the structure of [Ca(p-C8H8P2O6H2)(OH2)(3)](n) (1) is three dimensional, while [Ca(m-C8H8P2O6H2)(OH2)(2)](n) (2) and [Ca(omicron-C8H8P2O6H2)(OH2)](n) (3) exhibit reduced dimensionalities, one-and two-dimensional, respectively. The structures exhibit variable coordination numbers, as well as variable numbers of coordinated water molecules. In addition, hydrogen bonding plays an important role in the structural chemistry of these materials. (C) 2015 Elsevier B.V. All rights reserved.