Syntheses, crystal structures and magnetic properties of transition metal compounds with the 3-pyridylphosphonato ligand

Silver(i) pyridylphosphonates - synthesis, structure, stability and light-insensitivity investigation

Two silver(i) complexes, {[Ag7(2-pypo)3(NO3)]} n (1) and [Ag(3-pypoH)(3-pypoH2)] (2) (pypoH2 - pyridylphosphonic acid) were prepared and characterized by relevant methods in the solid state (elemental, spectral, thermal and structural analysis). Typical argentophilic interactions were observed in complex 1. The synthesized Ag(i) complexes were tested toward reduction to silver(0) using short wavelength UV-radiation and they revealed remarkable light-insensitivity in comparison to silver nitrate. SEM experiments were performed to observe the reduction of silver after the UV-light exposure of the samples. Light-insensitivity with the examined thermal stability and insolubility of the new complexes demonstrates their high potential to be used as light-insensitive materials in medical devices.

Synthesis, structural characterization and computational studies of catena-poly[chlorido[μ3-(pyridin-1-ium-3-yl)phosphonato-κ3O:O':O'']zinc(II)]

Coordination polymers are constructed from two basic components, namely metal ions, or metal-ion clusters, and bridging organic ligands. Their structures may also contain other auxiliary components, such as blocking ligands, counter-ions and nonbonding guest or template molecules. The choice or design of a suitable linker is essential. The new title zinc(II) coordination polymer, [Zn(C₅H₅NO₃P)Cl]_n, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction and vibrational spectroscopy (FT-IR and FT-Raman). Additionally, computational methods have been applied to derive quantitative information about interactions present in the solid state. The compound crystallizes in the monoclinic space group C2/c. The four-coordinated Zn^II cation is in a distorted tetrahedral environment, formed by three phosphonate O atoms from three different (pyridin-1-ium-3-yl)phosphonate ligands and one chloride anion. The Zn^II ions are extended by phosphonate ligands to generate a ladder chain along the [001] direction. Adjacent ladders are held together via N-H...O hydrogen bonds and offset face-to-face π-π stacking interactions, forming a three-dimensional supramolecular network with channels. As calculated, the interaction energy between the neighbouring ladders is -115.2 kJ mol^-1. In turn, the cohesive energy evaluated per asymmetric unit-equivalent fragment of a polymeric chain in the crystal structure is -205.4 kJ mol^-1. This latter value reflects the numerous hydrogen bonds stabilizing the three-dimensional packing of the coordination chains.