Syntheses and Characterization of 1,4-Phenylenebisphosphonates, A[HO<inf>3</inf>PC<inf>6</inf>H<inf>4</inf>PO<inf>3</inf>H<inf>2</inf>] (A = Li, K, Rb, Cs, Tl, Ag and NH<inf>4</inf>) and Crystal Structure of 1,4-Phenylenebisphosphonic Acid

Seven 1,4-phenylenebisphosphonates of monovalent ions, A(HO3PC6H4PO3H2) (A = Li, K, Rb, Cs, Tl, Ag and NH4), were synthesized and characterized by single-crystal X-ray diffraction, spectroscopic and thermal methods. These compounds and the reported sodium analogue have four structure types. The sodium compound, one-dimensional lithium compound and pillared-layered cesium compounds have different structure types, whereas the potassium, rubidium, thallium, ammonium and silver compounds have a pillared ladder-like structure. They undergo initial thermal decomposition in the range of 120-270 °C. Moreover, the single crystal X-ray structure of 1,4-phenylenebisphosphonic acid was determined.