Three new, isostructural methylenediphosphonates of molybdenum, A[MoO2(O3PCH2PO3H)] (A = Rb (1), NH4 (2) and Tl (3)) have been synthesized by hydrothermal method and structurally characterised by X-ray diffraction and spectroscopic techniques. These compounds crystallize in monoclinic space group,P21/c with Z = 4 and consist of [MoO2(O3PCH2PO3H)]-anionic layers interleaved with A+ ions.
