Structure of hydrogeno bis (dihydrogeno diphosphonate) trithallium: T13H(H2CH2P2O6)2

T1₃H(H₂CH₂P₂O₆)₂ was found to be monoclinic B2/b, a = 10.736 (6) Å, b = 12.382 (7) Å, c = 11.527 (4) Å, γ = 106.11 (5)°, Z = 4. The structure was solved with MULTAN and refined to R(Fo) = 0.063 for 1500 reflections measured with MoKα radiation. This structure can be described as a succession, parallel to the (100) plane, of diphosphonate groups and thallium ions layers.Hydrogen bondings are found between the diphosphonate groups' layers. This bonding conduct to the formation of anionic group (H₂CH₂P₂O₆HH₂CH₂P₂O₆)³⁻ analogous to the (H₂P₂O₇HH₂P₂O₇)³⁻ complex anion.