Anti-electrostatic hydrogen-bonded tellurate dimers captured and stabilized by crystallization of a bis-iminoguanidinium salt

Anionic Te2O6(OH)44– dimers have been captured by crystallization of a hydrated salt of glyoxal-bis-iminoguanidinium (GBIG), and structurally characterized by single-crystal X-ray diffraction and vibrational spectroscopy. The crystal structure reveals anti-electrostatic hydrogen-bonded chains of Te2O6(OH)44– dimers, consisting of edge-sharing TeO6 octahedra, stabilized by hydrogen bonding from the GBIG cations and the water molecules included in the crystal. FTIR spectroscopy confirms the presence of TeO6 octahedra with characteristic Te–O stretching modes at 755 cm−1 and 689 cm−1, while the observed stretching mode at 3459 cm−1 confirms the presence of axially-bonded hydroxyl groups. Raman spectroscopy and DFT calculations confirm the presence of the Te2O6(OH)44– dimers in the crystalline phase and of the TeO(OH)5– monomers in solution.