The system of hydrogen bonds in Ba2Re6Te8(CN)(6)center dot 12H(2)O: Simulation and NMR study

The crystal hydrate Ba2Re6Te8(CN)(6).12H(2)O whose structural fragments are the cluster anions [Re6Te8(CN)(6)](4-) is studied by H-1 NMR. In the tricl inic cell (space group P (1) over bar), the barium atoms coordinated by sir water molecules are united into the dimers [Ba.5H(2)O](2)(4+) by two bridg ing H2O molecules; the water molecules lying outside the coordination spher e of Ba are located in the structure channels running along the [001] direc tion. Diffusion of H2O molecules was found in the range of temperatures 100 degrees C below the temperature of intense dehydration of the crystal The structure of the water lattice of the compound is modeled by calculating Co ulomb interactions between hydrogen and surrounding atoms and analyzing the NMR spectra recorded under translational diffusion conditions for H2O. Hal f of the protons in H2O molecules are involved in the formation of hydrogen bonds whose lengths lie within 2.78-2.86 Angstrom (O-H...O) and 292-3.13 A ngstrom (O-H...N). The water lattice structure is preserved up to approxima te to 100 degrees C. The water subsystem is radically rearranged upon subse quent heating followed by partial dehydration of the crystal.