Preparation of novel silver borates by soft hydrothermal synthesis in sealed tubes: New representatives of larderellite and veatchite families

New silver-based representatives of the larderellite and veatchite families, Ag2B10O14(OH)4 center dot H2O (1) and Ag2B5O8(OH)center dot H2O (2) respectively, have been prepared using a soft hydrothermal synthetic approach inside a sealed silica tube. Both structures are built of the pentaborate groups yet exhibit various dimensionality: 2D for 1 and 1D for 2. The silver atoms in 1 exhibit noticeable anharmonicity approximated using Gram-Charlie approach. 1 was additionally characterized by thermal analysis, high-temperature X-ray powder diffraction and IR spectroscopy. Thermal expansion of 1 is strongly anisotropic (alpha 11 = 38, alpha 22 = -13, alpha 33 = 14 x 10-6 degrees C- 1) which is related with the hinge mechanism of the larderellite chains from corner-sharing pentaborate groups. Topology and complexity analysis of these compounds within the larderellite and veatchite families is presented.