Ab-initio structure determination of zeolite RUB-10 from low resolution X-ray powder diffraction data

Abstract

Abstract The ab-initio solution of the crystal structure of the zeolite material RUB-10 from X-ray powder diffraction data at 2 Å resolution is presented. Microcrystallinity and poor crystallinity are inherent properties of this material that could not be overcome by optimizing the synthesis conditions. RUB-10 is monoclinic with space group P21/a and a = 13.112(2) Å, b = 12.903(1) Å, c = 12.407(2) Å, β = 113.50(1)°, V = 1925 Å3, unit cell content: [Si32B4O72] [N(CH3)4]4. The general connectivity pattern of the silicate framework which belongs to the clathrasil family, was determined by introducing the relatively rigid building unit [Si5] in a Patterson search in the aristotype symmetry C2/m. With the help of framework models based on distance least-squares refinements, detailed information was obtained about the topology of the silicate framework, the Si/B ordering and the location of the template species. The structure of RUB-10 is completely new (structure type code RUT), and the two cage-like subunits found, [445462] and [44566581], have not yet been encountered in other porous structure types.