Synthesis and Structure Determination of a New Microporous Zeolite with Large Cavities Connected by Small Pores

A new small-pore germanosilicate zeolite, named as ITQ-49, has been synthesized using a new ditetraalkylphosphonium dication as an organic structure-directing agent, and its structure has been solved by direct methods applied to the powder X-ray diffraction pattern of the calcined solid. This new zeolite crystallizes in the space group <i>Immm</i> with cell parameters <i>a</i> = 19.6007(8) Å, <i>b</i> = 18.3274(7) Å, and <i>c</i> = 16.5335(6) Å. The pore topology of ITQ-49 consists of large, nonspherical cavities that are connected to each other through small eight-membered-ring windows, resulting in a unidirectional small-pore zeolite that has a relatively large adsorption capacity. Also, ITQ-49 contains double four-membered-ring units where Ge is preferentially located, and fluoride anions are placed inside these units