Studies on clathrasils. IX*

Abstract

AbstractDeca-dodecasil 3R, 120 SiO2· 6M10· 9M12· 6M19with M12= N2and M19= C10NH17(1-aminoadamantane), crystallizes in space groupR[unk]mwitha= 13.860(3) Å andc= 40.891(8) Å. Its crystal structure is built by corner-sharing [SiO4] tetrahedra. The tetrahedra are connected to pseudohexagonal layers of face-sharing pentagonal dodecahedra ([512] cages). These layers are stacked in ABCABC sequence and interconnected by additional [SiO4] tetrahedra which form six-membered rings between the layers. Thus two new types of cage arise, another small decahedron, [435661] cage and a large 19-hedron, [435126183] cage, the latter housing the 1-aminoadamantane guest molecule.The 19-hedra are interconnected through 8-membered rings (pore width 4.5 Å), forming a two-dimensional pore system between the dodecahedral layers. Untreated deca-dodecasil 3 R is a member of the clathrasil family because the guest molecules trapped during synthesis are too large to pass through the 8-membered rings of the 19-hedra. However, on thermal treatment of deca-dodecasil 3 R the guest molecules are decomposed and the fragments are driven out of the cages, transforming the clathrasil to a phase possessing zeolitic properties.