KCS

Single crystals of fully dehydrated and fully Li⁺-exchanged Zeolite X (|Li₉₂|[Si₁₀₀Al₉₂O₃₈₄]-FAU) and partially Li⁺-exchanged Zeolite Y (|Li₆₄Na₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU) have been determined by single-crystal X-ray diffraction techniques at 100 K in the cubic space groups Fd3- (a = 24.663(1) Å) and Fd3 -m (a = 24.619(1) Å), respectively. The two Single-crystal structures were refined using all intensities to the final error indices (using only the 1179 and 554 reflections for which F_o > 4(F_o), respectively) R₁/R₂ = 0.0806/0.2596 and 0.0436/0.1602, respectively. In the structure of |Li₉₂|[Si₁₀₀Al₉₂O₃₈₄]-FAU, 92 Li⁺ ions per unit cell are located at three different crystallographic sites. The 32 Li⁺ ions at Li(I’) per unit cell are located at site I’ in the sodalite cavity opposite D6Rs (Li-O = 1.903(5) Å and O-Li-O = 117.9(3)°). The 32 Li⁺ions fill sites II opposite double 6-rings in the supercage (Li-O = 1.968(5) Å and O-Li-O = 118.4(3)°). The 28 Li⁺ ions at Li(III) per unit cell occupy the 96-fold positions at site III in the supercage (Li-O = 2.09(12) Å and O-Li-O = 98(8)°). In the structure of |Li₆₄Na₆|[Si₁₁₇Al₇₅O₃₈₄]-FAU, 64 Li⁺ and 6 Na⁺ions per unit cell are located at two and one different crystallographic sites, respectively. The 32 Li⁺ ions fill site I’ in the sodalite cavities on 3-fold axes opposite double 6-rings (Li-O = 1.918(4) Åand O-Li-O = 117.8(3)°), 32 Li⁺ ions fill site II opposite double 6-ring in the supercage (Li-O = 2.000(4) Å and O-Li-O = 117.4(3)°). The 6 Na⁺ ions occupy at site III’ (Na-O = 2.55(3) Åand O-Li-O = 79.3(10)°).