Syntheses and structures of two ammonium zinc gallophosphates: Analcime and paracelsian analogs

Two ammonium zinc gallophosphates (I) (NH?)16 [Zn16Ga8P24O96] and (II) (NH4 )(4)[Zn4Ga4P8O32] were hydrothermally synthesized and characterized using s ingle crystal X-ray diffraction. The (I) (NH4)(16)[Zn16Ga8P24O96] crystalli zes in a cubic I2(1)3 space group (a = 13.456(1) Angstrom, V = 2436.5(5) An gstrom (3), R (on F) = 2.47%, R-w (on F) = 2.48%). It has a zeolite analcim e topology with distorted eight-member ring channels. Zn and Ga atoms share the same crystallographic site with a partial occupancy of Zn/Ga = 0.67/0. 33. Ammonium ions lie on the three-fold crystallographic axes and compensat e for negatively charged framework. The second compound (II) (NH4)(4)[Zn4Ga 4P8O32] has a monoclinic symmetry (P2(1)/a, a = 9.406(1) Angstrom, b = 9:88 1(1) Angstrom, c = 8.612(1) Angstrom, beta = 90.58(1)degrees, R (on F)= 2.7 %, R-w (on F)= 3.0%). It is isostructural with a feldspar paracelsian. Zinc and gallium occupy two crystallographic sites with a partial occupancy of Zn(1)/Ga(1) = 0.53(6)/0.47(6) and Zn(2)/Ga(2) = 0.47(6)/0.53(6). Ammonium i ons lie in the elliptical eight-member ring openings of the three-dimension al framework. (C) 2001 Academic Press.