Structure cristalline du tétramétaphosphate de nickel-ammonium heptahydraté: Ni(NH 4) 2P 4O 12 · 7H 2O

Abstract

Nickel-ammonium tetrametaphosphate, Ni(NH 4) 2P 4O 12 · 7H 2O is triclinic with a = 13.841(3); b = 9.621(5); c = 7.482(2)Å; α = 98.05(4); β = 97.25(4); γ = 103.01(4)°; M = 536.59; V = 947.9Å 3; Z = 2; D x = 1.879 g cm −3; μ = 14.524 cm −1, and space group P 1 . The crystal structure was solved using 1661 independent reflections measured on a single-crystal diffractometer (Mo Kα). The final R value is 0.056. The two crystallographic independent nickel atoms Ni(1) and Ni(2) are octahedrally coordinated: Ni(1) by four oxygen atoms and two water molecules, Ni(2) by six water molecules. Ni(1), closely connected to two P 4O 12 rings, forms a complex anion [Ni(P 4O 12) 2(H 2O) 2] 6− which is associated to ammonium polyhedra and [Ni(H 2O) 6] 2+ octahedra. Another interesting feature of this atomic arrangement is the presence of a large channel (10 × 4) Å 2 parallel to the c axis. The internal surface of this channel is covered by six zeolitic water molecules.