Structural investigation of the nickel 3-methylglutarate from powder diffraction demonstrating adaptability of the inorganic skeleton of MIL-77

Abstract

Ni20[(C6H8O4)20(H2O)8]∙33H2O, a new nickel(II) 3-methylglutarate, was prepared hydrothermally (180 °C, 48 h, autogenous pressure) from a 1:1.5:2:180 mixture of nickel (II) sulphate hexahydrate, 3-methylglutaric acid, sodium hydroxide, and water. It crystallizes in the cubic system (space group P4332, Z=1) with a=16.8488(5) Å and V=4783.1(4) Å3. Its structure was solved from conventional X-ray powder diffraction data. It presents a three-dimensional network of edge-sharing nickel octahedra, lined by deprotonated organic anions. This remarkable oxide network with corrugated 20-membered rings is constructed from homochiral helices. The rings intersect each other to generate large crossing channels full of water along [111].