Layered Hydroxide Metal Acetates (Metal = Zinc, Cobalt, and Nickel): Elaboration via Hydrolysis in Polyol Medium and Comparative Study

Abstract

Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel) have been prepared by a new route belonging to the chimie douce method. This novel method involves the hydrolysis, in polyol medium, of in situ-formed complexes supposed to be alkoxyacetates. These layered hydroxide metal acetates present poorly ordered character, and their X-ray patterns have features typical of lamellar compounds with turbostratic disorder. Their chemical formula was established to be M(OH)2-x(CH3COO)x·nH2O with (x, n) = (0.42, 0.31), (0.38, 0.53), and (0.40, 0.63) for Zn, Co, and Ni, respectively. The layered hydroxide nickel acetate has a classical brucite structure with a random substitution of some hydroxyl groups by acetate groups. The layered hydroxide zinc and cobalt acetates are isomorphous with the hydrozincite structure, in which cations are located in both octahedral and tetrahedral sites. The acetate anion behaves as a unidentate ligand in LHS−Ni and LHS−Co, where LHS indicates layered hydroxide salt, and is intercalated as a free anion in the zinc compound. The dehydration is a reversible topotactic process for LHS−Ni and Co, whereas it is a destructive process in the case of LHS−Zn.