Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel): Elaboration via hydrolysis in polyol medium and comparative study

Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel) have be en prepared by a new route belonging to the chimie douce method. This novel method involves the hydrolysis, in polyol medium, of in situ-formed comple xes supposed to be alkoxyacetates. These layered hydroxide metal acetates p resent poorly ordered character, and their X-ray patterns have features typ ical of lamellar compounds with turbostratic disorder. Their chemical formu la was established to be M(OH)(2-x)(CH3COO)(x). nH(2)O with (x, n) = (0.42, 0.31), (0.38, 0.53), and (0.40, 0.63) for Zn, Co, and Ni, respectively. Th e 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 s tructure, in which cations are located in both octahedral and tetrahedral s ites. 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 pro cess for LHS-Ni and Co, whereas it is a destructive process in the case of LHS-Zn.