On the Existence of Hydrotalcite-Like Phases in the Absence of Trivalent Cations

α-Hydroxides of nickel(II) and cobalt(II) are hydrotalcite-like phases, possessing a layered double hydroxide (LDH) structure even though there are no trivalent cations in the lattice. While the LDHs acquire a positive charge on the hydroxide layers by the incorporation of trivalent cations, we suggest that the α-hydroxides acquire a positive charge by partial protonation of the hydroxyl ions according to the equationM(OH)2+xH+→[M(OH)2-x(H 2O)x]x+.As in the LDHs, charge balance is restored by the incorporation of anions in the interlayer region. © 1997 Academic Press