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 equation M(OH)2+xH+→[M(OH)2-x(H2O)x]x+. As in the LDHs, charge balance is restored by the incorporation of anions in the interlayer region