Anionic clays as hosts for anchored synthesis: Interlayer bromination of maleate and fumarate ions in nickel–zinc layered hydroxy double salt

Anionic clay-like nickel zinc hydroxyacetate, Ni₃Zn₂(OH)₈(OAc)₂·2H₂O was ion exchanged with maleate and fumarate ions. While the maleate enters as monoanion, fumarate enters as dianion. Also these anions take up different orientations in the interlayer region. The intercalated organic species could be reacted with bromine water in such a way that the brominated product remains intercalated making the reaction a true intracrystalline reaction. The stereochemistry of the reaction of the intercalated fumarate was identical to that of the free fumarate ion – both yielding only the anti addition product. While free maleate ion yielded only the anti addition product, the intercalated maleate ion yielded a small percentage of the syn addition product along with the anti addition product. The organic products could be quantitatively recovered by anion exchange with oxalate ions.