The cover picture shows sections of the crystal structures of Cu[µ2‐OOC(CH2)PO3H]·2H2O (1) and Cu1.5[µ3‐OOC(CH2)PO3]·5H2O (2).
(1) is a layer‐like coordination polymer, which due to its ‐PO3H group can be regarded as the protonated form of a cation exchanger. The density of negative charge of the deprotonated layers would be similar to that of layered silicate minerals. The diffuse reflectance UV/Vis spectrum of powdered (1) can be fitted well by three Gaussian curves.
(2) has polyanionic chains with {Cu(H2O)[OOC(CH2)PO3]}nn– composition.
Hydrated Cu2+ cations are accommodated between the chains as counter ions and therefore (2) can be regarded as a chain‐like cation exchanger loaded with [Cu(H2O)6]2+. (2) shows antiferromagnetic coupling at low temperature obviously caused by a super‐superexchange mechanism.
More details are discussed in the article by R. Köferstein, M. Arnold, and C. Robl on page 276 ff.