Compounds 1 and 2 exhibit structural changes in the symmetry
of the crystal lattice with small differences in local geometries,
apparently resulting from the distinct anions used during their
preparation [25]. However, both compounds have the same (4,4)
topology. Compound 1 is a 2D layer based on trinuclear formatobridged secondary building units while compound 2 is a 2D layer
assembled from analogous dinuclear formato-bridged secondary
building units (Schemes 1 A and B). The ClO4 anions in 1 are located in the lattice cavities whereas the NO3 anions in 2 are coordinated to the copper(II) centres.