A novel copper diphosphonate complex Cu4(aedp)2(4,4′-bpy)(H2O)4 with three-dimensional framework structure

A novel copper organodiphosphonate complex containing a second ligand 4,4′-bipyridine (4,4′-bpy) based on 1-aminoethylidenediphosphonic acid (H₄aedp), Cu₄(aedp)₂(4,4′-bpy)(H₂O)₄ (1), has been synthesized under hydrothermal conditions. Complex 1 adopts a three-dimensional framework structure assembled from {Cu₄(aedp)₂(H₂O)₄} layers and 4,4′-bpy bridges. Each {Cu₄(aedp)₂(H₂O)₄} unit consists of three crystallographically distinct Cu atoms. The Cu(1) atom has a distorted square pyramidal geometry, whereas the Cu(2) and Cu(3) atoms have a distorted elongated tetragonal octahedral geometry. The magnetic studies indicate that complex 1 show typical antiferromagnetic behaviors at low temperature, which is attributed to the superexchange couplings between Cu(II) centers through μ-O bridge in the phosphonate layers. Crystal data for 1: triclinic, space group , a=8.0931(16), b=13.567(3), c=6.2185(12)Å, α=90.55(3), β=96.97(3), γ=78.50(3)°, V=664.1(2)ų, Z=2.