Temperature controlled formation of polar copper phosphonates showing large dielectric anisotropy and a dehydration-induced switch from ferromagnetic to antiferromagnetic interactions

The polar compound Cu3(2-cpp)2(H2O)5 (1) converts into non-polar Cu3(2-cpp)2(H2O)2 (2) and Cu3(2-cpp)2 (3), accompanied by a switch from ferromagnetic in 1 to antiferromagnetic interactions in 2 and 3.