Crystal structure and magnetic properties of copper formate anhydrate [α-Cu(HCOO)2]

The crystal structure of anhydrous copper formate α-Cu(HCOO)₂] has been refined from neutron powder data by the profile analysis technique at three different temperatures. Hydrogen atoms were located and refined with anisotropic temperature factors. The copper ion has a Jahn-Teller distorted tetragonal pyramidal coordination. Magnetic measurements showed a paramagnetic behaviour in the temperature region 10–300 K. The positive Curie temperature of θ_{c = 9.8(3}) suggests, however, a ferromagnetic ordering at low temperatures.