Polymerisation of a Cu(II) dimer into 1D chains using high pressure

Long intermolecular interactions are converted into covalent bonds when the complex [Cu-2(OH)(citrate)(Guanidine)2](-) is exposed to a pressure of 2.9 GPa; the coordination of the Cu centres changes from [4 + 1] to [4 + 2], but on increasing the pressure to 4.2 GPa some of the Cu centres become [4 + 1]-coordinate again