Tetrakis(μ‐guanidino­acetic acid‐κ2O:O′)­bis­[(nitrato‐κO)copper(II)]

The title compound, [Cu₂(NO₃)₂(C₃H₇N₃O₂)₄], forms a centrosymmetric dimer, with the two Cu²⁺ ions separated by 2.6525 (6) Å. The asymmetric unit contains a Cu atom coordinated to two guanidino­acetic acid ligands (via one carboxyl­ate O atom from each ligand) and to a nitrate group. The inversion centre in P generates the entire mol­ecule, in which each Cu atom is coordinated to four carboxyl­ate and to one nitrate O atom; ignoring the Cu—Cu separation, the geometry about each Cu atom is square pyramidal. The amino acid ligand is in the zwitterionic form. Strong N—H?O hydrogen bonds lead to a three‐dimensional supramolecular structure, in which the N?O distances are in the range 2.931 (4)–3.278 (3) Å, with N—H?O angles ranging from 128 to 170°.