A desamidination process forming a novel guanidine derivative during the complexation between copper(II) and guanidinoacetic acid

A novel trianionic disubstituted guanidine, (1N-carboxymethylguanidino)hydroxyacetic acid-C5H6N3O5), oag3−, has been formed through a desamidination process occurred during copper(II) complexation with guanidinoacetic acid, C3H7N3O2 (Gaa), which produced [Cu2(oag)(Gaa)(H2O)]NO3 · 2H2O (1). A proposal mechanism of formation of 1 is presented based on the low temperature electron paramagnetic resonance and previous potentiometric studies, which have indicated the presence of CuH2Gaa as the precursor species.