Synthesis, characterization and protonation reaction of copper and palladium complexes bearing nitrite ligands in O,O-bidentate and N-monodentate bonding fashions

► Compound 3 has the nitrite ligand in an O,O-bidentate mode. ► Protonation of 3 releases NO gas. ► Compound 5 has the nitrite ligand in an N-monodentate mode. ► Protonation of 5 releases nitrous acid. ► Compound 5 shows hemilabile coordination properties.