*2.4. Catalysis Protocol*

For the catalytic assays, fresh solutions of urea (60 mM in water) and of the complexes (1.6 mM in dichloromethane (DCM)) were prepared.

The catalytic assays were performed by diluting 50 μL of the solution containing the complex into 850 μL of the reaction solvent (methanol, acetonitrile, and dimethylsulfoxide, tetrahydrofuran, and ethanol). The reaction typically started by the addition of the urea solution (100 μL). Vigorous stirring was maintained over the course of the reaction. Aliquots of 100 μL of the reaction were taken after 5, 10, 20, 30, 40, 60, 120, 240 and 480 s of reaction. These aliquots were analyzed by the Berthelot method to quantify the ammonia content. The reaction temperature was kept at 36 ◦C. All reactions were performed in triplicate.

For each of the catalytic protocols, a control experiment was also performed without the complexes and the blank was subtracted from the catalytic measurements.

The amount of water in the medium, when increasing amount of urea concentrations were employed, were 10, 20, 30 and 40%, respectively, to the urea concentrations of 5.2, 10.4, 15.6 and 20.4 mM (except in acetonitrile, in which urea 20.4 mM was also employed).
