for an additional 4 hours at room temperature finally ligand 1 was synthesized by adding separate solutions of oxalyl chloride and compound 5 in tetrahydrofuran very slowly using a syringe pump this process is required to reduce other side reactions and maximize macrocycle production in fact the structure of 5 may be helpful to some extent in keeping the two amine groups close together which can easily react with oxalyl chloride to form the macrocycle during the reaction the macrocycle precipitates out from the solution and can be recovered just by simple filtrations washing with water was necessary to remove any triethylamine hydrochloride salt which co precipitates with the ligand during reaction the resulting product was transferred to a round bottom flask and 200 ml of diethyl ether added the mixture was sonicated for 15 minutes and then filtered the precipitate was collected and rinsed with additional ether to further purify the material the resulting product was dried for 12 hours under vacuum at 80 u00b0 c to yield the desired macrocyclic ligand 1 the 1 h nmr spectra for all the intermediates including the macrocycle were obtained and indicates the formation of the compounds after synthesizing the ligand 1 the fe complex 2 was developed ligand 1 was first deprotonated using a strong base and reacted with ferrous chloride in dry tetrahydrofuran more specifically 1 200 mg 0 61 mmol was dissolved in 30.