The first organocopper tetrazole derivative: synthesis and characterization

1-(5-Amino-3-azapentyl) tetrazole dihydrochloride (HL center dot 2HCl) was prepared by heterocyclization of di-ethylenetriamine with triethyl orthoformate and sodium azide followed by treatment with potassium carbonate and hydrochloric acid. The reaction of CuCl2, HL center dot 2HCl and triethylamine (NEt3) in a molar ratio of 1 : 1 : 3 in water was found to generate a novel organometallic tetrazole derivative Cu2L2Cl2. This compound is present as a binuclear centrosymmetric molecular complex, in which C-deprotonated tetrazole L acts as a chelating ligand via the two amino N and tetrazole ring C coordination sites and the two copper atoms are linked together through two tetrazole ring N-4-C-5 bridges. This complex is the first organocopper tetrazole derivative. When the molar ratio of the reagents in the abovementioned reaction was changed to 1 : 2 : 2, the complex Cu(HL)(2)Cl-2 was formed along with Cu2L2Cl2. Pure Cu(HL)(2)Cl-2 was isolated after reaction of the reagents in a molar ratio of 1 : 3 : 6. The complex Cu(HL)(2)Cl-2 is present as a mononuclear molecular complex, with a chelating coordination mode of HL via the two amino N atoms only. Both complexes as well as HL center dot 2HCl were characterized by single-crystal X-ray analysis.