Direct Synthesis and Characterization of Copper(II) 1‐Phenyltetrazol‐5‐olates

The interaction of 1‐phenyl‐1,4‐dihydro‐5H‐tetrazol‐5‐one (Hpto) with ethylenediamine (en) and metallic copper in ethanol in the open air was found to yield molecular complexes [Cu(en)2(pto)2] (1) or [Cu2(en)2(EtOH)2(pto)4] (2) depending on the reagents ratio. Deprotonated tetrazol‐5‐one, i.e 1‐phenyltetrazol‐5‐olate anion (pto) acts as a monodentate ligand coordinated to the metal via the tetrazole ring N4 atom in mononuclear complex 1, and as a bridging ligand coordinated via the tetrazole ring N4 and N3 atoms in binuclear complex 2. The latter was found to be a paramagnet, with a very weak antiferromagnetic exchange interaction between copper ions.