Trinuclear Cu(II) complex with tetrazolyl-pyridine units as a bridging ligand: synthesis, characterization and X-ray structure

Reaction of 5-(2-pyridyl)tetrazole with 1,3-dibromopropane afforded three regioisomeric multidentate ligands L1, L2 and L3 containing two tetradentate pyridyl/tetrazolyl units linked by a flexible propylene spacer. These compounds were fully characterized by IR, 1H and 13C NMR spectroscopy and elemental analysis. The crystal structure of L1 was determined. With Cu(II), L1 formed a trinuclear complex Cu3(L1)2Cl6. Its structure was determined crystallographically. In the complex, the three copper atoms are found to be in a strict linear arrangement, with the ligand bridging two adjacent copper atoms. The central copper ion is six-co-ordinated. The co-ordination spheres of the terminal copper atoms are distorted square pyramidal. Inter and intramolecular π,π-stacking interactions are observed in the free ligand and in complex 1.