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Organic Chemistry, Inorganic and nuclear chemistry
The reaction of 2-(2H-tetrazol-5-yl)pyridine (L1) with 1,6-dibromohexane results in formation of the isomers 2-(6′′-bromohexyl-(1-tetrazol-5-yl)pyridine (L2) and 2-(6′′-bromohexyl-(2-tetrazol-5-yl)pyridine (L3). Coordination reactions of L2 and L3 with CuCl2·2H2O, Co(SCN)2 and Fe(ClO4)2·H2O yielded the strongly coloured solids [Cu(II)(L2)Cl2]2 (1), [Cu(II)(L3)Cl2]2 (2), [Co(II)(L2)2(NCS)2] (3), [Co(II)(L3)2(NCS)2] (4), [Fe(II)(L2)2(H2O)2](ClO4)2 (5) and [Fe(II)(L3)2(H2O)2](ClO4)2 (6), containing high-spin metal centres for the Co(II) and Fe(II) compounds. X-ray crystal structures were obtained for complexes 1–5. In each complex, ligands L2 and L3 coordinate to the metal centre through the pyridyl N atom and the 1-N site of the tetrazole ring, and the pyridyl-tetrazole ligand remains planar in all cases except 3. Complexes 1 and 2 comprise a central Cu2Cl2 dimeric core with Cu(II) in an essentially square-pyramidal coordination environment. Complexes 3 and 4 contain Co(II) in a distorted octahedral coordination environment. In 3, the pyridyl and tetrazole rings of L2 are twisted with respect to each other and the complex adopts a puckered conformation in its equatorial plane. Complex 5 contains water molecules coordinated to Fe(II) in the axial sites, which form hydrogen bonds to the perchlorate counter anions.
Kelleher, F., Bond, A., Fleming, A., Gaire, J., McKee, V., and Sheridan, U. Coordination studies of copper(II), cobalt(II) and iron(II) with isomeric pyridyl-tetrazole ligands. Polyhedron, Volume 33, Issue 1, 9 February 2012, Pages 289–296. http://dx.doi.org/10.1016/j.poly.2011.11.038,