Copper(II) compounds of the planar-tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine

The tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine (dPzPy) renders coordination compounds with halide, nitrate and tetrafluoroborate salts of copper. The complexes, which have the form [Cu(dPzPy)X-2] with X = Br and Cl, [Cu(dPzPy)(NO3)(2)](H2O), and [Cu(dPzPy)(2)](BF4)(SiF6)(0.5)(MeOH)(3) have been characterized by elemental analysis and by IR, EPR and ligand field spectroscopy. The single-crystal X-ray structure of [Cu(C11H9N5)Br-2] shows the copper(II) ion to be coordinated by three N atoms of 2,6-bis(pyrazol-3-yl)pyridine and two bromides in a geometry exactly in between a trigonal-bipyramid and a square-pyramid. Each molecule lies on a crystallographic C-2-symmetry axis. They are coupled to one another by a two-dimensional network through N-H to Br hydrogen bonds. The crystal structure of [Cu(C11H9N5)Cl-2] is analogous to the bromide. The single-crystal X-ray structure of [Cu(dPzPy)(2)](BF4)(SiF6)(0.5)(MeOH)(3) shows the copper ion to be in a Jahn-Teller distorted octahedral N-6 environment of two mer-oriented tridentate ligands. (C) 2002 Elsevier Science B.V. All rights reserved.