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)X2] 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)Br2] 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 C2-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)Cl2] 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 N6 environment of two mer-oriented tridentate ligands.