SYNTHESIS AND CHARACTERIZATION OF THE MULTIDENTATE LIGAND 2,9-BIS(N-PYRAZOLYLMETHYL)-1,10-PHENANTHROLINE (BPMP) AND ITS COPPER(I) AND COPPER(II) COMPLEXES

The synthesis of the novel nitrogen ligand 2,9-bis(N-pyrazolylmethyl)-1,10-phen (bpmp), C20H16N6, and of the tetrafluoroborate and perchlorate salts of its copper(I) and copper(II) complexes. respectively, are reported. The structures of the free ligand and of the copper(II) complex have been determined by three-dimensional X-ray diffraction methods. The ligand crystallizes in the space group P2(1) of the monoclinic system with two molecules in a cell of dimensions a = 5979(2) angstrom, b = 9.127(2) angstrom, c = 15.637(3) angstrom, and beta = 98.59(3)-degrees. The structure has been refined to a final value for the crystallographic R factor of 0.0486 based on 1365 observed independent reflections. The ligand adopts a relatively extended conformation in the crystals. the torsion angles around the nominally single C-C bonds linking the phen and pyrazole rings being 163.6 and 164.4-degrees, respectively. The copper(II) complex [Cu(bpmp)(H2O)](ClO4)2 crystallizes in the space group P1BAR of the triclinic system with two molecules in a cell of dimensions a = 8.6040(10) angstrom, b = 10.499(2) angstrom, c = 13.405(3) angstrom, alpha = 89.080(10)-degrees, beta = 80.040(10)-degrees, and gamma = 84.380(10)-degrees. The structure has been refined to a final value for the crystallographic R factor of 0.0490 based on 3560 observed independent reflections. The cation adopts a five-coordinate geometry, the coordination being provided by two phen nitrogen atoms [N(1) and N(2)] and two pyrazole nitrogen atoms [N(3) and N(4)] from the ligand and by a water molecule. The geometry at copper is best described as trigonal bipyramidal, with one phenanthroline and one pyrazolyl nitrogen atom axial while the other phenanthroline and pyrazolyl nitrogen atoms and the water ligand are equatorial. The copper(II) complex [Cu(bpmp)(H2O)]2+ exhibits a reversible wave at 0.037 V vs Ag/AgCl, attributable to the [Cu(bpmp)(H2O)]2+/+ couple.