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 perchlora te salts of its copper(I) and copper(II) complexes. respectively, are reported. The structures of the free ligand and of the copper(II) comp lex have been determined by three-dimensional X-ray diffraction method s. 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)-d egrees. The structure has been refined to a final value for the crysta llographic R factor of 0.0486 based on 1365 observed independent refle ctions. The ligand adopts a relatively extended conformation in the cr ystals. the torsion angles around the nominally single C-C bonds linki ng the phen and pyrazole rings being 163.6 and 164.4-degrees, respecti vely. The copper(II) complex [Cu(bpmp)(H2O)](ClO4)2 crystallizes in th e space group P1BAR of the triclinic system with two molecules in a ce ll 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)-degr ees, 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 35 60 observed independent reflections. The cation adopts a five-coordina te geometry, the coordination being provided by two phen nitrogen atom s [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 de scribed as trigonal bipyramidal, with one phenanthroline and one pyraz olyl nitrogen atom axial while the other phenanthroline and pyrazolyl nitrogen atoms and the water ligand are equatorial. The copper(II) com plex [Cu(bpmp)(H2O)]2+ exhibits a reversible wave at 0.037 V vs Ag/AgC l, attributable to the [Cu(bpmp)(H2O)]2+/+ couple.