Trinuclear nickel coordination complexes of phenanthrene-9,10-dione dioxime.

ABSTRACT: A trinuclear nickel complex of phenanthrene-9,10-dione dioxime (H2pqd), namely bis-[?2-9,10-bis-(oxido-imino)-phenanthrene]-bis-[?2-10-(oxido-imino)phenanthrene-9-one oxime](phenanthrene-9,10-dione dioxime)trinickel(II) toluene disolvate, [Ni3(C14H8N2O2)2(C14H9N2O2)2(C14H10N2O2)]·2C7H8, has been isolated and its crystal structure determined. This complex features three independent Ni(II) atoms that are arranged in a triangular fashion along with five supporting ligands. There are two square-planar Ni(II) atoms and a third pseudo-octa-hedral Ni(II) atom. While the square-planar Ni(II) atoms are stacked, there are no ligand bridges between them. Each square-planar Ni(II) atom, however, bridges with the pseudo-octa--hedral Ni(II) atom through Ni-N-O-Ni and Ni-O-Ni bonds. A fluorido-bor-ation reaction of the proton-bridged species gave the analogous complex bis-(?2-bis-{[10-(oxido-imino)-9,10-di-hydro-phenanthren-9-yl-idene]amino}di-fluorido-borato)(phenanthrene-9,10-dione dioxime)trinickel(II) dichloromethane trisolvate, [Ni3(C28H16BF2N4O2)4(C14H10N2O2)]·3CH2Cl2, which shows the same binding structure, but features a widened Ni-Ni inter-action between the square-planar Ni(II) atoms. The proton-bridged complex completes the macrocyclic coordination around the square-planar Ni(II) atoms by means of an O-H?O hydrogen bond. Both compounds feature O-H?N hydrogen bonds between the oxime and the N atoms attached to square-planar nickel atom. The nickel units show no direct inter-action with their nearest neighbors in the extended lattice. Two ?-stacking inter-actions between adjacent mol-ecules are found: one with a centroid-centroid distance of 3.886?(2)?Å and the other with a centroid-centroid distance of 4.256?(3)?Å. In the latter case, although not aromatic, the distance to the centroid of the central phenanthrene ring is shorter, with a distance of 3.528?(3)?Å. Toluene mol-ecules occupy the solvent channels that are oriented along the c axis. In the fluorido-boronate structure, the solvent (DCM) was too badly disordered to be modelled, so its contribution was removed using SQUEEZE [Spek (2015 ?). Acta Cryst. C71, 9-18].

SUBMITTER: Williams OM 

PROVIDER: S-EPMC4910314 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature