Metal complexes as ligands. Part 12. Synthesis and X-ray crystal structure of a hexanuclear nickel(II) complex based on two isosceles trinuclear components with imidazolate bridges

Abstract

The new ligand H₂L, derived from 5-chloro-2-hydroxybenzophenone, o-phenylenediamine, and imidazole-2-carbaldehyde, forms an insoluble, apparently polymeric nickel(II) complex, which can dissociate and act as a monodentate ligand via a ring nitrogen donor. It forms a 2:1 adduct with nickel hexafluoroacetylacetonate, Ni(hfacac)₂, with a toluene molecule in the hollow of the V-shaped trinuclear fragment. The central nickel is octahedral with two hfacac ligands and two cis-bonded NiL complex ligands, to form an isosceles triangle of nickel atoms, of dimensions 5.754 × 5.783 × 6.407 Å. The overall structure is hexanuclear, consisting of two trinuclear subunits joined by two weak (2.908 Å) Ni–O links between NiL complex ligands. [(NiL)₂Ni(hfacac)₂]₂·2C₆H₅Me crystallizes in space group P with a= 16.044(6), b= 15.939(4), c= 14.971(9)Å, α= 78.33(4), β= 72.09(5), γ= 63.56(6)°, and Z= 1; R= 0.065 for 4 660 reflections.