CRYSTAL AND MOLECULAR STRUCTURE OF BIS(O-PHENYLENEDIAMINO)NICKEL NI[C6H4(NH)2]2

The crystal and molecular structure of bis(o-phenylenediamino)nickel, Ni[C6H4(NH)2]2, has been determined by singlecrystal X-ray diffraction techniques. The crystals are monoclinic (P21/c) with a = 5.845 ± 0.020 Å, b — 7.485 ± 0.026 Å, c = 25.27 ± 0.09 Å, 3 = 90° 10′ ± 10′, and Z = 4. The observed and calculated densities are, respectively, 1.62 ± 0.02 and 1.64 ± 0.01 g/cm3. The structure was refined by least-squares methods to a conventional R factor of 11.1% for 792 nonzero independent reflections collected at room temperature by film techniques. The nickel atom is four-coordinate in the monomeric, planar Ni[C6H4(NH)2]2 molecule. The average Ni–N bond length of 1.832 ± 0.011 Å is one of the shortest yet observed, and the bond lengths in the chelate rings (N-C, 1.38 ± 0.02; C-C, 1.41 ± 0.02 Å) indicate substantial delocalization of the π bonds. The observed structure seems inconsistent with a formulation based on nickel(IV), but it supports the assignment of this compound as the neutral central member of a family of complexes which are interrelated by electron-transfer reactions. © 1968, American Chemical Society. All rights reserved.