Synthesis and characterization of heterobimetallic molybdenum and nickel complexes derived from polyfunctional disalicylaldehyde oxaloyldihydrazone

Heterobimetallic nickel and molybdenum complexes of the composition [Ni(L)MoO2(A)4]·nH2O (A = H2O (1), py (2), 2-pic (3), 3-pic (4), and 4-pic (5); n = 0, 2) and [Ni(L)(MoO2)(BB)2](BB = bpy (6) and (phen (7)) have been synthesized from the multidentate ligand disalicylaldehyde oxaloyldihydrazone (H4L) in methanol. The composition of the complexes has been established based on data obtained from elemental analyses, thermoanalytical, mass spectral and molecular weight studies. The probable structures of the complexes have been discussed in the light of molar conductance, magnetic moment data and electronic, EPR and infrared spectral studies. In all of the complexes, the dihydrazone is present in enol form and coordinates to the metal centre as a tetrabasic hexadentate ligand. All of the complexes are normal paramagnetic to the extent of two unpaired electrons per nickel atom. The μeff values for the complexes lying in the region 2.87–3.07 B.M. are consistent with the octahedral stereochemistry of nickel(II) in the heterobimetallic complexes. The EPR and electronic spectral data also support the distorted octahedral stereochemistry of the nickel(II) centre. Both nickel and molybdenum have octahedral geometry in the complexes.

► Heterobimetallic molybdenum and nickel complexes have been synthesized from disalicylaldehyde oxaloyldihydrazone.
► The dihydrazone coordinates to the metal centres in enol form as a tetrabasic hexadentate ligand.
► All of the complexes are monomeric and normal paramagnetic.
► MoO22+ binds to enolate oxygen atoms and nickel(II) binds to phenolate oxygen and azomethine nitrogen atoms.
► Both the molybdenum and nickel atoms have distorted octahedral structure in the complexes.