Synthesis, Structure, Thermal Decomposition and Computational Calculation of Heterodinuclear NiII - ZnII Complexes

Mononuclear NiL complex was prepared by the use of bis-N,N'-salicylidene-1,3-propanediamine and Ni(II) salts. NiL was treated with ZnBr2 and pyrazole and 3,5-lutidine coligands in a dioxane medium to prepare the following diheteronuclear complexes: [NiL·ZnBr2·(pyrazole)2] and [NiL·ZnBr2·(3,5-lutidine)2]. The complexes were characterized by elemental analysis, TG, IR and mass spectrometry. The effects of heterocyclic one- and two- nitrogen atoms containing co-ligands were also examined. Theoretical formation enthalpies, dipole moments and the relative levels of HOMO and LUMO energies were determined by the use of Gaussian09 program. The occupancy levels of the atomic orbitals were determined by the NBO analysis of Gaussian09. The effect of pyrazole and lutidine upon the complex formation was evaluated by the use of X-ray diffraction, TG and theoretical calculations. NiL complex with lutidine forms a square pyramidal conformation since lutidine is a much stronger coligand than pyrazole.