Investigating substituent effects on the electronic structure of nickel alpha-diimine complexes.

摘要

alpha-Diimine (or) 1,4-diaza-1,3-butadiene (DAB) are neutral bidentate ligands and exhibit versatile coordination behavior with various transition and main group metals. These alpha-diimine ligands can be conveniently prepared by condensation reactions involving glyoxals, alpha-ketoaldehydes or diketones with primary alkyl or aryl amines (RNH2). The group 10 complexes of alpha-diimine have attracted considerable interest in recent time as a function of potential catalyst for the polymerization reactions. Over the years several Ni and Pd complexes of alpha-diimine have been prepared and test for the polymerization activity and showed promising activity in olefin polymerization reactions. The systematic electronic structure investigation on these complexes, by altering substituents on the ligand back-done has never been carried out. In this context, we are interested in investigating electronic effect on nickel alpha-diimine ligands of the type NiCl2[ArN=C(R)C(R)=NAr] (1 R = H, 2 R = Me, 3 R = Ph, 4 R = C6H4-p-OMe, 5 R = C6H4-p-NMe2, 6 R = C6H4-p-CF3, 7 R = An), where the substituents varied from electronic donating to electron withdrawing groups. Complexes 1-7 are geometry optimized using density function theory. Finally to correlate with the experimental values, attempts were made towards synthesizing these complexes.