Bulky 2,6-Dibenzhydryl-4-methylaniline Derived Schiff Base Complexes of Pd(II), Cu(II) and Co(II) as Efficient Catalysts for Suzuki Coupling and Alcohol Oxidation Reactions

Bulky 2,6-dibenzhydryl-4-methylaniline reacts with 2-hydroxybenzaldehyde or 2-pyridinecaboxyaldehyde to form [N,O^-] and [N,N] donor ligands, 2-(((2,6-dibenzhydryl-4-methylphenyl)imino)methyl)phenol (L¹) and N-(2,6-dibenzhydryl-4-methylphenyl)-1-(pyridin-2-yl)methanimine (L²), respectively. Schiff bases, L¹ and L² on treatment with metal precursors, MCl₂ (M = Pd, Cu or Co) in toluene under reflux conditions afford mono- or dinuclear complexes [(L¹-H)₂M] (M= Pd (1) and Cu (2)) or [L²(μ-Cl)M]₂ (M= Cu (3) and Co (4)). The ligands and complexes were structurally characterized through single crystal X-ray diffraction and depending upon the type of compound, further characterized by spectroscopic (IR, Mass, NMR, EPR, UV-Vis), mircroanalytical (CHN), thermal (TGA) and electrochemical (CV) techniques. Complex 1 was employed in Suzuki-Miyaura coupling whereas complexes 2-4 were studied for the oxidation of secondary alcohols. These were found to be efficient catalysts for the respective reaction systems.