Pd(II) complexes based on quinoline derivative: structural characterization and their role as a catalyst for hydrogenation of (E)-1-methyl-4-(2-nitrovinyl)benzene

Abstract

A series of two new Pd(II) complexes with ligand, HL, (z)-2-((quinolin-3-ylimino)methyl)phenol, derived from 3-aminoquinoline and 2-hydroxybenzaldehyde was reported. The structure of ligand, HL was determined by single crystal X-ray diffraction. The ligand, HL crystallizes in the space group P21/n of the monoclinic system with unit cell dimensions a=8.8733(8), b=6.3318(5), c=11.5145(9). The reaction of ligand, HL with PdX2 [X=Cl(-), OAc] in 2:1molar ratio yielded complexes of the type [Pd(HL)2X2] [X=Cl(-), OAc]. The ligand, HL and its Pd(II) complexes were characterized by various physico-chemical techniques; elemental analyses, ionization mass spectrometry (ESI-MS), UV/Vis, FT-IR, (1)H and (13)C NMR spectroscopy. UV/Vis absorption studies showed a square planar geometry around Pd (II) ion. The selective hydrogenation of (E)-1-methyl-4-(2-nitrovinyl)benzene in ethanol using synthesized Pd(II) complexes as catalysts was investigated at room temperature. The Pd(II) complexes catalyzed the hydrogenation of (E)-1-methyl-4-(2-nitrovinyl)benzene to (E)-1-methyl-4-(2-aminovinyl) benzene. Furthermore, the catalytic activity increased with increasing the quantity of Pd(II) complexes as catalysts.

Keywords: (z)-2-((Quinolin-3-ylimino)methyl)phenol; Crystal structure; Hydrogenation; Pd(II) complexes.