Synthesis, spectral characterization, electrochemical studies and catalytic properties in Suzuki-Miyaura coupling reactions of the mononuclear Pd ^II, trinuclear Pd^II(BPh₂)₂ and Ru^II-Pd^II-Ru^II type complexes containing 4-amino-1-benzyl piperidine and phenyl groups

The ligand containing the 4-amino-1-benzyl piperidine group, N,N'-(4-amino-1-benzyl piperidine)-glyoxime, (LH₂) (1) was prepared from 4-amino-1-benzyl piperidine with anti-dichloroglyoxime at -15°C in absolute Tetrahydrofuran (THF). In the trinuclear [Pd(L)₂Ru ₂(phen)₄](ClO₄)₂ (4) and [Pd(L) ₂Ru₂(bpy)₄](ClO₄)₂ (5) metal complexes, the Pd^II ion centered into the main oxime core by the coordination of the imino groups while the two Ru^II ions coordinated dianionic oxygen donors of the oxime groups and linked to the ligands of 1,10-phenanthroline and 2,2'-bipyridine. The mono and trinuclear metal complexes were characterized by elemental analyses, FT-IR, UV-vis, ¹H and ¹³C-NMR spectra, magnetic susceptibility measurements, molar conductivity, cyclic voltammetry, mass spectra. X-ray powder techniques and their morphology by SEM measurements. The cyclic voltammetric results show that the cathodic peak (E_pc) potential of (3) shifts towards more positive values compared with that of (2) as a result of the BPh₂⁺-bridged complex formation. The Suzuki-Miyaura reaction was used to investigate their activity as catalyst either prepared in-situ or from well-defined complexes.