Heterobimetallic Cu(I)/Fe(II) azomethine bridged coordination-organometallic hybrid complexes: Synthesis, luminescence, electrochemical and catalytic properties

A new series of heterobimetallic complexes of the type [Cu(L)(PPh₃)₂]X (1–4) [where L = trans-4-(ferrocenylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one; PPh₃ = triphenylphosphine, X = NO₃⁻(1), ClO₄⁻ (2), BF₄⁻ (3) , PF₆⁻ (4)] were prepared by reaction of L with [Cu(MeCN)₂(PPh₃)₂]X and characterized by elemental analysis, FTIR, ¹H NMR, ³¹P NMR and UV–visible spectral studies. The thermal stability of (1–4) has been investigated by using thermogravimetric analysis (TGA). X-ray powder diffraction of the representative complex 1 used to clarify the crystal structure of the complex. The electrochemical behaviour of complexes (1–4) displayed quasireversible redox behaviour corresponding to Cu(I)/Cu(II) and Fe(II)/Fe(III) couples. All complexes show red emission as a result of ligand-ligand charge transfer (LLCT) and metal-ligand charge transfer (MLCT) or admixture of them. The catalytic efficiency of the complexes (1–4) was tested and it was found that the complex 4 worked as an effective catalyst for the C-N coupling reaction of aromatic amines and aryl halides.