Spectroscopic and physico-chemical characterization of Ir(I) and Ru(III) complexes of 32-membered unsymmetrical dinucleating macrocyclic ligand

Abstract

Reactions of the macrocyclic ligand [L·2HClO4] with the reactants [Ir(CO)(Ph3P)2Cl] and [RuCl3(AsPh3)2CH3OH], produces bimetallic complexes with the stoichiometries [Ir2L(Ph3P)2Cl(ClO4)] (I) and [Ru2LCl4(ClO4)2] (II), respectively. Physico-chemical and spectroscopic data of the complexes confirms the encapsulation of two metal ions in the macrocyclic cavities via coordination through nitrogen atoms of the unsymmetrical aza groups, which results in homo-dinuclear macrocyclic complexes. The macrocyclic ligand has accommodated both the lower, Ir(I), and higher, Ru(III), oxidation states of metal ions, which shows the flexible nature and capability of macrocycle to form stable complexes. The mode of bonding and geometry of the complexes have been established on the basis of FT-IR, NMR, ligand field spectral, magnetic susceptibility and conductivity measurements. The thermodynamic first ionic association constants (K1), corresponding free energy change (ΔG) and other related parameters from conductometric studies using the Fuoss and Edelson method of complexes in DMSO have been determined and discussed.