In this research study, the formation and characterization
of new ruthenium(II) and (III) complexes encompassing
multidentate ligands derived from 6-acetyl-1,3,
7-trimethyllumazine (almz) are reported. The 1:1 molar coordination
reactions of trans-[RuCl2(PPh3)3] with N-1-[1,3,
7-trimethyllumazine]benzohydride (bzlmz) and 6-(N-methyloxime)-
1,3,7-trimethyllumazine (ohlmz) formed a diamagnetic
ruthenium(II) complex, cis-[RuCl2(bzlmz)(PPh3)] (1),
and paramagnetic complex, cis-[RuIIICl2(olmz)(PPh3)] (2)
[Holmz = 6-(N-hydroxy-N0-methylamino)-1,3,7-trimethyllumazine],
respectively. These ruthenium complexes were
characterized via physico-chemical and spectroscopic
methods. Structural elucidations of the metal complexes
were confirmed using single crystal X-ray analysis. The
redox properties of the metal complexes were investigated
via cyclic voltammetry. Electron spin resonance spectroscopy
confirmed the presence of a paramagnetic metal
centre in 2. The radical scavenging activities of the metal
complexes were explored towards the DPPH and NO radicals.
Quantum calculations at the density functional theory
level provided insight into the interpretation of the IR and
UV–Vis experimental spectra of 1
