Abstract In a comparative study, half-sandwich complexes of Ru II (1) with pyridine-based chelating diamine [NN= 2-aminomethylpiperidine (ampi), a; 2-aminomethylpyridine (ampy), b; 8-aminoquaniline (aquan), c; 4, 4′-dimethyl-2, 2′-bipyridine (dbipy), d; 2, 2′-bipyridine (bipy), e] or amine amide (Ts-ampi, 2a) were synthesized by cleavage of [{(η 6-p-cymene) Ru (μ-Cl) Cl} 2] dimer and the resulting complexes were screened for their efficiency in the ...