Paramagnetic ruthenium (III) complex,[(C 5 Me 5) RuCl 2] n, is prepared by the reaction of RuCl 3· H 2 O with C 5 Me 5 H in refluxing ethanol. Treatment of [Cp* RuCl 2] n (Cp*= C 5 Me 5) with cyclic dienes or α, ω-bis (diphenylphosphino) alkanes gives diamagnetic Ru (II) complexes, Cp* RuCl (diene) or Cp* RuCl (dipos), respectively. Cationic diene complex of ruthenium is formed by the reaction of Cp* RuCl (2, 5-norbornadiene) with AgBF 4.