Polymorphism and thermodynamic properties of chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium(II) complex

• New polymorph of known ruthenium(II) complex has been synthesised.
• The real melting point of the obtained complex has been determined.
• An oxygen promoted oxidative dissociation of phosphine ligand was observed.

A new crystalline polymorph of known chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium(II) complex [RuCl(PPh3)2(η5-C5H5)] was obtained and characterized by various analytical methods including single-crystal and powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC) in combination with thermo-gravimetric analysis (TG-DSC). The obtained crystals of new polymorph are monoclinic, space group P21/n, with a = 11.125(4), b = 19.184(6), c = 15.946(5) Å, α = 90, β = 100.174(5), γ = 90, and Z = 4. It has been found that real melting point of the complex (M.p. = 252–253 °C) can be determined only in inert atmosphere while an apparent melting is observed in the range 142–150 °C due oxygen promoted oxidative dissociation of triphenylphosphine ligand.

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