One-pot synthesis of cis-bis(2,2′-bipyridine)carbonylruthenium(II) complexes from a carbonato precursor: X-ray crystal structures and electron transfer processes of the series complexes

Abstract

The reaction of Brønsted acids with cis-[Ru(bpy)₂(CO₃)] (bpy = 2,2′-bipyridine) under CO results in cleavage of the carbonato ligand and formation of cationic cis-[Ru(bpy)₂(CO)L] ^{n +} complexes [L = ONO₂ (1 ⁺), OH₂ (2 ²⁺), Cl (3 ⁺), OCOH (4 ⁺), and OCOCH₃ (5 ⁺)]. The structures of 1 ⁺ and 2 ²⁺ were confirmed by single-crystal X-ray diffraction. Crystal data for 1(PF₆): monoclinic, P2₁/c, a = 10.5242(3), b = 15.4727(3), c = 14.6571(3) Å, β = 92.3219(9)°, V = 2384.77(9) ų, Z = 4, D _calcd = 1.806 g cm⁻³, 5460 unique reflections (R _int = 0.032), R ₁ = 0.0540 [I > 2σ(I)], wR ₂ = 0.1642 (all reflections); crystal data for 2(ClO₄)₂ · H₂O: monoclinic, C2/c, a = 20.4247(7), b = 10.0777(3), c = 15.6039(5) Å, β = 127.7569(8)°, V = 2539.31(14) ų, Z = 4, D _calcd = 1.769 g cm⁻³, 2895 unique reflections (R _int = 0.036), R ₁ = 0.0343 [I > 2σ(I)], wR ₂ = 0.0907 (all reflections). Except for 2(PF₆)₂ the complexes exhibit oxidation at 1.02–1.30 V versus Fc⁺/Fc in acetonitrile. Bipyridine-centered reductions are also observed; these redox potentials depend on the nature of L. This convenient synthesis will be useful for producing cis-[Ru(bpy)₂(CO)L] ^{n +}-type complexes in high yield.

Keywords:

• Ruthenium
• Bipyridine complex
• Crystal structure
• One-pot synthesis
• Electron transfer

Acknowledgments

We thank Mr Hiroki Hoshi of Fukushima University for his technical assistance.