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Ruthenium tris(bipyridine) chloride

Systematic name Ruthenium tris(2,2’-bipyridine)-
dichloride hexahydrate
Other names Ru-bipy
Ruthenium-tris(2,2’-bipyridyl) dichloride
Tris(bipyridine)ruthenium(II) chloride
Molecular formula C30H24N6Cl2Ru.6H2O
Molar mass 748.62 g/mol
Appearance red-orange solid
CAS number [50525-27-4]
Density and phase solid
Solubility in water Soluble
Other solvents Alcohols
Melting point >300 °C
Molecular shape Octahedral
Dipole moment 0 D
Main hazards mildly toxic
R/S statement R: none
S: 22-24/25
RTECS number VM2730000
Supplementary data page
Spectral data UV λmax = 428 nm (ε = 11,700),
454 nm (ε = 14,000)
Related compounds
Related compounds Ruthenium trichloride
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Ruthenium(II) tris(bipyridine) dichloride is the chemical compound with the formula [Ru(bipy)3]Cl2. This salt is obtained as the hexahydrate, although all of the properties of interest are in the cation [Ru(bipy)3]2+, which has received much attention because of its distinctive optical properties. The chlorides can be replaced with other anions, such as PF6.


Synthesis and structure

This orange crystalline salt is prepared by treating aqueous solution of ruthenium trichloride with 2,2'-bipyridine. In this conversion, Ru(III) is reduced to Ru(II), and hypophosphorous acid is typically added as a reducing agent.[1]. [Ru(bipy)3]2+ is an octahedral coordination complex. The complex is chiral, with D3 symmetry. It has been resolved into its enantiomers, which are kinetically stable.

Photochemistry of [Ru(bipy)3]2+

Distinctively, [Ru(bipy)3]2+ absorbs UV light and visible light to give an excited state with a comparatively long lifetime of 600 nanoseconds. The excited state relaxes to the ground state by emission of a photon at the wavelength of 600 nm. The long lifetime of the excited state is attributed to the fact that it is triplet, whereas the ground state is a singlet state and in part due to the fact that the structure of the molecule allows for charge separation. Singlet-triplet transitions are often slow.

The triplet excited state has both oxidizing and reducing properties. This unusual situation arises because the excited state can be described as an Ru3+ complex containing a bipy- ligand. Thus, the photochemical properties of [Ru(bipy)3]2+ are reminiscent of the photosynthetic assembly, which also involves separation of an electron and a hole.[2]

[Ru(bipy)3]2+ has been examined as a photosensitiser for both the oxidation and reduction of water. Upon absorbing a photon, [Ru(bipy)3]2+ converts to the aforementioned triplet state, denoted [Ru(bipy)3]2+*. This species transfers an electron, located on one bipy ligand, to a sacrificial oxidant such as [persulfate|S2O8]2-. The resulting [Ru(bipy)3]3+ is a powerful oxidant and oxidizes water into O2 and protons via a metal oxide catalyst.[3] Alternatively, the reducing power of [Ru(bipy)3]2+* can harnessed to reduce methylviologen, a recyclable carrier of electrons, which in turn reduces protons at a platinum catalyst. For this process to be catalytic, a sacrificial reductant, such as EDTA4- or triethanolamine is provided to return the Ru(III) back to Ru(II).


The family of derivatives of [Ru(bipy)3]2+ is enormous. These complexes are widely used in biodiagnostics, photovoltaics and organic light-emitting diode.


Metal bipyridine as well as related phenanthroline complexes are generally bioactive.


  1. ^ Broomhead, J. A.; Young, C. G. “Tris(2,2’-bipyridine)Ruthenium(II) Dichloride Hexahydrate” Inorganic Syntheses, 1990, volume 28, ISBN 0-471-52619-3
  2. ^ A. J. Bard and M. A. Fox (1995). "Artificial Photosynthesis: Solar Splitting of Water to Hydrogen and Oxygen". Acc. Chem. Res. 28 (3): 141-145. doi:10.1021/ar00051a007.
  3. ^ M. Hara, C. C. Waraksa, J. T. Lean, B. A. Lewis and T. E. Mallouk (2000). "Photocatalytic Water Oxidation in a Buffered Tris(2,2'-bipyridyl)ruthenium Complex-Colloidal IrO2 System". J. Phys. Chem. A 104 (22): 5275-5280. doi:10.1021/jp000321x.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ruthenium_tris(bipyridine)_chloride". A list of authors is available in Wikipedia.
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