Tris(2,2'-bipyridine)ruthenium(II) Dichloride

Technical Specifications

Product Description & Scientific Applications

[Ru(bpy)3]2+, the tris(2,2'-bipyridyl)ruthenium(II) cation, is the archetypal visible-light photoredox catalyst. Absorption in the MLCT band (ε452 ≈ 14,600 M−1cm−1) is followed by near-unity intersystem crossing to a long-lived 3MLCT state (λem ≈ 615 nm; typically ~0.6–0.9 µs in deoxygenated aqueous or organic media) that can act as both a photo-oxidant and a photo-reductant. Reductive quenching by a sacrificial donor generates the strongly reducing Ru(bpy)3+, while oxidative quenching generates the strongly oxidising Ru(bpy)33+; the ground-state couples are E(Ru3+/Ru2+) ≈ +1.29 V and E(Ru2+/Ru+) ≈ −1.33 V vs SCE. These two manifolds underpin the methodologies below.

Synthetic methodologies developed with this catalyst

• Tin-free reductive dehalogenation: reduction of activated C–X bonds using i-Pr2NEt with HCO2H or Hantzsch ester as hydrogen-atom donor, chemoselective over aryl and vinyl halides and operable on preparative scale.
• [2+2] cycloadditions: reductive radical-anion [2+2] cycloadditions of enones and oxidative radical-cation [2+2] cycloadditions of electron-rich olefins, including methyl-viologen-mediated variants, giving substituted cyclobutanes.
• Formal [3+2] cycloadditions: visible-light ring-opening coupling of aryl cyclopropyl ketones with alkenes, under Lewis-acid/base assistance, to give highly substituted cyclopentanes.
• Enantioselective α-alkylation of aldehydes: dual photoredox–organocatalysis with a chiral imidazolidinone and activated alkyl halides, giving enantioenriched α-alkyl aldehydes.
• C–H alkylation of electron-rich heteroarenes: direct functionalisation of indoles, pyrroles and furans with activated alkyl bromides such as diethyl bromomalonate.
• Oxidative cross-dehydrogenative coupling (CDC): aerobic α-C–H functionalisation of N-aryltetrahydroisoquinolines through photogenerated iminium ions, coupling with nucleophiles such as nitroalkanes (the aza-Henry/nitro-Mannich reaction).
• Addition to N-acyliminium ions: nucleophile addition to N-acylimines generated in situ from α-amidosulfides, giving α,α-disubstituted amines.
• Radical fluoroalkylation: azido- and aminotrifluoromethylation of alkenes with an electrophilic CF3 source such as Umemoto’s reagent, and radical addition to trifluoromethyl ketones to give trifluoromethyl carbinols.
• Energy-transfer catalysis: triplet-sensitised alkene E/Z isomerisation of accessible-triplet-energy substrates such as stilbenes, with no change in catalyst oxidation state.
• Photocontrolled radical polymerisation: visible-light RAFT (PET-RAFT), in which Ru(bpy)32+ operates through coupled electron- and/or energy-transfer pathways.

Beyond synthesis

• Electrochemiluminescence: the foundational coreactant ECL luminophore; electro-oxidation with tri-n-propylamine (TPrA) populates the 3MLCT state to emit near 615 nm without optical excitation (peroxydisulfate as cathodic coreactant), underpinning immunoassay, biosensor and analytical detection.
• Solar-fuel research: a classic photosensitiser in multicomponent hydrogen-evolution systems, paired with sacrificial donors, methyl-viologen relays and proton-reduction catalysts such as platinum colloids or cobaloximes.

Shipping Destinations

• EU & UK: Priority delivery, 2–5 business days.
• United States (DDP): 3–7 business days, duties and taxes prepaid.
• EFTA Countries (DDP): 3–7 business days, duties and taxes prepaid.
• Worldwide: 7–14 business days, selected locations.