(2,2′-Bipyridine)nickel(II) Dibromide | CAS 46389-47-3 | ≥97%

(2,2'-Bipyridine)nickel(II) dibromide ([Ni(bpy)Br₂], dibromo(2,2'-bipyridine)nickel(II), NiBr₂(bpy)) is a nickel(II) coordination complex in which 2,2'-bipyridine chelates the Ni(II) centre alongside two bromide ligands. Commercial material is supplied as a light yellow to amber to dark green powder or crystals. As a pre-assembled Ni/bipyridine complex, it provides a convenient entry point to catalyst systems based on the Ni(bpy) fragment — a motif widely used in modern nickel cross-coupling, radical, photoredox, and electroreductive chemistry. Ni/bipyridine systems access Ni(0), Ni(I), Ni(II), and Ni(III) manifolds, including open-shell Ni(I)/Ni(III) intermediates involved in radical and photoredox pathways.

Pre-assembled precatalyst

Supplied as a single, pre-formed Ni/bipyridine complex, it offers a convenient, easily weighed alternative to combining a separate nickel salt and bipyridine ligand in situ, or to handling highly air-sensitive Ni(0) sources such as Ni(cod)₂. In use, it is reduced in situ to the active low-valent nickel species by metallic reductants, photoredox cycles, or applied electrochemical potential.

Reductive cross-electrophile coupling

Ni/bipyridine catalyst systems are central to reductive cross-electrophile coupling, where aryl, heteroaryl, or vinyl halides are joined with alkyl electrophiles under stoichiometric reduction, commonly using zinc or manganese. Many of these reactions involve radical generation and capture by nickel, accessing Ni(I)/Ni(III) manifolds and enabling C(sp²)–C(sp³) bond formation — and, in selected cases, C(sp³)–C(sp³) coupling — directly from abundant electrophiles.

Suzuki–Miyaura cross-coupling

Ni/bipyridine and related pyridyl-ligated nickel systems support Suzuki–Miyaura chemistry beyond classical aryl–aryl coupling, including C(sp²)–C(sp³) bond formation from selected alkyl electrophiles such as sulfonates and alcohol-derived substrates.

Decarboxylative and single-electron transmetalation couplings

Ni/bipyridine systems participate in radical cross-couplings from redox-active carboxylic acid derivatives and from single-electron transmetalation precursors such as alkylsilicates, alkyltrifluoroborates, and related organoboron reagents, enabling C(sp²)–C(sp³) fragment coupling with aryl halides.

Metallaphotoredox dual catalysis

Paired with iridium or ruthenium polypyridyl photocatalysts, Ni/bipyridine complexes are among the most common nickel partners in metallaphotoredox dual catalysis. These systems combine nickel oxidative addition to aryl halides with photoredox generation of radical or nucleophilic coupling partners, enabling C–C and C–heteroatom bond formation under visible light. Certain Ni–bipyridine intermediates also participate in direct-excitation photochemistry, complementing systems that rely on a separate photosensitiser. These methods are widely used for late-stage functionalisation and fragment coupling in research synthesis.

C–N amination

Ni/bipyridine systems mediate C–N cross-coupling of aryl chlorides and bromides with primary and secondary amines under photochemical conditions, including direct excitation of nickel–bipyridine complexes, where photoinduced electron transfer assists otherwise challenging reductive elimination steps.

Electroreductive coupling

Ni/bipyridine systems are used in electroreductive coupling, where cathodic reduction can replace stoichiometric metal reductants in selected cross-electrophile and decarboxylative coupling reactions.

Beyond synthesis

• Artificial photosynthesis and CO₂-reduction models: nickel polypyridyl complexes, including Ni–bipyridine families, are studied as earth-abundant molecular catalysts for photocatalytic and electrocatalytic CO₂ reduction to CO, often paired with Ru(bpy)₃²⁺ photosensitisers or semiconductor light absorbers.
• Photophysics and mechanistic models: Ni–bipyridine halide and organonickel intermediates are studied by transient spectroscopy and direct-excitation experiments to understand charge transfer, radical generation, and metal–halide or metal–carbon bond homolysis in nickel photochemistry.