2,2',6',2''-Terpyridine

Technical Specifications

Product Description & Scientific Applications

2,2':6',2''-Terpyridine, also sold as tripyridine, and its derivatives are the most used planar, tridentate ligand class in coordination chemistry.

Its three chelating pyridine rings raise the ligand-to-metal binding constant relative to bidentate analogues and give octahedral 2:1 complexes with no enantiomers, unlike those formed with bipyridine or phenanthroline. It is an unusually strong electron acceptor among N-donors, and is oxidatively and thermally robust. The ligand is redox non-innocent: in nickel alkyl–alkyl coupling the reduction of the alkyl halide is a ligand-based process.

Applications and Reactions

• Nickel-catalysed Negishi coupling: with NiCl₂·glyme in DMA, secondary propargylic bromides couple to secondary alkylzinc reagents at room temperature in 89% yield. Esters, ethers, carbamates and olefins are tolerated, the last without E/Z isomerisation.
• Cobalt hydroboration: a cobalt-alkyl NNN pincer complex of terpyridine hydroborates styrene with pinacolborane at 1 mol%, favouring Markovnikov regiochemistry.
• Iron hydrosilylation: iron(II) terpyridine complexes, after in situ reduction, catalyse hydrosilylation of terminal alkenes with primary and secondary silanes, giving linear products without competitive dehydrosilylation.
• Dye-sensitised solar cells: ruthenium(II) tris-thiocyanate complexes bearing a chelating terpyridine ligand act as panchromatic sensitisers, one reaching 10.3% solar conversion efficiency.
• Water oxidation: mononuclear [Mn(terpy)₂]²⁺ and dinuclear terpyridine-manganese complexes have been investigated electrochemically in aqueous solution.
• Ligand screening: in nickel-catalysed esterification with (−)-menthol, terpyridine gave 24% yield where bipyridine and phenanthroline gave none.

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