Terpyridine
| Terpyridine | |
|---|---|
| File:Terpyridine.svg | |
| 2,6-bis(2-pyridyl)pyridine | |
| Other names tripyridyl | |
| style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers | |
| CAS number | 1148-79-4 
|
| PubChem | 70848 |
| ChemSpider | 64012 |
| SMILES | Script error: No such module "collapsible list". |
| InChI | Script error: No such module "collapsible list". |
| style="background: #F8EABA; text-align: center;" colspan="2" | Properties | |
| Molecular formula | C15H11N3 |
| Molar mass | 233.27 g mol−1 |
| Appearance | colourless solid |
| Melting point |
88 °C |
| Boiling point |
370 °C[1] |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
Terpyridine (2,2';6',2"-terpyridine) is a heterocyclic compound derived from pyridine. This colourless solid is used as a ligand in coordination chemistry.
Synthesis
Terpyridine was first synthesized by G. Morgan and F. H. Burstall in 1932 by the oxidative coupling of pyridines. This method, however, proceeded in low yields. In 1991, a more efficient synthesis was described that involves the condensation of 2-acetylpyridine and enaminone, which is prepared by the reaction of 2-acetylpyridine with N,N-dimethylformamide dimethyl acetal. Alternatively, the base-catalyzed reaction of 2-acetylpyridine with carbon disulfide followed by alkylation with methyl iodide gives C5H4NCOCH=C(SMe)2. Condensation of this species with 2-acetylpyridine forms the related 1,5-diketone, which condenses with ammonium acetate to form a terpyridine. Treatment of this derivative with Raney nickel remove the thioether group.[2]
Other methods have been developed for the synthesis of terpy and its substituted derivatives. Substituted terpyridines are also synthesized from palladium-catalyzed cross-coupling reactions. It can be prepared from bis-triazinyl pyridine.
Properties
Terpyridine is a tridentate ligand that binds metals at three meridional sites giving two adjacent 5-membered MN2C2 chelate rings.[3] Terpy forms complexes with most transition metal ion as do other polypyridine compounds, such as 2,2'-bipyridine and 1,10-phenanthroline. Complexes containing two terpyridine complexes, i.e. [M(terpy)2]n+ are common. They differ structurally from the related [M(bipy)3]n+ complexes in being achiral.
Terpyridine complexes, like other polypyridine complexes, exhibit characteristic optical and electrochemical properties: metal-to-ligand charge transfer (MLCT) in the visible region, reversible reduction and oxidation, and fairly intense luminescence.
Because they are pi-acceptors, terpy and bipyridine too stabilize metals in lower oxidation states. For instance in acetonitrile solution, it is possible to generate the [M(terpy)2]+ (M = Ni, Co).
Related compounds
The bis-triazinyl pyridines are topologically related to terpy in their binding to metals.
See also
References
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<references />, or <references group="..." />- ↑ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 3–510, ISBN 0849305942
- ↑ Potts, K. T.; Ralli, P.; Theodoridis, G.; Winslow, P. (1990), "2,2':6',2' -Terpyridine", Org. Synth.; Coll. Vol., 7: 476 Missing or empty
|title=(help) - ↑ Anna L. Gavrilova, Brice Bosnich "Principles of Mononucleating and Binucleating Ligand Design" Chem. Rev. 2004, 104, 349-383. doi:10.1021/cr020604g
