Editing Terpyridine

{{Chembox
| Watchedfields = changed
| verifiedrevid = 470602628
| ImageFile = Terpyridine.svg
| ImageSize =
| PIN = 1<sup>2</sup>,2<sup>2</sup>:2<sup>6</sup>,3<sup>2</sup>-Terpyridine
| OtherNames = 2,6-Bis(2-pyridyl)pyridine, Tripyridyl, {{nowrap|2,2{{prime}}:6{{prime}},2{{pprime}}-Terpyridine}}
|Section1={{Chembox Identifiers
| InChI = 1/C15H11N3/c1-3-10-16-12(6-1)14-8-5-9-15(18-14)13-7-2-4-11-17-13/h1-11H
| InChIKey = DRGAZIDRYFYHIJ-UHFFFAOYAP
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 89445
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI =1S/C15H11N3/c1-3-10-16-12(6-1)14-8-5-9-15(18-14)13-7-2-4-11-17-13/h1-11H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = DRGAZIDRYFYHIJ-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 1148-79-4
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = G5E357ISH5
| PubChem = 70848
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 64012
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 245199
| SMILES = c1ccnc(c1)c2cccc(n2)c3ccccn3
  }}
|Section2={{Chembox Properties
| C=15 | H=11 | N=3
| Appearance = white solid
| Density =
| MeltingPtC = 88
| BoilingPtC = 370
| BoilingPt_ref = <ref name="hand">{{Citation | last = Lide | first = D. R. | year = 1998 | title = Handbook of Chemistry and Physics | edition = 87 | location = Boca Raton, Florida | publisher = CRC Press | isbn = 0-8493-0594-2 | pages = 3–510 }}</ref>
| Solubility =
  }}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
 }}
}}
'''Terpyridine''' (2,2';6',2"-terpyridine, often abbreviated to '''Terpy''' or '''Tpy''') is a [[heterocyclic compound]] derived from [[pyridine]]. It is a white solid that is soluble in most organic solvents.  The compound is mainly 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.  More efficient syntheses have since been described, mainly starting from [[2-acetylpyridine]].<ref>{{cite journal | last1 = Hofmeier | first1 = H. | last2 = Schubert | first2 = U. S. | year = 2004 | title = Recent developments in the supramolecular chemistry of terpyridine-metal complexes | journal = Chem. Soc. Rev. | volume = 33 | issue = 6| pages = 373–99 | doi = 10.1039/B400653B | pmid = 15280970 }}</ref> One method produces an enaminone by the reaction of 2-acetylpyridine with [[N,N-dimethylformamide]] dimethyl [[acetal]].<ref>{{cite book | last1 = Jameson | first1 = Donald L. | last2 = Guise | first2 = Lisa E. | chapter = 2,2′:6′,2″-Terpyridine | year = 1998 | title = Inorganic Syntheses | volume = 32 | pages = 46–50 | doi = 10.1002/9780470132630.ch7 | isbn = 978-0-471-24921-4 }}</ref>  The base-catalyzed reaction of 2-acetylpyridine with [[carbon disulfide]] followed by alkylation with [[methyl iodide]] gives C<sub>5</sub>H<sub>4</sub>NCOCH=C(SMe)<sub>2</sub>.  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]] removes the [[thioether]] group.<ref>{{ OrgSynth | author = Potts, K. T.; Ralli, P.; Theodoridis, G.; Winslow, P. | title = 2,2':6',2' - Terpyridine | collvol = 7 | collvolpages = 476 | year = 1990 | prep = cv7p0476 }}</ref>

Other methods have been developed for the synthesis of terpyridine and its substituted derivatives.<ref>Kamata, K., Suzuki, A., Nakai, Y., Nakazawa, H., "Catalytic Hydrosilylation of Alkenes by Iron Complexes Containing Terpyridine Derivatives as Ancillary Ligands", Organometallics 2012, 31, 3825. {{doi|10.1021/om300279t}}</ref>  Substituted terpyridines are also synthesized from [[palladium]]-catalyzed cross-coupling reactions. It can be prepared from [[bis-triazinyl pyridine]].

==Properties==
[[Image:TerpyRuCl3.svg|thumb|left|166px|[[(Terpyridine)ruthenium trichloride]] is a representative complex of terpyridine.]]
Terpyridine is a tridentate [[ligand]] that binds metals at three meridional sites giving two adjacent 5-membered MN<sub>2</sub>C<sub>2</sub> chelate rings.<ref>{{ cite journal |author1=Gavrilova, A. L. |author2=Bosnich, B. | title = Principles of Mononucleating and Binucleating Ligand Design | journal = Chemical Reviews | year = 2004 | volume =104 | issue = 2 | pages = 349–383 | doi = 10.1021/cr020604g | pmid=14871128}}</ref> Terpyridine forms complexes with most [[transition metal]] [[ion]] as do other [[polypyridine complex|polypyridine compounds]], such as [[2,2'-bipyridine]] and [[1,10-phenanthroline]]. Complexes containing two terpyridine complexes, i.e. [M(Terpy)<sub>2</sub>]<sup>n+</sup> are common.  They differ structurally from the related [M(Bipy)<sub>3</sub>]<sup>n+</sup> complexes in being achiral.

Terpyridine complexes, like other polypyridine complexes, exhibit characteristic optical and electrochemical properties: metal-to-ligand [[Intervalence charge transfer|charge transfer]] (MLCT) in the visible region, reversible [[Redox|reduction]] and [[oxidation]], and fairly intense [[luminescence]].

Because they are pi-acceptors, terpyridine and [[bipyridine]] tend to stabilize metals in lower oxidation states. For instance in [[acetonitrile]] solution, it is possible to generate the [M(Terpy)<sub>2</sub>]<sup>+</sup> (M = Ni, Co).

==Related compounds==
* [[bis-triazinyl pyridines]] are related to terpyridine in their binding to metals.
* [[quaterpyridine]]

==See also==
* [[Chelating ligand]]
* [[Pincer ligand]]
* [[Terthiophene]]

==References==
{{reflist}}

[[Category:Chelating agents]]
[[Category:Pyridines]]
[[Category:Heterocyclic compounds with 3 rings]]