{{chembox |Watchedfields = changed |verifiedrevid = 477198878 |Name = 2,2′-Bipyridine |ImageFile = Centro-bipyHoroz.png |ImageClass = skin-invert-image |ImageSize = 150 |ImageAlt = Skeletal formula of 2,2′-bipyridine |ImageFile1 = 2,2′-bipyridine-from-xtal-view-2-3D-bs-17.png |ImageClass1 = bg-transparent |ImageSize1 = 180 |ImageAlt1 = Ball-and-stick model of the 2,2′-bipyridine molecule |ImageFile2 = 2,2′-bipyridine-from-xtal-view-2-3D-sf.png |ImageClass2 = bg-transparent |ImageSize2 = 180 |ImageAlt2 = Space-filling model of the 2,2′-bipyridine molecule |ImageFile3 = 2,2'-bipyridine sample.jpg |ImageSize3 = 150 |PIN = 2,2′-Bipyridine |OtherNames = Bipyridyl<br />Dipyridyl<br />Bipy<br />Bpy<br />Dipy |Section1={{Chembox Identifiers |InChI = 1/C10H8N2/c1-3-7-11-9(5-1)10-6-2-4-8-12-10/h1-8H |InChIKey = ROFVEXUMMXZLPA-UHFFFAOYAP |ChEMBL_Ref = {{ebicite|correct|EBI}} |ChEMBL = 39879 |StdInChI_Ref = {{stdinchicite|correct|chemspider}} |StdInChI = 1S/C10H8N2/c1-3-7-11-9(5-1)10-6-2-4-8-12-10/h1-8H |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |StdInChIKey = ROFVEXUMMXZLPA-UHFFFAOYSA-N |CASNo_Ref = {{cascite|correct|CAS}} |CASNo = 366-18-7 |UNII_Ref = {{fdacite|correct|FDA}} |UNII = 551W113ZEP |SMILES = n1ccccc1-c2ccccn2 |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |ChEBI_Ref = {{ebicite|correct|EBI}} |ChEBI = 30351 |ChemSpiderID = 13867714 |RTECS = DW1750000 |PubChem = 1474 |EC_number = 206-674-4 923-456-0 |Beilstein = 113089 |Gmelin = 3720 936807 }} |Section2={{Chembox Properties |Formula={{chem2|(C5H4N)2}} |MolarMass = 156.18 |Appearance = Colorless solid |MeltingPtC = 70 to 73 |BoilingPtC = 273 }} |Section3={{Chembox Structure |Dipole = 0 D }} |Section7={{Chembox Hazards |MainHazards = toxic |LD50 = 15-78 mg/kg (oral, rat); 20-140 mg/kg (oral, mouse) |GHSPictograms = {{GHS06}}{{GHS07}} |GHSSignalWord = Danger |HPhrases = {{H-phrases|301|302|311|312|319|412}} |PPhrases = {{P-phrases|264|270|273|280|301+310|301+312|302+352|305+351+338|312|321|322|330|337+313|361|363|405|501}} }} |Section8={{Chembox Related | OtherCompounds = 4,4′-Bipyridine<br/>Pyridine<br />Phenanthroline<br />3-Pyridylnicotinamide<br />Terpyridine<br />Biphenyl }} }}
'''2,2′-Bipyridine''' ('''bipy''' or '''bpy''', pronounced {{IPAc-en|ˈ|b|ɪ|p|iː}}){{citation needed|date=April 2025}} is an organic compound with the formula {{Chem2|(C5H4N)2|auto=yes}}. This colorless solid is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals. Ruthenium and platinum complexes of bipy exhibit intense luminescence.<ref>{{cite book |author1=Broomhead J. A. |author2=Young C. G. |chapter=Tris(2,2″-Bipyridine)Ruthenium(II) Dichloride Hexahydrate | year = 1990 | title = Inorganic Syntheses | volume = 28 | pages = 338–340 | doi = 10.1002/9780470132593.ch86 |isbn=978-0-470-13259-3 }}</ref> ==Preparation, structure, and general properties== 2,2'-Bipyridine was first prepared by decarboxylation of divalent metal derivatives of pyridine-2-carboxylate:<ref name=Constacraft>{{cite journal |doi=10.3390/molecules24213951|doi-access=free|title=The Early Years of 2,2'-Bipyridine—A Ligand in its Own Lifetime|year=2019|last1=Constable|last2=Housecroft|journal=Molecules|volume=24|issue=21|page=3951|pmid=31683694|pmc=6864536}}</ref>
{{chem2|2C5H4NCOO- -> (C5H4N)2 + 2CO2 + 2e-}}
It is prepared by the dehydrogenation of pyridine using Raney nickel:<ref>{{OrgSynth | author = Sasse, W. H. F. | title = 2,2′-Bipyridine | year = 1966 | volume = 46 | pages = 5 | doi = 10.15227/orgsyn.046.0005 }}</ref>
{{chem2|2C5H5N -> (C5H4N)2 + H2}}
===Substituted 2,2'-bipyridines=== Unsymmetrically substituted 2,2'-bipyridines can be prepared by cross coupling reaction of 2-pyridyl and substituted pyridyl reagents.<ref>{{cite journal |doi=10.15227/orgsyn.089.0076 |title=Discussion Addendum for: Synthesis of 4-, 5-, and 6-Methyl-2,2'-bipyridine by a Negishi Cross-Coupling Strategy: 5-Methyl-2,2'-bipyridine |journal=Organic Syntheses |date=2012 |volume=89 |page=76|first1=Tiandong|last1=Liu|first2=Cassandra L.|last2=Fraser }}</ref>
==Structure== Although bipyridine is often drawn with its nitrogen atoms in ''cis'' conformation, the lowest energy conformation both in solid state and in solution is in fact coplanar, with nitrogen atoms in ''trans'' position.<ref>{{cite journal |author1=Merritt, L. L. |author2=Schroeder, E. | title = The Crystal Structure of 2,2′-Bipyridine | journal = Acta Crystallographica | year = 1956 | volume = 9 | issue = 10 | pages = 801–804 | doi = 10.1107/S0365110X56002175| doi-access = free }}</ref> Monoprotonated bipyridine adopts a ''cis'' conformation.<ref>{{cite journal |author1=Göller, A. |author2=Grummt, U.-W. | title = Torsional barriers in biphenyl, 2,2′-bipyridine and 2-phenylpyridine | journal = Chemical Physics Letters | year = 2000 | volume = 321 | issue = 5–6 | pages = 399–405 | doi = 10.1016/S0009-2614(00)00352-3 |bibcode=2000CPL...321..399G}}</ref>
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==Reactions== 2,2'-bipyridine produces multiple coordination complexes. It binds metals as a ligand for chelation, forming a 5-membered chelate ring.
==See also== * 2,2'-Biquinoline * 1,10-Phenanthroline * Dimethyl-2,2'-bipyridine
==References== {{reflist}}
{{DEFAULTSORT:Bipyridine, 2,2'-}} Category:Chelating agents Category:Bipyridines Category:2-Pyridyl compounds Category:Symmetrical biaryls