Norbornadiene
{{chembox
|Watchedfields = changed
|verifiedrevid = 404998665
|ImageFile = norbornadiene.png
|ImageSize = 150px
|ImageFileL1 = Norbornadiene-from-xtal-3D-bs-17.png
|ImageFileR1 = Norbornadiene-from-xtal-3D-sf.png
|PIN = Bicyclo[2.2.1]hepta-2,5-diene
|OtherNames = 2,5-Norbornadiene
|Section1={{Chembox Identifiers
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 121-46-0
|ChemSpiderID = 8160
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = W9ZTQ75ZUS
|EINECS = 204-472-0
|PubChem = 8473
|UNNumber = 2251
|SMILES = C1C2C=CC1C=C2
|StdInChI=1S/C7H8/c1-2-7-4-3-6(1)5-7/h1-4,6-7H,5H2
|StdInChIKey = SJYNFBVQFBRSIB-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
|Formula = C7H8
|MolarMass = 92.14 g/mol
|Density = 0.906 g/cm3
|MeltingPtC = -19
|BoilingPtC = 89
|BoilingPt_notes =
|Solubility = Insoluble
}}
|Section7={{Chembox Hazards
|GHSPictograms = {{GHS02}}
|GHSSignalWord = Danger
|HPhrases = {{H-phrases|225}}
|PPhrases = {{P-phrases|210|233|240|241|242|243|280|303+361+353|370+378|403+235|501}}
}}
}}
Norbornadiene is an organic compound and a bicyclic hydrocarbon. Norbornadiene is of interest as a metal-binding ligand, whose complexes are useful for homogeneous catalysis. It has been intensively studied owing to its high reactivity and distinctive structural property of being a diene that cannot isomerize (isomers would be anti-Bredt alkenes). Norbornadiene is also a useful dienophile in Diels-Alder reactions.
Synthesis
Norbornadiene can be formed by a Diels-Alder reaction between cyclopentadiene and acetylene{{Cite journal |last=Orrego‐Hernández |first=Jessica |last2=Hölzel |first2=Helen |last3=Quant |first3=Maria |last4=Wang |first4=Zhihang |last5=Moth‐Poulsen |first5=Kasper |date=2021-10-14 |title=Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry |url=https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202100795 |journal=European Journal of Organic Chemistry |language=en |volume=2021 |issue=38 |pages=5337–5342 |doi=10.1002/ejoc.202100795 |issn=1434-193X}}
:Image:Norbornadiene synthesis.png
{{clear|left}}
Reactions
Quadricyclane, a valence isomer, can be obtained from norbornadiene by a photochemical reaction when assisted by a sensitizer such as acetophenone:{{OrgSynth | author = Smith, Claiborune D. | title = Quadricyclane | prep = cv6p0962 | collvol = 6 | collvolpages = 962 | year = 1988}}
The norbornadiene-quadricyclane couple is of potential interest for solar energy storage when controlled release of the strain energy stored in quadricyclane back to norbornadiene is made possible.{{cite journal | title = Rh(III)-Photosensitized Interconversion of Norbornadiene and Quadricyclane |author1=Gregory W. Sluggett |author2=Nicholas J. Turro |author3=Heinz D. Roth |name-list-style=amp | journal = J. Phys. Chem. A | year = 1997 | volume = 101 | pages = 8834–8838 | doi = 10.1021/jp972007h | issue = 47|bibcode=1997JPCA..101.8834S |citeseerx=10.1.1.130.1791}}
Norbornadiene is reactive in cycloaddition reactions. Norbornadiene is also the starting material for the synthesis of diamantaneDiamantane in Organic Syntheses Coll. Vol. 6, p.378; Vol. 53, p.30 [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv6p0378 Online Article] {{Webarchive|url=https://web.archive.org/web/20120728090855/http://www.orgsyn.org/orgsyn/prep.asp?prep=cv6p0378 |date=2012-07-28 }} and sumanene and it is used as an acetylene transfer agent for instance in reaction with 3,6-di-2-pyridyl-1,2,4,5-tetrazine.{{cite journal | title = π-Bond Screening in Benzonorbornadienes: The Role of 7-Substituents in Governing the Facial Selectivity for the Diels-Alder Reaction of Benzonorbornadienes with 3,6-Di(2-pyridyl)-s-Tetrazine |author1=Ronald N. Warrener |author2=Peter A. Harrison |name-list-style=amp | journal = Molecules | year = 2001 | volume = 6 | pages = 353–369 | url = http://www.mdpi.org/molecules/papers/60400353.pdf | pmc=6236418| doi = 10.3390/60400353 | issue = 4|s2cid=53874105 | doi-access = free}}
=As a ligand=
Norbornadiene is a versatile ligand in organometallic chemistry, where it serves as a two-electron or four-electron donor. (Norbornadiene)molybdenum tetracarbonyl is used as a source of "Mo(CO)4", exploiting the lability of the diene ligand in this case.{{cite journal | title = High yield synthesis and structures of some achiral and chiral (diphosphine)tetracarbonylchromium(0) chelate complexes with tetracarbonyl(norbornadiene)chromium(0) as complexation reagent |author1=Markus Strotmann |author2=Rudolf Wartchow |author3=Holger Butenschön |name-list-style=amp | journal = Arkivoc | pages = KK–1112F | year = 2004 | url = http://www.arkat-usa.org/ark/journal/2004/I13_Krohn/1112/KK-1112F.asp }} which is a useful source of "chromium tetracarbonyl," e.g. in reactions with phosphine ligands.
The norbornadiene analogue of cyclooctadiene rhodium chloride dimer has been used in homogeneous catalysis. Chiral, C2-symmetric dienes derived from norbornadiene have also been described.Ryo Shintani, Tamio Hayashi "Chiral Diene Ligands for Asymmetric Catalysis" Aldrich Chimica Acta 2009, vol. 42, number 2, pp. 31-38.{{cite journal |doi=10.1021/acs.chemrev.2c00218|title=Chiral Diene Ligands in Asymmetric Catalysis |year=2022 |last1=Huang |first1=Yinhua |last2=Hayashi |first2=Tamio |journal=Chemical Reviews |volume=122 |issue=18 |pages=14346–14404 |pmid=35972018 }}
See also
- Norbornane a saturated compound with the same carbon skeleton.
- Norbornene a compound with the same carbon skeleton, but with one less double bond.