Bis(cyclooctadiene)nickel(0)
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 455099150
| Name = Bis(cyclooctadiene)nickel(0)
| ImageFile = Ni(cod)2.svg
| ImageSize =
| IUPACName =
| OtherNames = nickel biscod, Ni(COD)2
|Section1={{Chembox Identifiers
| SMILES = C1CC=CCCC=C1.C1CC=CCCC=C1.[Ni]
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 17215769
| InChI = 1/2C8H8.Ni/c2*1-2-4-6-8-7-5-3-1;/h2*1-2,7-8H2;
| InChIKey = AYHVBQBQROAZHP-UHFFFAOYAH
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2C8H8.Ni/c2*1-2-4-6-8-7-5-3-1;/h2*1-2,7-8H2;
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = AYHVBQBQROAZHP-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 1295-35-8
| PubChem = 6433264
| RTECS = QR6135000
| EC_number = 215-072-0
| UNNumber = 1325
}}
|Section2={{Chembox Properties
| Formula = C16H24Ni
| MolarMass = 275.06 g/mol
| Appearance = Yellow solid
| Density =
| SolubleOther = soluble in benzene, tetrahydrofuran, toluene, diethyl ether, dimethylformamide
| MeltingPtC = 60
| MeltingPt_notes = (N2, decomposes)
| BoilingPt =
| Viscosity =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| NFPA-H =
| NFPA-R =
| NFPA-F =
| GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|228|317|334|350|351}}
| PPhrases = {{P-phrases|201|202|210|240|241|261|272|280|281|285|302+352|304+341|308+313|321|333+313|342+311|363|370+378|405|501}}
| FlashPt =
| AutoignitionPt =
}}
|Section8={{Chembox Related
| OtherFunction_label =
| OtherFunction =
}}
}}
Bis(cyclooctadiene)nickel(0) is the organonickel compound with the formula Ni(C8H12)2, also written Ni(cod)2. It is a diamagnetic coordination complex featuring tetrahedral nickel(0) bound to the alkene groups in two 1,5-cyclooctadiene ligands. This highly air-sensitive yellow solid is a common source of Ni(0) in chemical synthesis.{{cite journal | author-link = Günther Wilke | author = Wilke, G. | title = Contributions to Organo-Nickel Chemistry | journal = Angewandte Chemie International Edition | year = 1988 | volume = 27 | issue = 1 | pages = 185–206 | doi = 10.1002/anie.198801851 }}
Preparation and properties
The complex is prepared by reduction of anhydrous nickel(II) acetylacetonate in the presence of the diolefin:
:Ni(acac)2 + 2 cod + 2 AlEt3 → Ni(cod)2 + 2 acacAlEt2 + C2H6 + C2H4
Ni(cod)2 is moderately soluble in several organic solvents.{{Cite book| author1 = Schunn, R. A. | author-link2 = Steven Ittel | author2 = Ittel, S. D. | author3 = Cushing, M. A. | chapter = Bis(1,5-Cyclooctadiene)Nickel(0) | title = Inorganic Syntheses | series = Inorganic Syntheses | year = 1990 | volume = 28 | pages = 94–98 | doi = 10.1002/9780470132593.ch25 | isbn = 978-0-470-13259-3}}{{cite journal |last1=Wender |first1=Paul A. |last2=Smith |first2=Thomas E. |last3=Duong |first3=Hung A. |last4=Louie |first4=Janis |last5=Standley |first5=Eric A. |last6=Tasker |first6=Sarah Z. |title=Bis(1,5-cyclooctadiene)nickel(0) |journal=Encyclopedia of Reagents for Organic Synthesis |date=2015 |pages=1–15 |doi=10.1002/047084289x.rb118.pub3 |publisher=John Wiley & Sons Ltd |isbn=9780470842898 |language=en}}
If exposed to air, the solid oxidizes in a few minutes to nickel(II) oxide.{{cite journal|last1=Zhu|first1=Kake|last2=D'Souza|first2=Lawrence|last3=Richards|first3=Ryan M.|date=September 2005|title=Planting of bis(1,5-cyclooctadiene) nickel upon silica to harvest NiO (<5 nm) nanoparticles in a silica matrix|journal=Applied Organometallic Chemistry|volume=19|issue=9|pages=1065–1069|doi=10.1002/aoc.974}} As a result, this compound is generally handled in a glovebox.{{cite journal|last1=Tasker|first1=Sarah Z.|last2=Standley|first2=Eric A.|last3=Jamison|first3=Timothy F.|date=2014|title=Recent advances in homogeneous nickel catalysis|journal=Nature|volume=509|issue=7500|pages=299–309|doi=10.1038/nature13274|pmc=4344729|pmid=24828188|bibcode=2014Natur.509..299T }}
Reactions
The reactivity of Ni(cod)2 has been extensively examined. One or both 1,5-cyclooctadiene ligands are readily displaced by phosphines, phosphites, bipyridine, and isocyanides. {{cite web |title=Ni(COD)2 60+ Years – Still an Effective Source of Ni(0) in Organometallic Chemistry |url=https://www.strem.com/catalog/product_blog/328/5/ni_cod_2_60_years-still_an_effective_source_of_ni_0_in_organometallic_chemistry |website=Strem Chemical}}
Oxidation gives the highly reactive monocation, which can be isolated when using weakly coordinating anions:{{cite journal |doi=10.1002/anie.201506475 |title=[Ni(cod)2][Al(ORF)4], a Source for Naked Nickel(I) Chemistry |date=2015 |last1=Schwab |first1=Miriam M. |last2=Himmel |first2=Daniel |last3=Kacprzak |first3=Sylwia |last4=Kratzert |first4=Daniel |last5=Radtke |first5=Valentin |last6=Weis |first6=Philippe |last7=Ray |first7=Kallol |last8=Scheidt |first8=Ernst-Wilhelm |last9=Scherer |first9=Wolfgang |last10=De Bruin |first10=Bas |last11=Weber |first11=Stefan |last12=Krossing |first12=Ingo |journal=Angewandte Chemie International Edition |volume=54 |issue=49 |pages=14706–14709 |pmid=26458726 |pmc=5531756 }}
:{{chem2|Ni(cod)2 + Ag[Al(OCH(CF3)2)4] -> [Ni(cod)2][Al(OCH(CF3)2)4] + Ag}}
Of its many catalytic reactions, Ni(cod)2 in the presence of phosphine ligands catalyzes the demethoxylation of anisoles by hydrosilanes:{{cite journal|first1=Josep|last1 =Cornella|first2=Cayetana|last2=Zarate|first3=Ruben|last3=Martin |doi=10.15227/orgsyn.091.0260 |title=Ni-catalyzed Reductive Cleavage of Methyl 3-Methoxy-2-Naphthoate |date=2014 |journal=Organic Syntheses |volume=91 |pages=260–272 }}
:{{chem2|2 C6H5OCH3 + [(CH3)2HSi]2O -> 2 C6H6 + [(CH3)2(CH3O)Si]2O}}