Chlorobis(cyclooctene)rhodium dimer
{{Chembox
|ImageFile = Rh2Cl2(coe)4corrected.png
|Section1={{Chembox Identifiers
|CASNo = 12279-09-3
|PubChem = 53384308
|ChemSpiderID = 21613963
|InChI=1S/4C8H14.2ClH.2Rh/c4*1-2-4-6-8-7-5-3-1;;;;/h4*1-2H,3-8H2;2*1H;;/p-2/b4*2-1-;;;;
|InChIKey = ZFCBAJWXKUDJSW-XFCUKONHSA-L
|SMILES = C1CCCC=CCC1.C1CCCC=CCC1.C1CCCC=CCC1.C1CCCC=CCC1.[Cl-].[Cl-].[Rh].[Rh] }}
|Section2={{Chembox Properties
|Formula = C32H56Cl2Rh2
|MolarMass = 717.50
|Appearance = red-brown solid
}}
|Section3={{Chembox Hazards
|GHSPictograms = {{GHS07}}
|GHSSignalWord = Warning
|HPhrases = {{H-phrases|302|312|315|319|332|335}}
|PPhrases = {{P-phrases|261|264|270|271|280|301+312|302+352|304+312|304+340|305+351+338|312|321|322|330|332+313|337+313|362|363|403+233|405|501}}
}}
}}
Chlorobis(cyclooctene)rhodium dimer is an organorhodium compound with the formula Rh2Cl2(C8H14)4, where C8H14 is cis-cyclooctene. Sometimes abbreviated Rh2Cl2(coe)4, it is a red-brown, air-sensitive solid that is a precursor to many other organorhodium compounds and catalysts.
The complex is prepared by treating an alcohol solution of hydrated rhodium trichloride with cyclooctene at room temperature.Van der Ent, A.; Onderdelinden, A. L. "Chlorobis(cyclooctene)rhodium(I) and di-μ-chlorobis[bis(cryclooctene)iridium] (I) complexes" Inorganic Syntheses 1973, volume 14, pp. 92-5. {{doi|10.1002/9780470132456.ch18}} The coe ligands are easily displaced by other more basic ligands, more so than the diene ligands in the related complex cyclooctadiene rhodium chloride dimer.
Catalyst for C-H activation
C-H activation is often catalyzed by chlorobis(cyclooctene)rhodium dimer as demonstrated in the synthesis of a strained bicyclic enamine.{{cite journal | last1 = Yotphan | first1 = Sirilata | last2 = Bergman | first2 = Robert G. | last3 = Ellman | first3 = Jonathan A. | title = The Stereoselective Formation of Bicyclic Enamines with Bridgehead Unsaturation via Tandem C–H Bond Activation/Alkenylation/ Electrocyclization | journal = J. Am. Chem. Soc. | date = 2008 | volume = 130 | issue = 8| pages = 2452–2453 | doi = 10.1021/ja710981b | pmid = 18247623 | pmc = 3062933 }}
:Image:BergMannCHActivation2008.svg
The synthesis of a mescaline analogue involves enantioselective annulation of an aryl imine via a C-H activation.{{Cite journal|title = Synthesis of a Tricyclic Mescaline Analogue by Catalytic C−H Bond Activation|journal = Organic Letters|date = 2003-04-01|issn = 1523-7060|pages = 1301–1303|volume = 5|issue = 8|doi = 10.1021/ol034228d|first1 = Kateri A.|last1 = Ahrendt|first2 = Robert G.|last2 = Bergman|first3 = Jonathan A.|last3 = Ellman|pmid=12688744}}
The total synthesis of lithospermic acid employs "guided C-H functionalization" late stage to a highly functionalized system. The directing group, a chiral nonracemic imine, is capable of performing an intramolecular alkylation, which allows for the rhodium-catalyzed conversion of imine to the dihydrobenzofuran.{{cite journal | title = Total Synthesis of (+)-Lithospermic Acid by Asymmetric Intramolecular Alkylation via Catalytic C-H Bond Activation | journal = J. Am. Chem. Soc. | year = 2005 | volume = 127 | issue = 39 | pages = 13496–13497 | last1 = O'Malley | first1 = S. J. | last2 = Tan | first2 = K. L. | last3 = Watzke | first3 = A. | last4 = Bergman | first4 = R. G. | last5 = Ellman | first5 = J. A. | doi = 10.1021/ja052680h | pmid=16190703}}
