Hexadecacarbonylhexarhodium
{{chembox
| Watchedfields = changed
| verifiedrevid = 440642858
| ImageFile = Hexadecacarbonylhexarhodium.svg
| ImageSize = 200px
| IUPACName = Hexadecacarbonylhexarhodium
| OtherNames = Hexarhodium hexadecacarbonyl
| Section1= {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|ECHA}}
| CASNo = 28407-51-4
| EINECS = 249-009-3
| PubChem = 10866043
| ChemSpiderID = 9041327
| StdInChI=1S/16CO.6Rh/c16*1-2;;;;;;
| StdInChIKey = SZQABOJVTZVBHE-UHFFFAOYSA-N
| SMILES = [C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[Rh].[Rh].[Rh].[Rh].[Rh].[Rh]
}}
| Section2= {{Chembox Properties
| Formula= C16O16Rh6
| MolarMass = 1065.62 g/mol
| Appearance = purple-brown solid
| MeltingPtC = 235
}}
|Section7 = {{Chembox Hazards
| GHSPictograms = {{GHS07}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|312|332}}
| PPhrases = {{P-phrases|261|264|270|271|280|301+312|302+352|304+312|304+340|312|322|330|363|501}}
}}
}}
Hexadecacarbonylhexarhodium is a metal carbonyl cluster with the formula Rh6(CO)16. It exists as purple-brown crystals that are slightly soluble in dichloromethane and chloroform. It is the principal binary carbonyl of rhodium.
Discovery and synthesis
Rh6(CO)16 was first prepared by Walter Hieber in 1943 by carbonylation of RhCl3·3H2O at 80–230 °C and 200 atm carbon monoxide with silver or copper as a halide acceptor. Hieber correctly formulated the compound as a binary carbonyl, but suggested the formula Rh4(CO)11, i.e., CO/Rh ratio of 2.75.{{cite journal|doi=10.1002/zaac.19432510110|title=Über Metallcarbonyle. XLV. Das Rhodium im System der Metallcarbonyle|year=1943|last1=Hieber|first1=W.|last2=Lagally|first2=H.|journal=Zeitschrift für Anorganische und Allgemeine Chemie|volume=251|issue=1|pages=96–113}} The correct formula and structure was subsequently established by Dahl et al. using X-ray crystallography. The correct CO/Rh ratio is 2.66.{{cite journal | title = Rh6(CO)16 and its Identity with Previously Reported Rh4(CO)11 | first1 = Eugene R. | last1 = Corey | first2 = Lawrence F. | last2 = Dahl | authorlink2 = Lawrence F. Dahl | first3 = Wolfgang | last3 = Beck | journal = J. Am. Chem. Soc. | year = 1963 | volume = 85 | issue = 8 | pages = 1202–1203 | doi = 10.1021/ja00891a040| bibcode = 1963JAChS..85.1202C }}
Relative to the original preparation, the carbonylation of a mixture of anhydrous rhodium trichloride and iron pentacarbonyl was shown to give good yields of Rh6(CO)16.{{cite journal | doi = 10.1016/S0022-328X(00)87682-2 | title = Metal carbonyl chemistry IV. The preparation of cobalt and rhodium carbonyls by reductive carbonylation with pentacarbonyliron | year = 1968 | last1 = Booth | first1 = B. L. | last2 = Else | first2 = M. J. | last3 = Fields | first3 = R. | last4 = Goldwhite | first4 = H. | last5 = Haszeldine | first5 = R. N. | journal = J. Organomet. Chem. | volume = 14 | issue = 2 | pages = 417–422}} Other compounds of rhodium are also effective precursors such as [(CO)2Rh(μ-Cl)]2 and rhodium(II) acetate:{{cite book | first1 = B. R. | last1 = James | first2 = G. L. | last2 = Rempel | first3 = W. K. | last3 = Teo | title = Inorganic Syntheses | chapter = Hexadecacarbonylhexarhodium | journal = Inorg. Synth. | volume = 16 | year = 1976 | doi=10.1002/9780470132470.ch15 | page = 49| isbn = 978-0-470-13178-7 }}
:3 Rh2(O2CCH3)4 + 22 CO + 6 H2O → Rh6(CO)16 + 6 CO2 + 12 CH3COOH
:3 [(CO)2RhCl]2 + 4 CO + 6 Cu → Rh6(CO)16 + 6 CuCl
It also arises quantitatively by thermal decomposition of tetrarhodium dodecacarbonyl in boiling hexane:
:{{chem2|3 Rh4(CO)12 -> 2 Rh6(CO)16 + 4 CO}}
Reactions
At least some of the CO ligands can be displaced by donor ligands.{{cite book |doi=10.1002/9780470132623.ch37|title=Acetonitrile-Substituted Derivatives of Rh6(CO)16 : Rh6(CO)16-x(NCMe)x (x = 1,2) |series=Inorganic Syntheses |year=1977 |last1=Tunik |first1=S. P. |last2=Vlasov |first2=A. V. |last3=Krivykh |first3=V. V. | chapter=Acetonitrile-Substituted Derivatives of Rh 6 (CO) 16 : Rh 6 (CO) 16-X (NCMe) X ( X = 1,2) |pages=239–244|volume=31| isbn=978-0-471-15288-0 }}
Rh6(CO)16 catalyzes a number of organic reactions including hydrogenation and hydroformylation.
References
{{reflist}}
{{Rhodium compounds}}
Category:Organorhodium compounds