Cis-Dichlorobis(ethylenediamine)cobalt(III) chloride and Chloro(pyridine)cobaloxime: Difference between pages
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{{DISPLAYTITLE:''cis''-Dichlorobis(ethylenediamine)cobalt(III) chloride}} |
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| verifiedrevid = 402148878 |
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{{chembox |
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| Name = Chloro(pyridine)cobaloxime(III) |
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| verifiedrevid = 399718045 |
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| ImageFile1 = Structure of Chloro(pyridine)cobaloxime fixed.png |
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| Name=''cis''-Dichlorobis(ethylenediamine)cobalt(III) chloride |
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| ImageFile2 = Sample of Chloro(pyridine)cobaloxime(III).jpg |
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| ImageFile = Cis-Dichlorobis(ethylenediamine)cobalt(III) chloride.png |
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| OtherNames = Chloro(pyridine)bis(dimethylglyoximato)cobalt(III), Chloro(N,N'-dihydroxy-2,3-butanediimine-κ2N,N')(N-hydroxy-2,3-butanediiminato-κ2N,N')(methanol)cobalt - pyridine (1:1) |
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| Name = cis-dichlorobis(ethylenediamine)cobalt(III) chloride |
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|Section1={{Chembox Identifiers |
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| OtherNames = |
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| ChemSpiderID_Ref = |
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| Section1 = {{Chembox Identifiers |
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| ChemSpiderID = 28296302 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| EINECS = 625-485-1 |
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| ChemSpiderID = 360279 |
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| PubChem = |
| PubChem = 154824519 |
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| InChI = |
| InChI = 1S/C9H17N4O4.C5H5N.ClH.Co/c1-6(10)7(2)11-16-19-17-13-9(4)8(3)12-15-18-14-5;1-2-4-6-5-3-1;;/h1-5H3;1-5H;1H;/q-1;;; 2/p-1/b11-7 ,12-8 ,13-9 ;;; |
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| SMILES = CO[H]O\N1=C(/C)\C(\C)=N2\O[H]O\N3=C(/C)\C(\C)=N/[Co]123Cl.c1ccccn1 |
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| InChIKey = LBGRXLRZGLIOLI-NUQVWONBAE |
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| StdInChI_Ref = |
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| SMILES = Cl[Co]Cl.[NH-]CC[NH-].[NH-]CC[NH-] |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/2C2H6N2.2ClH.Co/c2*3-1-2-4;;;/h2*3-4H,1-2H2;2*1H;/q2*-2;;;+2/p-2 |
| StdInChI = 1S/2C2H6N2.2ClH.Co/c2*3-1-2-4;;;/h2*3-4H,1-2H2;2*1H;/q2*-2;;;+2/p-2 |
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| StdInChIKey_Ref = |
| StdInChIKey_Ref = |
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| StdInChIKey = |
| StdInChIKey = CZHYJYFFRNANOP-DSUIRYESSA-M |
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| CASNo_Ref = |
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| CASNo = 23295-32-1 |
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| RTECS = |
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}} |
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}} |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = C<sub>4</sub>H<sub>16</sub>Cl<sub>3</sub>CoN<sub>4</sub> |
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| Formula = C<sub>13</sub>H<sub>19</sub>ClCoN<sub>5</sub>O<sub>4</sub> |
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| Appearance = violet solid |
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| C=13 | H=19 | Cl=1 | Co=1 | N=5 | O=4 |
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| Density = |
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| Appearance = yellow-brown solid |
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| Solubility = good |
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| Density = |
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| MeltingPt = dec. |
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| Solubility = insoluble |
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| BoilingPt = |
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| MeltingPt = |
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| BoilingPt = |
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| Section3 = {{Chembox Structure |
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| Coordination = |
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|Section3={{Chembox Structure |
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| CrystalStruct = |
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| Coordination = |
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| CrystalStruct = |
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| Section7 = {{Chembox Hazards |
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| ExternalMSDS = |
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|Section7={{Chembox Hazards |
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| EUClass = |
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| ExternalSDS = |
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| RPhrases = {{R36/37/38}} |
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| |
| GHSPictograms = {{GHS07}} |
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| GHSSignalWord = Warning |
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| FlashPt = |
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| HPhrases = {{H-phrases|315|319|335}} |
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}} |
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| PPhrases = {{P-phrases|}} |
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| FlashPt = |
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'''Chloro(pyridine)cobaloxime''' is a [[coordination compound]] containing a Co<sup>III</sup> center with octahedral coordination. It has been considered as a model compound of [[cyanocobalamin|vitamin B<sub>12</sub>]] for studying the properties and mechanism of action of the vitamin. It belongs to a class of bis(dimethylglyoximato)cobalt(III) complexes with different axial ligands, called [[cobaloximes]].<ref name="SupraChem">{{cite book |
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'''''cis''-Dichlorobis(ethylenediamine)cobalt(III) chloride''' is an [[organic compound]] with formula [CoCl<sub>2</sub>(en)<sub>2</sub>]Cl (en = [[ethylenediamine]]). It is a violet diamagnetic solid that is soluble in water. One chloride ion in this salt readily undergoes ion exchange but the two other chlorides are less reactive, being bound to the metal center. |
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| title = Supramolecular Chemistry, 2nd edition |
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| url = https://archive.org/details/supramolecularch00stee |
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| url-access = limited |
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| chapter = |
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| author1 = Jonathan W. Steed |
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| author2 = Jerry L. Atwood |
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| publisher = Wiley |
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| year = 2009 |
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| isbn = 978-0-470-51233-3 |
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| page = [https://archive.org/details/supramolecularch00stee/page/n839 808] |
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}}</ref> Chloro(pyridine)cobaloxime is a yellow-brown powder that is sparingly soluble in most solvents, including water. |
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== |
==Structure== |
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The complex adopts a distorted octahedral geometry. Cobalt(III) is bound to two dimethylglyoximate ligands, i.e., mono-deprotonated [[dimethylglyoxime]], in the equatorial plane. Completing the coordination sphere are [[chloride]] and a [[pyridine]] at the axial positions.<ref name="X-ray structure">{{cite journal |
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''Cis''-Dichlorobis(ethylenediamine)cobalt(III) chloride is obtained by heating ''trans''-[CoCl<sub>2</sub>(en)<sub>2</sub>]Cl e.g. using a steam bath. The trans isomer is in turn synthesized by the reaction of [[cobalt chloride]] and [[ethylenediamine]] in hydrochloric acid in the presence of oxygen: |
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| last1 = Geremia |
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:4 CoCl<sub>2</sub> + 8 en + 4 HCl + O<sub>2</sub> → 4 ''trans''-[CoCl<sub>2</sub>(en)<sub>2</sub>]Cl + 2 H<sub>2</sub>O |
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| first1 = Silvano |
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The initial product contains HCl, which is removed by heating. Alternatively, (carbonato)bis(ethylenediamine)cobalt (III) chloride reacts with hydrochloric acid at 10 °C to give the same species.<ref>Springbørg, J.; Schaffer, C.E. “Dianionobis(Ethylenediamine)Cobalt (III) Complexes” Inorganic Synthesis, 1973; volume 14, pages 63-77. {{DOI|10.1002/9780470132456.ch14}}</ref> |
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| last2 = Dreos |
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:[Co(CO<sub>3</sub>)en<sub>2</sub>)]Cl + 2 HCl → ''trans''-[CoCl<sub>2</sub>(en)<sub>2</sub>]Cl + CO<sub>2</sub> + H<sub>2</sub>O |
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| first2 = Renata |
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| last3 = Randaccio |
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| first3 = Lucio |
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| last4 = Tauzher |
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| first4 = Giovanni |
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| date=February 1994 |
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| title = Evidence of the interaction between steric and electronic influence in rhodoximes and cobaloximes. Synthesis of pyRh(DH)2I and X-ray structure of pyRh(DH)2Cl and pyRh(DH)2I |
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| journal =Inorganica Chimica Acta |
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| volume = 216 |
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| issue = 1–2 |
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| pages =125–129 |
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| location = Trieste, Italy |
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| publisher = Elsevier B.V. |
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| doi=10.1016/0020-1693(93)03708-I |
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}}</ref> |
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==Reactions== |
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==Optical resolution== |
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The cobaloxime is slowly decomposed by acids and bases. With acids, the products of decomposition are dimethylglyoxime, cobalt salts, and pyridine; with bases, derivatives of other cobaloximes are formed, usually with the release of chloride ions. |
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The cis isomer is formed as a [[racemate]], which can be [[chiral resolution|resolved]] into two [[enantiomer]]s (Λ and Δ) by the formation of the ''d''-α-bromocamphor-π-sulfonate salt. The [[diastereomer]]ic salts are separated by recrystallization. After their purification, the individual diastereomers are converted back to the chloride salt by reaction with ice cold hydrochloric acid.<ref>[[John C. Bailar|Bailar]], J.C. “Cis- and Trans-Dichlorobis-(Ethylenediamine) Cobalt (III) Chloride and the Resolution of the Cis Form”. Inorganic Synthesis, 1946, volume 2, pages 222-225. {{DOI|10.1002/9780470132333.ch71}}</ref> |
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<center> |
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<gallery> |
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Image:Delta-cis-dichlorobis(ethylenediamine)cobalt(III).png|<center>[[cis-Dichlorobis(ethylenediamine)cobalt(III) chloride|Λ-''cis''-[CoCl<sub>2</sub>(en)<sub>2</sub>]<sup>+</sup>]]</center> |
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Image:Lambda-cis-dichlorobis(ethylenediamine)cobalt(III).png|<center>Δ-''cis''-[CoCl<sub>2</sub>(en)<sub>2</sub>]<sup>+</sup></center> |
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</gallery> |
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</center> |
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The complex has no reaction with [[hydrogen]] gas, and cannot carry oxygen as [[salcomine]] does. It would, however, react with hydrogen in the presence of [[sodium hydroxide]], a catalytic amount of [[platinum]] metal, or a reduced cobaloxime, therefore once the reduction occurs, the hydrogenation would occur much more rapidly as there is [[autocatalysis]]. |
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==Comparison of cis and trans isomers== |
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This salt is less soluble than the dull-green isomeric ''trans''-Dichlorobis(ethylenediamine)cobalt(III) chloride (CAS#14040-33-6). This pair of isomers were significant in the development of the area of [[coordination chemistry]].<ref>Jörgensen, S.M. “Ueber Metalldiaminverbindungen“ J. prakt. Chem., 1889, volume 39, page 8. {{DOI|10.1002/prac.18890390101}}</ref> The chiral cis isomer can be obtained by heating the trans isomer. Both isomers of dichlorobis(ethylenediamine)cobalt(III) chloride have often used in stereochemical studies and as intermediates (like [[Tris(ethylenediamine)cobalt(III) chloride]]) for the preparation of other cobalt salt complexes. |
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The reduction products of cobaloxime depends on the conditions. At pH near 7, a cobaloxime with a Co<sup>II</sup> center is formed. With a higher pH, the cobalt center would be further reduced to the Co<sup>I</sup> state, which is [[nucleophile|supernucleophilic]].<ref name="InorgSyn" /> |
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==Properties of the trans isomer== |
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Crystallographic analysis shows that the trans isomer has the following bond distances: Co-N: 1.99, Co-Cl: 2.22, C-N: 1.47, C-C 1.54 Å.<ref>Sharma, R. J.; Sharma, R.; Bala, R; Salas, J. M.; Quiros, M. “Second sphere coordination complexes via hydrogen bonding: Synthesis, spectroscopic characterisation of [trans-Co(en)<sub>2</sub>Cl<sub>2</sub>]CdX<sub>4</sub> (X=Br or I) and single crystal X-ray structure determination of [trans-Co(en)<sub>2</sub>Cl<sub>2</sub>]CdBr<sub>4</sub>” Journal of Molecular Structure, 2006, volume 794, pages 342-344. {{DOI|10.1016/j.molstruc.2006.02.053}}</ref> The trans isomer cation has idealized D<sub>2h</sub> point group symmetry, whereas the cis isomer cation has C<sub>2</sub> symmetry. |
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== |
==Preparation== |
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The compound is usually prepared by mixing [[cobalt(II) chloride]], dimethylglyoxime and pyridine in an ethanolic solution. This process afford the cobaloxime(II), which is subsequently oxidized by the oxygen in air:<ref name="InorgSyn" /> |
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<references/> |
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: 4 CoCl<sub>2</sub>•6H<sub>2</sub>O + 8 [[dimethylglyoxime|dmgH<sub>2</sub>]] + 8 [[pyridine|py]] + O<sub>2</sub> → 4 ClCo(dmgH)<sub>2</sub>py + 4 [[pyridinium chloride|py•HCl]] + 14 H<sub>2</sub>O |
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{{DEFAULTSORT:Dichlorobis(ethylenediamine)cobalt(III) chloride, cis}} |
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Using [[cobalt(II) acetate]] in place of [[cobalt(II) chloride]] produce aceto(pyridine)cobaloxime. This acetate can be converted to the respective [[bromide]], [[iodide]], [[cyanate]], [[cyanide]], [[azide]] and [[thiocyanate]].<ref name="InorgSyn" /> |
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[[Category:Cobalt compounds]] |
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: (CH<sub>3</sub>COO)Co(DH)<sub>2</sub>py + NaX → XCo(DH)<sub>2</sub>py + NaCH<sub>3</sub>COO (X = Br, I, CNO, CN, N<sub>3</sub> or SCN) |
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[[Category:Chlorides]] |
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[[Category:Metal halides]] |
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==Reactions== |
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[[Category:Coordination compounds]] |
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The pyridine base in the axial position can also be replaced by other organic bases containing a ''sp''<sup>2</sup> hybridized N atom as well. Commonly used bases are [[morpholine]], [[4-methylpyridine]], [[imidazole]] and [[benzimidazole]]. The derivatives are again prepared via diacetocobaloxime, followed by the addition of the desired base, such as imidazole. |
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: (CH<sub>3</sub>COO)<sub>2</sub>Co(DH)<sub>2</sub> + [[imidazole|imi]] → (CH<sub>3</sub>COO)Co(DH)<sub>2</sub>imi |
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===Alkylation of Co=== |
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One of the methods used for producing the Co-C bond is to make use of the supernucleophilicity of the Co<sup>I</sup> center. Chloro(pyridine)cobaloxime(III) is first reduced to Chloro(pyridine)cobaloxime(I) by [[sodium borohydride]] in alkaline solution, then an alkyl halide is added into the reaction mixture, and the desired Co-C bond is formed via a [[nucleophilic substitution|S<sub>N</sub>2]] reaction. This method can be used to produce cobaloximes containing a primary or a secondary alkyl substituent. |
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For derivatives with phenyl or vinyl substituent, the [[Grignard reaction]] is employed. However, since the dimethylglyoxime ligands contains two acidic H atoms in the [[oxime]] group, the Grignard reagent must be used in three-fold excess to compensate the loss.<ref name="InorgSyn">{{cite book |
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| author = G. N. Schrauzer |
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| title = Bis(dimethylglyoximato)cobalt complexes (Cobaloximes) - A. Chloro(pyridine)cobaloxime(III) |
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| series = Inorganic Syntheses |
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| year = 1968 |
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| volume = XI |
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| pages = 62–64 |
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| doi = 10.1002/9780470132425 |
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| isbn = 9780470132425| doi-access = free |
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}}</ref> |
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==References== |
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{{reflist}} |
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[[Category:Coordination complexes]] |
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[[Category:Cobalt complexes]] |
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[[Category:Cobalt(III) compounds]] |
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[[Category:Ketoximes]] |
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[[Category:Pyridine complexes]] |
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