Tris(ethylenediamine)cobalt(III) chloride is an inorganic compound with the formula [Co(en)3]Cl3 (where "en" is the abbreviation for ethylenediamine). It is the chloride salt of the coordination complex [Co(en)3]3+. This trication was important in the history of coordination chemistry because of its stability and its stereochemistry. Many different salts have been described. The complex was first described by Alfred Werner who isolated this salt as yellow-gold needle-like crystals.[1]
The compound is prepared from an aqueous solution of ethylenediamine and virtually any cobalt(II) salt, such as cobalt(II) chloride. The solution is purged with air to oxidize the cobalt(II)-ethylenediamine complexes to cobalt(III). The reaction proceeds in 95% yield, and the trication can be isolated with a variety of anions. A detailed product analysis of a large-scale synthesis revealed that one minor by-product was [Co(en)2Cl(H2NCH2CH2NH3)]Cl3, which contains a rare monodentate ethylenediamine ligand (protonated).[2]
The cation [Co(en)3]3+ is octahedral with Co-N distances in the range 1.947–1.981 Å. The N-Co-N angles are 85° within the chelate rings and 90° between nitrogen atoms on adjacent rings.[3]
Stereochemistryedit
Structure of the Δ-(lel)3 (or Δ-(λλλ)) isomer of [Co(en)3]3+. One of the three C2 symmetry axes is shown in red.
The point group of this complex is D3. The complex can be resolved into enantiomers that are described as Δ and Λ. Usually the resolution entails use of tartrate salts.[4] The optical resolution is a standard component of inorganic synthesis courses.[5] Because of its nonplanarity, the MN2C2 rings can adopt either of two conformations, which are described by the symbols λ and δ. The registry between these ring conformations and the absolute configuration of the metal centers is described by the nomenclature lel (when the en backbone lies parallel with the C3 symmetry axis) or ob (when the en backbone is obverse to this same C3 axis). Thus, the following diastereomeric conformations can be identified: Δ-(lel)3, Δ-(lel)2(ob), Δ-(lel)(ob)2, and Δ-(ob)3. The mirror images of these species of course exist also.[6]
Hydratesedit
Cationic coordination complexes of ammonia and alkyl amines typically crystallize with water in the lattice, and the stoichiometry can depend on the conditions of crystallization and, in the cases of chiral complexes, the optical purity of the cation. Racemic [Co(en)3]Cl3 is most often obtained as the di- or trihydrate. For the optically pure salt (+)-[Co(en)3]Cl3·1.5H2O, (+)-[Co(en)3]Cl3·0.5NaCl·3H2O, and (+)-[Co(en)3]Cl3·H2O are also known.[3]
Referencesedit
^A. Werner (1912). "Zur Kenntnis des asymmetrischen Kobaltatoms. V". Chemische Berichte. 45 (1): 121–130. doi:10.1002/cber.19120450116.
^Jack M. Harrowfield; Mark I. Ogden; Brian W. Skelton; Allan H. White (2005). "Alfred Werner Revisited: Some Subtleties of Complex Ion Synthesis and Isomerism". Comptes Rendus Chimie. 8 (2): 121–128. doi:10.1016/j.crci.2004.10.013. hdl:20.500.11937/8231.
^ abD. Witiak, J. C. Clardy, and D. S. Martin, Jnr. (1972). "The Crystal Structure of (+)-D-Tris(ethylenediamine)cobalt(III) Nitrate". Acta Crystallographica. B28 (9): 2694–2699. Bibcode:1972AcCrB..28.2694W. doi:10.1107/S056774087200679X.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^J. A. Broomhead; F. P. Dwyer; J. W. Hogarth (1960). "Resolution of the Tris(Ethylenediamine)Cobalt(III) Ion". Inorganic Syntheses. Vol. VI. pp. 183–186. doi:10.1002/9780470132371.ch58. ISBN978-0-470-13237-1.
^Girolami, G. S.; Rauchfuss, T. B. and Angelici, R. J., Synthesis and Technique in Inorganic Chemistry, University Science Books: Mill Valley, CA, 1999 ISBN0-935702-48-2
^von Zelewsky, A. "Stereochemistry of Coordination Compounds" John Wiley: Chichester, 1995 ISBN047195599X.
May 08, 2024
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Tris ethylenediamine cobalt III chloride is an inorganic compound with the formula Co en 3 Cl3 where en is the abbreviation for ethylenediamine It is the chloride salt of the coordination complex Co en 3 3 This trication was important in the history of coordination chemistry because of its stability and its stereochemistry Many different salts have been described The complex was first described by Alfred Werner who isolated this salt as yellow gold needle like crystals 1 Tris ethylenediamine cobalt III chloride Names IUPAC name cobalt tris ethylenediamine chloride Other names tris ethylenediamine cobalt III chloride Identifiers CAS Number 207802 43 5 Y 3D model JSmol Interactive imagedihydrate Interactive imagetrihydrate Interactive image ChemSpider 147079 PubChem CID dihydrate 71311392trihydrate 73995044 CompTox Dashboard EPA dihydrate DTXSID10746548 InChI InChI 1S 3C2H8N2 3ClH Co c3 3 1 2 4 h3 1 4H2 3 1H q 3 p 3Key NFUAZJFARNNNFB UHFFFAOYSA Kdihydrate InChI 1S 3C2H8N2 3ClH Co 2H2O c3 3 1 2 4 h3 1 4H2 3 1H 2 1H2 q 3 p 3Key ALLUKJGRPOLBEF UHFFFAOYSA Ktrihydrate InChI 1S 3C2H8N2 3ClH Co 3H2O c3 3 1 2 4 h3 1 4H2 3 1H 3 1H2 q 3 p 3Key WBMVTRUQSMZIKW UHFFFAOYSA K SMILES C CN N C CN N C CN N Cl Cl Cl Co 3 dihydrate C CN N C CN N C CN N O O Cl Co Cl Cltrihydrate C CN N C CN N C CN N O O O Cl Cl Cl Co 3 Properties Chemical formula C6H24N6Cl3Co Molar mass 345 59 Appearance yellow orange solid Melting point 275 C 527 F 548 K decomposes Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references Contents 1 Synthesis and structure 2 Stereochemistry 3 Hydrates 4 ReferencesSynthesis and structure editThe compound is prepared from an aqueous solution of ethylenediamine and virtually any cobalt II salt such as cobalt II chloride The solution is purged with air to oxidize the cobalt II ethylenediamine complexes to cobalt III The reaction proceeds in 95 yield and the trication can be isolated with a variety of anions A detailed product analysis of a large scale synthesis revealed that one minor by product was Co en 2Cl H2NCH2CH2NH3 Cl3 which contains a rare monodentate ethylenediamine ligand protonated 2 The cation Co en 3 3 is octahedral with Co N distances in the range 1 947 1 981 A The N Co N angles are 85 within the chelate rings and 90 between nitrogen atoms on adjacent rings 3 Stereochemistry edit nbsp Structure of the D lel 3 or D lll isomer of Co en 3 3 One of the three C2 symmetry axes is shown in red The point group of this complex is D3 The complex can be resolved into enantiomers that are described as D and L Usually the resolution entails use of tartrate salts 4 The optical resolution is a standard component of inorganic synthesis courses 5 Because of its nonplanarity the MN2C2 rings can adopt either of two conformations which are described by the symbols l and d The registry between these ring conformations and the absolute configuration of the metal centers is described by the nomenclature lel when the en backbone lies parallel with the C3 symmetry axis or ob when the en backbone is obverse to this same C3 axis Thus the following diastereomeric conformations can be identified D lel 3 D lel 2 ob D lel ob 2 and D ob 3 The mirror images of these species of course exist also 6 Hydrates editCationic coordination complexes of ammonia and alkyl amines typically crystallize with water in the lattice and the stoichiometry can depend on the conditions of crystallization and in the cases of chiral complexes the optical purity of the cation Racemic Co en 3 Cl3 is most often obtained as the di or trihydrate For the optically pure salt Co en 3 Cl3 1 5H2O Co en 3 Cl3 0 5NaCl 3H2O and Co en 3 Cl3 H2O are also known 3 References edit A Werner 1912 Zur Kenntnis des asymmetrischen Kobaltatoms V Chemische Berichte 45 1 121 130 doi 10 1002 cber 19120450116 Jack M Harrowfield Mark I Ogden Brian W Skelton Allan H White 2005 Alfred Werner Revisited Some Subtleties of Complex Ion Synthesis and Isomerism Comptes Rendus Chimie 8 2 121 128 doi 10 1016 j crci 2004 10 013 hdl 20 500 11937 8231 a b D Witiak J C Clardy and D S Martin Jnr 1972 The Crystal Structure of D Tris ethylenediamine cobalt III Nitrate Acta Crystallographica B28 9 2694 2699 Bibcode 1972AcCrB 28 2694W doi 10 1107 S056774087200679X a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link J A Broomhead F P Dwyer J W Hogarth 1960 Resolution of the Tris Ethylenediamine Cobalt III Ion Inorganic Syntheses Vol VI pp 183 186 doi 10 1002 9780470132371 ch58 ISBN 978 0 470 13237 1 Girolami G S Rauchfuss T B and Angelici R J Synthesis and Technique in Inorganic Chemistry University Science Books Mill Valley CA 1999 ISBN 0 935702 48 2 von Zelewsky A Stereochemistry of Coordination Compounds John Wiley Chichester 1995 ISBN 047195599X Retrieved from https en wikipedia org w index php title Tris ethylenediamine cobalt III chloride amp 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