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Mix and match : templating chiral Schiff base ligands to suit the needs of the metal ion

Constable, Edwin C. and Zhang, Guoqi and Housecroft, Catherine E. and Zampese, Jennifer A.. (2010) Mix and match : templating chiral Schiff base ligands to suit the needs of the metal ion. Dalton Transactions, 39. pp. 5332-5340.

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Official URL: http://edoc.unibas.ch/dok/A5841494

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Abstract

One-pot reactions of 2,2′-bipyridine-6-carbaldehyde, (1S,2S)-(−)-1,2-diphenyl-1,2-diaminoethane and FeCl2·4H2O or Zn(OAc)2·2H2O (2[thin space (1/6-em)]:[thin space (1/6-em)]1[thin space (1/6-em)]:[thin space (1/6-em)]1) at room temperature in MeOH lead to [Fe{(S,S)-5}2][PF6]Cl or [Zn{(S,S)-5}2][PF6]2 in which (S,S)-5 contains an imidazolidine ring, produced by intramolecular cyclization. This has been confirmed with the single-crystal structure of 2{P-[Fe{(S,S)-5}2][PF6]Cl}·H2O. The diastereoselectivity observed in the solid state has been confirmed by NMR spectroscopy for solutions of [Fe{(S,S)-5}2][PF6]Cl and [Zn{(S,S)-5}2][PF6]2. At room temperature, a minor product competes with the formation of [Fe{(S,S)-5}2][PF6]Cl, and the preference for these complexes is switched by carrying out the reaction in MeOH at reflux. In this case the major product is M-[Fe2{(S,S)-4}2][PF6]4 in which (S,S)-4 is the hexadentate Schiff base ligand formed by condensation of two equivalents of 2,2′-bipyridine-6-carbaldehyde with (1S,2S)-(−)-1,2-diphenyl-1,2-diaminoethane; the single-crystal structure of 4{M-[Fe2{(S,S)-4}2][PF6]4}·8Me2CO·5MeCN·3H2O confirms the assembly of a double helicate. When pyridine-6-carbaldehyde replaces 2,2′-bipyridine-6-carbaldehyde in the iron(II)-templated reaction with (1S,2S)-(−)-1,2-diphenyl-1,2-diaminoethane, the product is [Fe{(S,S)-7}2][PF6]2 (3[thin space (1/6-em)]:[thin space (1/6-em)]2 mixture of diastereoisomers in solution) in which (S,S)-7 is an asymmetrical Schiff base, formed by reaction of only one of the amine groups in (1S,2S)-(−)-1,2-diphenyl-1,2-diaminoethane. The solid state structure of P-[Fe{(S,S)-7}2][PF6]2·MeCN is presented.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)
UniBasel Contributors:Housecroft, Catherine Elizabeth and Constable, Edwin Charles and Zhang, Guoqi and Zampese, Jennifer Ann
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
ISSN:1477-9226
e-ISSN:1477-9234
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:08 May 2017 07:26
Deposited On:14 Sep 2012 06:53

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