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Stereochemistry controlled by an asymmetric sulfur atom, and a rare example of a kryptoracemate

Bouamaied, Imenne and Constable, Edwin C. and Housecroft, Catherine E. and Neuburger, Markus and Zampese, Jennifer A.. (2012) Stereochemistry controlled by an asymmetric sulfur atom, and a rare example of a kryptoracemate. Dalton Transactions, 41 (34). pp. 10276-10285.

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Official URL: http://edoc.unibas.ch/dok/A6056194

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Abstract

The ligands 4-methylthio-6-phenyl-2,2`-bipyridine (1) and the corresponding sulfoxide (2) and sulfone (3) have been synthesized and characterized in solution, and in the solid state by single crystal X-ray diffraction. Compounds 2 and 3 crystallize in the same space group (C2/c) with similar unit cell parameters; a small increase in the unit cell volume allows for the presence of the extra oxygen atom in 3. The sulfoxide and sulfone groups adopt conformations that permit intramolecular O center dot center dot HCaryl hydrogen bonds. The complexes [Ir(ppy)(2)L][PF6] with L = 1, 2 or 3 have been prepared and characterized. The asymmetric sulfur atom in ligand 2 gives rise to pairs of diastereoisomers of the complex which can be distinguished in the H-1 and C-13 NMR spectra. In solution, exchange of [PF6](-)by [Delta-TRISPHAT](-) gives rise to four diastereoisomers and we observed good dispersion of H-1 NMR resonances, especially for those assigned to protons close to the asymmetric sulfur atom. A single crystal X-ray diffraction study of 2[Ir(ppy)(2)(3)][PF6]center dot CHCl3 center dot 3H(2)O reveals that the complex crystallizes in the chiral space group P2(1)2(1)2(1), the asymmetric unit containing crystallographically independent Delta- and Lambda-[Ir(ppy)(2)(3)](+) cations. This provides a rare example of a so-called kryptoracemate in the solid state. In MeCN solution, [Ir(ppy)(2)(1)][PF6], [Ir(ppy)(2)(2)][PF6] and [Ir(ppy)(2)(3)][PF6] are weakly emissive (lambda(em) = 600, 647 and 672 nm, respectively) and preliminary studies of the electroluminescent properties of [Ir(ppy)(2)(2)][PF6] indicate that the complexes are not suitable candidates for LECs.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Constable)
05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)
UniBasel Contributors:Constable, Edwin Charles and Housecroft, Catherine Elizabeth
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:10 Apr 2017 13:59
Deposited On:01 Feb 2013 08:41

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