Gold Complexes with Tridentate Cyclometalating and NHC Ligands: A Search for New Photoluminescent Gold(III) Compounds

Herbst, Annika and Bronner, Catherine and Dechambenoit, Pierre and Wenger, Oliver S.. (2013) Gold Complexes with Tridentate Cyclometalating and NHC Ligands: A Search for New Photoluminescent Gold(III) Compounds. Organometallics, 32 (6). pp. 1807-1014.

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Official URL: http://edoc.unibas.ch/dok/A6104449

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Many square-planar Pt(II) complexes are strongly photoluminescent, particularly when they contain cyclometalating and/or NHC ligands which produce strong ligand fields. In this work we investigated the possibility of obtaining isoelectronic Au(III) complexes with favorable luminescence properties. Toward this end, the coordination chemistry of gold with three different (potentially) tridentate ligands was explored: 1,3-bis(1-hexyl-2′-benzimidazoyl)benzene (L1H), 2,6-bis(3-butylimidazol-1-ium)pyridine (L2H22+), and 2,6-bis(3-hexylbenzimidazol-1-ium)pyridine (L3H22+). Pt(II) or Pd(II) complexes are known for all of these ligands or closely related analogues, and hence we anticipated that similar Au(III) complexes would be synthetically accessible as well. This turned out to be the case only for L1, despite exploration of different synthetic routes including (i) direct complexation of Au(III), (ii) transmetalation from Ag(I) precursor complexes, and (iii) transmetalation from suitable Hg(II) precursors. Only the mercury procedure was successful (at least in the case of L1); transmetalation from silver or direct complexation yields other reaction products containing Au(I) in most cases. Likewise, with ligands L2 and L3 mainly complexes of Au(I) were obtained: i.e., the propensity of gold for low oxidation states is a major obstacle to obtaining the desired Au(III) compounds. Several new complexes of Au(I) and Au(III) were characterized crystallographically. Our results provide insight into the differences between the coordination chemistry of isoelectronic Pt(II) and Au(III) with tridentate cyclometalating and NHC ligands.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Wenger)
UniBasel Contributors:Wenger, Oliver and Bronner, Catherine
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
Note:Publication type according to Uni Basel Research Database: Journal article -- The final publication is available at American Chemical Society, see DOI link
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Last Modified:11 Jun 2018 13:58
Deposited On:26 Apr 2013 06:57

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