http://dx.doi.org/10.1021/om900253h">
 

Document Type

Journal Article

Department/Unit

Department of Chemistry

Title

Synthesis and photophysical properties of ruthenium(II) isocyanide complexes containing 8-Quinolinolate ligands

Language

English

Abstract

A series of ruthenium(II) bis(8-quinolinolato) complexes bearing isocyanide ligands (RNC) have been synthesized by the reaction of [RuQ3] (Q = 8-quinolinolate) with RNC in the presence of Zn/Hg. These complexes have the general formula [RuQ2(RNC)2] (1, R = tert-butyl; 2, R = 4-MeOPh; 3, R = 4-ClPh; 4, R = 2,4,6-Br3Ph). Both the yellow cis,cis,trans (a) and orange-red trans,trans,trans (b) isomers have been isolated for complexes 1-4. trans,trans,trans-[Ru(Tol-Q)2('BuNC)2] (6, HTol-Q = 8-hydroxyl-5-tolylquinoline) has also been prepared from [Ru(PPh3)2Cl2]. The structures of 2a, 3a, and 4b have been determined by X-ray crystallography. These complexes exhibit an intense absorption band in the UV region (λmax = 320-390 nm) with molar extinction coefficients (ε) on the order of 104 dm3 mol-1 cm-1 and a moderately intense absorption with e on the order of 103 dm3 mol-1 cm-1 at 400-492 nm. The intense absorption at 320- 390 nm is assigned to the ligand-centered π→π transitions of the quinolinolate ligands, probably mixed with the π→π transitions of the isocyanide ligands. The lower energy absorptions at 400-492 nm are assigned to Ru(dπ)→π(Q) metal-to-ligand charge transfer (MLCT) transitions. Upon excitation at λ > 350 nm, la-3a in dichloromethane solution exhibit orange-red luminescence (645-680 nm). In 77 K EtOH/MeOH glass, complexes 1-4 and 6 give intense structured emission spectra (593-638 nm). The cyclic voltammograms (CV) of 1a-4a generally exhibit an irreversible or quasi-reversible RuIII/II couple at the potential range of 0.02-0.38 V vs Fc+/Fc, except in the case of la, where a reversible Ru III/II and a quasi-reversible RuIV/III (0.68 V vs Fc+/Fc) couple are observed. The potential for the RuIII/II couple increases with the π-accepting ability of the isocyanide ligands. In the CV of 1b-4b, a reversible RuIII/II (-0.16 to 0.065 V) and quasi-reversible RuIV/III (0.70-0.85 V) couple are observed. © 2009 American Chemical. Society.

Publication Date

2009

Source Publication Title

Organometallics

Volume

28

Issue

19

Start Page

5709

End Page

5714

Publisher

American Chemical Society

ISSN (print)

02767333

ISSN (electronic)

15206041

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