Ruthenium(ii) Complexes of New Chelating Indolizino[2,3-b]pyrazine- and Indolizino[2,3-b]quinoxaline-Derived Ligands: Syntheses, Electrochemistry and Absorption Spectroscopy*

Christopher J. Sumby

doi:10.1071/CH08339

RESEARCH ARTICLE

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Ruthenium(ii) Complexes of New Chelating Indolizino[2,3-b]pyrazine- and Indolizino[2,3-b]quinoxaline-Derived Ligands: Syntheses, Electrochemistry and Absorption Spectroscopy*

Christopher J. Sumby ^A

+ Author Affiliations

- Author Affiliations

^A School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia. Email: christopher.sumby@adelaide.edu.au

Australian Journal of Chemistry 61(11) 894-904 https://doi.org/10.1071/CH08339
Submitted: 8 August 2008 Accepted: 29 September 2008 Published: 5 November 2008

Abstract

The highly conjugated chelating ligands 5-(2-pyridyl)indolizino[2,3-b]pyrazine 1, 5-(2-pyridyl)indolizino[2,3-b]quinoxaline 2, and 8,9-dimethyl-5-(2-pyridyl)indolizino[2,3-b]quinoxaline 3 were prepared in one step, with good yields, from di-2-pyridylmethane and 2,3-dichloropyrazine, 2,3-dichloroquinoxaline, and 8,9-dimethyl-2,3-dichloroquinoxaline, respectively. Compounds 1–3 display long-wavelength absorption maxima in the green (1) and yellow (2 and 3) to give intensely coloured red and purple solutions, respectively. Bis(2,2′-bipyridyl)ruthenium(ii) and bis(4,4′-dimethyl-2,2′-bipyridyl)ruthenium(ii) complexes were prepared in moderate to good yields, characterized by NMR spectroscopy and mass spectrometry, and studied by cyclic voltammetry and absorption spectroscopy. Copper(ii) and silver(i) nitrate complexes of the ligands were prepared and complexes [Cu(NO₃)₂(1)], [Cu(NO₃)₂(2)]₂, and [Ag(NO₃)(3)₂] were characterized by X-ray crystallography. These structures revealed the planar nature of the ligands and confirmed the proposed chelating mode.

^* Dedicated to Professor Michael I. Bruce on his retirement in recognition of his outstanding career and contributions to organometallic chemistry.

Acknowledgements

The author thanks Professor Peter Steel and Dr Jonathan Morris for helpful discussions, and the University of Adelaide for funding. Associate Professor Lyall Hanton is acknowledged for providing access to a diffractometer and stimulating discussions. The Australian Research Council is acknowledged for an Australian Post-Doctoral Fellowship.

References

Ruthenium(ii) Complexes of New Chelating Indolizino[2,3-b]pyrazine- and Indolizino[2,3-b]quinoxaline-Derived Ligands: Syntheses, Electrochemistry and Absorption Spectroscopy*

Abstract

Acknowledgements

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