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Keywords:

  • Ruthenium;
  • Back-to-back li­gands;
  • N ligands;
  • Bridging ligands

Abstract

Two (polypyridyl)ruthenium(II) complexes, [(tpy)RuII(L)](PF6)2 (1) and [(tpy)RuII(L)RuII(tpy)](PF6)4 (2) {tpy is 2,2′:6′,2″-terpyridine and L is 1,4-bis[(2,6-dipyrazol-1-yl)pyrid-4-yl]benzene}, were synthesised and studied in view of their electrochemical and photophysical properties. The structural characterisation of 1 and 2 was carried out by 1H and 13C NMR spectroscopy, MALDI-TOF/ESI mass spectrometry and single-crystal X-ray analysis. The spectro- and electrochemical consequences of the introduction of 2,6-dipyrazol-1-ylpyridine coordinating units into RuII polypyridyl complexes were investigated by UV/Vis, low-temperature emission spectroscopy and square-wave voltammetry. It was shown that ligand L can be used as a back-to-back bridging ligand in the construction of multinuclear ruthenium(II) ion arrays. In comparison to the widely used 2,2′:6′,2″-terpyridyl system, the 2,6-dipyrazol-1-ylpyrid-4-yl unit was found to act as a relatively strong σ-donor and weak π-acceptor ligand which allows its use as a structural and electronic alternative in multinuclear architectures.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)