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Fine Tuning of MLCT States in New Mononuclear Complexes of Ruthenium(II) Containing Tris(1-pyrazolyl)methane, 2,2 -Bipyridine and Aromatic Nitrogen Heterocycles

The syntheses of new mononuclear ruthenium(II) complexes of the type: [Ru(bpy)(L)(tpm)](PF6)2 {tpm = tris(1-pyrazolyl)methane; bpy = 2,2′-bipyridine; L = pz (pyrazine; 1), 4,4′-bpy (4,4′-bipyridine; 2), and bpe [trans-1,2-bis(4-pyridyl)ethylene; 3]} are described, together with their spectroscopic, electrochemical, and photophysical properties. A complete assignment of the NMR resonances of the three species could be made in CD3CN by bidimensional techniques. A fine tuning of the energies of MLCT (metal-to-ligand charge transfer) states in these complexes is disclosed when comparing, in CH3CN, the values of their maximum absorption wavelengths for the most intense visible bands (λmax) and their redox potentials for the RuIII/RuII couples; this effect, relevant to the design of efficient photocatalysts, can be attributed to a decreasing order of dπ(Ru) → π*(2,2′-bpy) backbonding when decreasing the distance between both N atoms in the aromatic nitrogen heterocycle L that acts in a monodentate manner. Only the species with L = bpe emits at room temperature, pointing to the conclusion that MLCT excited states in this series become higher in energy than dd excited states when the value of λmax is lower than 400 nm. These species are also useful building blocks for new dinuclear mixed-valent complexes

This research has also been financed by MCYT of Spain through projects BQU2000-0458, BQU2003-02884, and BQU2003-01677. We would also like to thank the CIRIT Generalitat de Catalunya (Spain) for a Distinction award and the aid SGR2001-UG-291

© European Journal of Inorganic Chemistry, 2005, vol. 2005, núm. 2, p. 272-277

Wiley-VCH Verlag

Author: Katz, N.
Romero García, Isabel
Llobet Dalmases, Antoni
Parella Coll, Teodor
Benet Buchholz, Jordi
Date: 2005 January
Abstract: The syntheses of new mononuclear ruthenium(II) complexes of the type: [Ru(bpy)(L)(tpm)](PF6)2 {tpm = tris(1-pyrazolyl)methane; bpy = 2,2′-bipyridine; L = pz (pyrazine; 1), 4,4′-bpy (4,4′-bipyridine; 2), and bpe [trans-1,2-bis(4-pyridyl)ethylene; 3]} are described, together with their spectroscopic, electrochemical, and photophysical properties. A complete assignment of the NMR resonances of the three species could be made in CD3CN by bidimensional techniques. A fine tuning of the energies of MLCT (metal-to-ligand charge transfer) states in these complexes is disclosed when comparing, in CH3CN, the values of their maximum absorption wavelengths for the most intense visible bands (λmax) and their redox potentials for the RuIII/RuII couples; this effect, relevant to the design of efficient photocatalysts, can be attributed to a decreasing order of dπ(Ru) → π*(2,2′-bpy) backbonding when decreasing the distance between both N atoms in the aromatic nitrogen heterocycle L that acts in a monodentate manner. Only the species with L = bpe emits at room temperature, pointing to the conclusion that MLCT excited states in this series become higher in energy than dd excited states when the value of λmax is lower than 400 nm. These species are also useful building blocks for new dinuclear mixed-valent complexes
This research has also been financed by MCYT of Spain through projects BQU2000-0458, BQU2003-02884, and BQU2003-01677. We would also like to thank the CIRIT Generalitat de Catalunya (Spain) for a Distinction award and the aid SGR2001-UG-291
Format: application/pdf
Citation: https://doi.org/10.1002/ejic.200400487
ISSN: 1434-1948 (versió paper)
1099-0682 (versió electrònica)
Document access: http://hdl.handle.net/10256/13088
Publisher: Wiley-VCH Verlag
Collection: CICYT/PN 2000-2003/ BQU2000-0458
Reproducció digital del document publicat a: https://doi.org/10.1002/ejic.200400487
Is part of: © European Journal of Inorganic Chemistry, 2005, vol. 2005, núm. 2, p. 272-277
Rights: Tots els drets reservats
Subject: Ruteni -- Compostos
Ruthenium compounds
Title: Fine Tuning of MLCT States in New Mononuclear Complexes of Ruthenium(II) Containing Tris(1-pyrazolyl)methane, 2,2 -Bipyridine and Aromatic Nitrogen Heterocycles
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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