0181774 - UFCH-W 20030213 RIV GB eng J - Journal Article
Frantz, S. - Reinhardt, R. - Greulich, S. - Wanner, M. - Fiedler, Jan - Duboc-Toia, C. - Kaim, W.
Multistep Redox Sequences of Azopyridyl (L) Bridged Reaction Centres in Stable Radical Complex Ions {(.mu.-L)[MCl(.eta.5-C5Me5)]2}.+, M = Rh or Ir: Spectroelectrochemistry and High-frequency EPR Spectroscopy.
Dalton Transactions. č. 18 (2003), s. 3370-3375. ISSN 1477-9226. E-ISSN 1477-9234
R&D Projects: GA ČR GA203/03/0821; GA MŠMT OC D15.10
Institutional research plan: CEZ:AV0Z4040901
Keywords : EPR spectroscopy * radical complex ions
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 2.908, year: 2003

The tppz-bridged diruthenium complex [{(L)ClRuII}(2)(mu-tppz)](ClO4)(2), [1](ClO4), {tppz=2,3,5,6-tetrakis(2-pyridyl)-pyrazine, L=2,2''-dipyridylamine} and its mononuclear counterpart [(L)ClRuII(tppz)]ClO4, [2](ClO4) have been synthesized. The 380 mV separation between successive Ru-II/Ru-III couples in [1](2+) leads to a comproportionation constant (K-c) of 2.7x10(6). Consequently, the (RuRuIII)-Ru-II species [1](3+) exhibits a rather narrow intervalence charge transfer band at 1700 run, suggesting a class III mixed-valence state, the electronic coupling constant (V-ab) is calculated at 2940 cm(-1). Complex [1](3+) displays a rhombic EPR spectrum at 4 K (g(1)=3.390, g(2)=2.278, g(3)=1.697), characteristic of ruthenium(III) in a distorted octahedral environment. Both complexes show two successive tppz-based reduction processes [(tppz)(0/-1) and (tppz)(-1/-2)].
Permanent Link: http://hdl.handle.net/11104/0078295