Xiao-Juan Yang, C. Janiak, J. Heinze
Jun 18, 2001
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0
Influential Citations
41
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Journal
Inorganica Chimica Acta
Abstract
The optical absorption and luminescence spectra, the electrochemical behavior, and the X-ray crystal structure of a series of three heteroleptic Ru(II) complexes in comparison to [Ru(bipy)3] 2 + are reported. The complexes examined are of the type [Ru(bipy)2(bipy)](PF6)2 with bipy =2,2-bipyridine and bipy= 5,5-diamino-2,2-bipyridine (4), diethyl-2,2-bipyridine-5,5-dicarboxylate (5 )o r 5,5-bis(ethoxycarbonylamino)-2,2-bipyridine (6). Absorption bands and redox waves are fully assigned. The position of bands or half-wave potentials can be correlated with the electron-withdrawing/donating properties of the bipy ligand. The relative emission intensities of complexes with 4 and 6 can be modulated through the hydrogen-bonding capabilities of the solvent (MeOH and H2O). The cyclic voltammograms between + 1.5 and − 2.2 V show a reversible metal-oxidation wave and two to four reduction waves, attributed to successive reductions of the different ligands. Ligand 4 can only be oxidized. Correlations between spectroscopical and electrochemical data give a linear relation for h max ,h max versus E1/2. A comparison with complexes with the analogous 4,4-disubstituted-2,2-bipyridine ligands reveals pronounced differences in the position of the MLCT-absorption and emission bands due to the 5- or 4-position of the substituent. © 2001 Elsevier Science B.V. All rights reserved.