Protonation studies of reduced ruthenium(II) complexes with polypyridyl ligands

Citation
Pa. Anderson et al., Protonation studies of reduced ruthenium(II) complexes with polypyridyl ligands, INORG CHEM, 39(13), 2000, pp. 2721-2728
Citations number
55
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
INORGANIC CHEMISTRY
ISSN journal
00201669 → ACNP
Volume
39
Issue
13
Year of publication
2000
Pages
2721 - 2728
Database
ISI
SICI code
0020-1669(20000626)39:13<2721:PSORRC>2.0.ZU;2-U
Abstract
The pK(a) values associated with protonation of the one-electron reduced fo rms of series of [L'(2RuL)-L-II](2+) complexes {L' = bidentate polypyridyl ligand; L = bidentate polypyridyl ligand with additional uncoordinated N at oms in the aromatic ring system: e.g., dpp 2,3-bis(2-pyridyl)pyrazine, bpz = 2,2'-bipyrazine} were assessed using pulse radiolysis techniques by the m easurement of spectral variations as a function of pH. A linear correlation was observed between pK(a) and E degrees(RuL'L-2(2+/+)) for complexes in w hich the protonatable ligand was at the same time the site of reduction. In complexes where one or more of the nonprotonatable ligands (L') had very l ow pi* energy levels {e.g. (CF3)(4)bpy}, reduction occurs on a nonprotonata ble ligand and a dramatic decrease in the pK(a) values was observed fur the reduced species. In complexes where the energies of the protonatable and n onprotonatable ligands were comparable, the protonation behavior was consis tent with some orbital mixing/delocalization of the electronic charge.