EPR Evidence for Low-Lying MLCT States in Tetracyanoiron and -ruthenium Complexes with Strongly p-Accepting Chelate Ligands. Comparison with Isoelectronic Tetracarbonylmetal Species
(Bpz)M(CN)42- (M = Fe, Ru) and (abpy)Fe(CN)42- with the strongly p-accepting chelate ligands 2,2'-bipyrazine (bpz) and 2,2'-azobis(pyridine) (abpy) were prepd. as potassium or tetrabutylammonium salts and were characterized by IR and UV/visible absorption spectroscopy. Cyclic voltammetry in acetonitrile, DMF, or water revealed reversible 1-electron oxidn. processes, while the redn. waves showed reversibility only in aprotic solvents. EPR studies of the spectroelectrochem. generated (1-) and (3-) states confirm the MLCT formulation for the lowest excited states of the (2-) precursor complexes by showing typical low-spin Fe(III) signals of the oxidized species (abpy)Fe(CN)4- and partially hyperfine-structured spectra for the reduced forms (bpz)M(CN)43-. The latter are clearly tetracyanoiron(II) or -ruthenium(II) complexes of the corresponding anion radical acceptor ligands and are thus isoelectronic with monoanionic tetracarbonylchromium(0) or -molybdenum(0) radial complexes. on SciFinder(R)
%0 Journal Article
%1 Waldhoer.1995
%A Waldhoer, Eberhard
%A Poppe, Juergen
%A Kaim, Wolfgang
%A Cutin, Edgardo H.
%A Garcia Posse, Monica E.
%A Katz, Nestor E.
%D 1995
%J Inorganic Chemistry
%K azobispyridine azobispyridine;ESR azobispyridine;electrochem bipyrazine charge complex;MLCT cyano cyano;iron iron redox ruthenium transfer
%N 11
%P 3093--3096
%R 10.1021/ic00115a042
%T EPR Evidence for Low-Lying MLCT States in Tetracyanoiron and -ruthenium Complexes with Strongly p-Accepting Chelate Ligands. Comparison with Isoelectronic Tetracarbonylmetal Species
%V 34
%X (Bpz)M(CN)42- (M = Fe, Ru) and (abpy)Fe(CN)42- with the strongly p-accepting chelate ligands 2,2'-bipyrazine (bpz) and 2,2'-azobis(pyridine) (abpy) were prepd. as potassium or tetrabutylammonium salts and were characterized by IR and UV/visible absorption spectroscopy. Cyclic voltammetry in acetonitrile, DMF, or water revealed reversible 1-electron oxidn. processes, while the redn. waves showed reversibility only in aprotic solvents. EPR studies of the spectroelectrochem. generated (1-) and (3-) states confirm the MLCT formulation for the lowest excited states of the (2-) precursor complexes by showing typical low-spin Fe(III) signals of the oxidized species (abpy)Fe(CN)4- and partially hyperfine-structured spectra for the reduced forms (bpz)M(CN)43-. The latter are clearly tetracyanoiron(II) or -ruthenium(II) complexes of the corresponding anion radical acceptor ligands and are thus isoelectronic with monoanionic tetracarbonylchromium(0) or -molybdenum(0) radial complexes. on SciFinder(R)
@article{Waldhoer.1995,
abstract = {[(Bpz)M(CN)4]2- (M = Fe, Ru) and [(abpy)Fe(CN)4]2- with the strongly \textgreek{p}-accepting chelate ligands 2,2'-bipyrazine (bpz) and 2,2'-azobis(pyridine) (abpy) were prepd. as potassium or tetrabutylammonium salts and were characterized by IR and UV/visible absorption spectroscopy. Cyclic voltammetry in acetonitrile, DMF, or water revealed reversible 1-electron oxidn. processes, while the redn. waves showed reversibility only in aprotic solvents. EPR studies of the spectroelectrochem. generated (1-) and (3-) states confirm the MLCT formulation for the lowest excited states of the (2-) precursor complexes by showing typical low-spin Fe(III) signals of the oxidized species [(abpy)Fe(CN)4]- and partially hyperfine-structured spectra for the reduced forms [(bpz)M(CN)4]3-. The latter are clearly tetracyanoiron(II) or -ruthenium(II) complexes of the corresponding anion radical acceptor ligands and are thus isoelectronic with monoanionic tetracarbonylchromium(0) or -molybdenum(0) radial complexes. [on SciFinder(R)]},
added-at = {2022-06-15T11:26:56.000+0200},
author = {Waldhoer, Eberhard and Poppe, Juergen and Kaim, Wolfgang and Cutin, Edgardo H. and {Garcia Posse}, Monica E. and Katz, Nestor E.},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/281850ec891415299ea0be8dcd0e869f7/huebleriac},
doi = {10.1021/ic00115a042},
interhash = {08bbb0e60c4711b4345ee5a00348ec3b},
intrahash = {81850ec891415299ea0be8dcd0e869f7},
issn = {0020-1669},
journal = {Inorganic Chemistry},
keywords = {azobispyridine azobispyridine;ESR azobispyridine;electrochem bipyrazine charge complex;MLCT cyano cyano;iron iron redox ruthenium transfer},
number = 11,
pages = {3093--3096},
timestamp = {2022-06-15T09:26:56.000+0200},
title = {EPR Evidence for Low-Lying MLCT States in Tetracyanoiron and -ruthenium Complexes with Strongly \textgreek{p}-Accepting Chelate Ligands. Comparison with Isoelectronic Tetracarbonylmetal Species},
volume = 34,
year = 1995
}