%0 Journal Article %1 Hornung.1998 %A Hornung, Fridmann M. %A Baumann, Frank %A Kaim, Wolfgang %A Olabe, Jose A. %A Slep, Leonardo D. %A Fiedler, Jan. %D 1998 %J Inorganic Chemistry %K charge cyano dinuclear dinuclear;electrochem dinuclear;osmium osmium oxidn prepn pyrazine spectra spectroelectrochem transfer %N 2 %P 311--316 %R 10.1021/IC970804O %T Spectroelectrochemical Characterization of the Two-Step Redox System (μ-pz)[Os(CN)5]2n- (n = 4, 5, 6; pz = Pyrazine). Similarities and Differences in Relation to the Creutz-Taube System %V 37 %X The pyrazine-bridged diosmium(II) complex (μ-C4H4N2)[Os(CN)5]26- was synthesized as the hexapotassium salt and was converted to the Bu4N+ salt compd. by ion exchange. Its stepwise oxidn. to the OsIII2OsII and OsIII2OsIII states was monitored spectroelectrochem. in MeCN/0.1 M Bu4NPF6 in the UV-visible-NIR and IR regions and by EPR. The OsII2 species exhibits long-wavelength solvatochromic MLCT bands at 14,800 and 18,480 cm-1. The pentaanionic mixed-valent ion has a comproportionation const. Kc of 105.8 and is distinguished by several electronic absorptions in the IR region. The bands at 1970, 2480, 4000, 5000, 7170, and 11,900 cm-1 are similar but appreciably lower in energy than those reported for the analogous complex (μ-C4H4N2)[Os(NH3)5]25+. In addn. to CN vibrational stretching features shifted on electron transfer there is an addnl. sharp band only for the 5- ion at 1582 cm-1 which is attributed to a pyrazine ring vibration. The intensity of this band suggests an unsym. situation and thus valence localization on the vibrational time scale. The EPR signals at g$\bot$ = 2.0563 and g‖ = 1.761 point toward excited states lying close to the doublet ground state and to significant metal/cyanide interaction. Compared to the Creutz-Taube ion (μ-C4H4N2)[Ru(NH3)5]25+ and its Os homolog, the 5- ion described here exhibits a lower degree of metal-metal coupling. [on SciFinder(R)]

@article{Hornung.1998, abstract = {The pyrazine-bridged diosmium(II) complex {(μ-C4H4N2)[Os(CN)5]2}6- was synthesized as the hexapotassium salt and was converted to the Bu4N+ salt compd. by ion exchange. Its stepwise oxidn. to the OsIII2OsII and OsIII2OsIII states was monitored spectroelectrochem. in MeCN/0.1 M Bu4NPF6 in the UV-visible-NIR and IR regions and by EPR. The OsII2 species exhibits long-wavelength solvatochromic MLCT bands at 14,800 and 18,480 cm-1. The pentaanionic mixed-valent ion has a comproportionation const. Kc of 105.8 and is distinguished by several electronic absorptions in the IR region. The bands at 1970, 2480, 4000, 5000, 7170, and 11,900 cm-1 are similar but appreciably lower in energy than those reported for the analogous complex {(μ-C4H4N2)[Os(NH3)5]2}5+. In addn. to CN vibrational stretching features shifted on electron transfer there is an addnl. sharp band only for the 5- ion at 1582 cm-1 which is attributed to a pyrazine ring vibration. The intensity of this band suggests an unsym. situation and thus valence localization on the vibrational time scale. The EPR signals at g$\bot$ = 2.0563 and g‖ = 1.761 point toward excited states lying close to the doublet ground state and to significant metal/cyanide interaction. Compared to the Creutz-Taube ion {(μ-C4H4N2)[Ru(NH3)5]2}5+ and its Os homolog, the 5- ion described here exhibits a lower degree of metal-metal coupling. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Hornung, Fridmann M. and Baumann, Frank and Kaim, Wolfgang and Olabe, Jose A. and Slep, Leonardo D. and Fiedler, Jan.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/261a3027331a4e00bf7609eb4df8ec796/huebleriac}, doi = {10.1021/IC970804O}, interhash = {057634afbb06e23404b862562371db5c}, intrahash = {61a3027331a4e00bf7609eb4df8ec796}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {charge cyano dinuclear dinuclear;electrochem dinuclear;osmium osmium oxidn prepn pyrazine spectra spectroelectrochem transfer}, number = 2, pages = {311--316}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Spectroelectrochemical Characterization of the Two-Step Redox System {(μ-pz)[Os(CN)5]2}n- (n = 4, 5, 6; pz = Pyrazine). Similarities and Differences in Relation to the Creutz-Taube System}, volume = 37, year = 1998 }