Ru-II(alpha-diimine) or Ru-III(alpha-diimine(center dot-))? Structural, Spectroscopic, and Theoretical Evidence for the Stabilization of a Prominent Metal-to-Ligand Charge-Transfer Excited-State Configuration in the Ground State

0428321 - ÚFCH JH 2015 RIV DE eng J - Článek v odborném periodiku
Grupp, A. - Bubrin, M. - Ehret, F. - Zeng, Q. - Hartl, F. - Kvapilová, Hana - Záliš, Stanislav - Kaim, W.
Ru-II(alpha-diimine) or Ru-III(alpha-diimine(center dot-))? Structural, Spectroscopic, and Theoretical Evidence for the Stabilization of a Prominent Metal-to-Ligand Charge-Transfer Excited-State Configuration in the Ground State.
European Journal of Inorganic Chemistry. Roč. 2014, č. 1 (2014), s. 110-119. ISSN 1434-1948. E-ISSN 1099-0682
Grant CEP: GA MŠMT LD11086
Institucionální podpora: RVO:61388955
Klíčová slova: N ligands * Noninnocent ligands * Oxidation states
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 2.942, rok: 2014

The new compounds [Ru(R-DAB)(acac)(2)] (R-DAB = 1,4-diorganyl-1,4-diazabuta-1,3-diene; R = tert-butyl, 4-methoxyphenyl, 2,6-dimethylphenyl; acac(-) = 2,4-pentanedionate) exhibit intrachelate ring bond lengths 1.297<d(CN)<1.344 angstrom and 1.382<d(CC)<1.425 angstrom, which suggest a Ru-III(R-DAB(-)) oxidation state formulation. This notion is confirmed by the negligible solvatochromism of the intense (E approximate to 10(4) M(-1)cm(-1)) charge-transfer absorption band in the visible region and by DFT calculations. Oxidation of the compounds occurs mainly at the R-DAB(-) radical ligand to produce UV/Vis/NIR and electron paramagnetic resonance (EPR) spectroelectrochemically detectable Ru-III species, whereas the reduction proceeds less reversibly and yields predominantly (R-DAB)-ligand-based spin for the 4-methoxyphenyl derivative, measured at low temperature. The results are discussed with respect to metal-to-ligand charge-transfer (MLCT) excited states of conventional (-diimine)ruthenium(II) complexes and in view of other (-diimine)metal complexes with ambiguous oxidation-state assignments.
Trvalý link: http://hdl.handle.net/11104/0233677