Unkonventionelle gemischtvalente Komplexe des Rutheniums und Osmiums

Abstract

In den letzten Jahren ist es gelungen, das Repertoire gemischtvalenter Ruthenium‐ und Osmiumkomplexe über konventionelle Systeme hinaus zu erweitern, indem anspruchsvollere Liganden eingesetzt und vielgestaltigere Koordinationssituationen herbeigeführt wurden. Zu den angewendeten Strategien zählen sowohl die Nutzung mehrzähniger Liganden (die zu mehrkernigen Komplexen und Chelatkomplexen führen) als auch der Einsatz einer oder mehrerer selbst redoxaktiver Komponenten (“nicht‐unschuldige” Liganden; Stichwort: Oxidationsstufenambivalenz). Diese Untersuchungen geben tiefere Einblicke in die Abläufe von Elektronentransfers zwischen Metallen und Liganden. Gemischtvalente Materialien können in der molekularen Elektronik und im “molecular computing” Anwendung finden.

UncommoncisConfiguration of a Metal–Metal Bridging Noninnocent Nindigo Ligand

“…The 1:1 and 1:2 conducting compounds [1]ClO 4 and [2](ClO 4 ) 2 , respectively, gave satisfactory microanalytical and mass spectral data (Experimental Section and Figure S1 of the Supporting Information). 1 H NMR spectroscopy of [1]ClO 4 in (CD 3 ) 2 SO yields 34 partially overlapping proton resonances in the region of 5.0−9.0 ppm (18 and 16 protons of coordinated LH − and bpy, respectively), in addition to one NH(LH − ) proton signal at 11.5 ppm, corresponding to the full molecule ( Figure S2a of the Supporting Information and the Experimental Section). 1 H NMR spectroscopy of dinuclear complex [2](ClO 4 ) 2 in CDCl 3 yields 17 partially overlapping signals in the aromatic region [9(L) and 8(bpy)], one CH(acac) proton resonance, and two CH 3 (acac) proton resonances corresponding to the halfmolecule as expected from the meso (ΔΛ) diastereomeric form 12 ( Figure S2b of the Supporting Information and the Experimental Section).…”

“…The identities of [1]ClO 4 and [2](ClO 4 ) 2 have been authenticated by their single-crystal X-ray structures (Figures 1 and 2). Selected crystallographic and bond parameters are listed in Tables 1 and 2 and Tables S1−S4 of the Supporting Information, respectively.…”

“…Cyclic (black) and differential pulse (red) voltammograms of (a)[1]ClO 4 and (b) [2](ClO 4 ) 2 in CH 3 CN. Scan rate of 100 mV/s.…”

“…The crude product was purified by using a neutral alumina column. The pure brown complex corresponding to[1]ClO 4 was eluted with a 4:1 dichloromethane/acetonitrile mixture. Evaporation of the solvent…”

Structure, electrochemistry and spectroscopy of a new diacylhydrazido-bridged diruthenium complex with a strongly near-infrared absorbing RuIIIRuII intermediate

“…In conclusion, we identify the [(μ-adc-CF 3 ){Ru (bpy) 2 } 2 ] 3+ intermediate as a Ru III Ru II mixed-valent species involving hydrazido(2−) bridging ligand. This understanding implies a hole transfer mechanism [17] for the valence exchange in the excited state and an assignment of the strong near-infrared absorption as the result of a predominant intervalence charge transfer (IVCT) transition. With a bandwidth of about 1700 cm −1 at half height this absorption is much narrower than the 4800 cm −1 that is calculated from the Hush equation Δν(1 / 2) = (2310 × ε max ) 1/2 for localized mixedvalent systems [17], suggesting a valence-averaged situation in agreement with the high K c value.…”