1421176-93-3Relevant academic research and scientific papers
Experimental and DFT evidence for the fractional non-innocence of a β-diketonate ligand
Das, Amit,Scherer, Thomas Michael,Mondal, Prasenjit,Mobin, Shaikh M.,Kaim, Wolfgang,Lahiri, Goutam Kumar
, p. 14434 - 14443 (2012)
New compounds [Ru(pap)2(L)](ClO4), [Ru(pap)(L) 2], and [Ru(acac)2(L)] (pap=2-phenylazopyridine, L -=9-oxidophenalenone, acac-=2,4-pentanedionate) have been prepared and studied regarding their electron-transfer behavior, both experimentally and by using DFT calculations. [Ru(pap)2(L)](ClO 4) and [Ru(acac)2(L)] were characterized by crystal-structure analysis. Spectroelectrochemistry (EPR, UV/Vis/NIR), in conjunction with cyclic voltammetry, showed a wide range of about 2 V for the potential of the RuIII/II couple, which was in agreement with the very different characteristics of the strongly π-accepting pap ligand and the σ-donating acac- ligand. At the rather high potential of +1.35 V versus SCE, the oxidation of L- into L. could be deduced from the near-IR absorption of [RuIII(pap)(L .)(L-)]2+. Other intense long-wavelength transitions, including LMCT (L-→RuIII) and LL/CT (pap.-→L-) processes, were confirmed by TD-DFT results. DFT calculations and EPR data for the paramagnetic intermediates allowed us to assess the spin densities, which revealed two cases with considerable contributions from L-radical-involving forms, that is, [Ru III(pap0)2(L-)]2+→ [RuII(pap0)2(L.)]2+ and [RuIII(pap0)(L-)2] +→[RuII(pap0)(L·)(L -)]+. Calculations of electrogenerated complex [Ru II(pap.-)(pap0)(L-)] displayed considerable negative spin density (-0.188) at the bridging metal. Copyright
