Assignment of pre-edge features in the Ru K-edge X-ray absorption spectra of organometallic ruthenium complexes

Abstract

The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d←1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.

X-ray Absorption Near Edge Structure Spectroscopy to Resolve the in Vivo Chemistry of the Redox-Active Indazolium trans-[Tetrachlorobis(1H-indazole)ruthenate(III)] (KP1019)

“…The absence of any distinct pre-edge feature implies a centrosymmetric coordination of the here investigated Ru compounds. 52 …”

“…For 1 it was found that the indazole ligands are weaker donors toward Ru than imidazole ones, which is congruent with the proposed activation by reduction mechanism stated for 1 and its easier reduction to Ru(II) compared to the imidazole analogue trans -[tetrachlorobis(1 H -imidazole)ruthenate(III)] (KP418). 30,51 Getty et al 52 assigned Ru K-edge pre-edge peaks to the centrosymmetric structure of Ru carbene complexes for olefin metathesis. With increasing symmetry of the complexes the pre-edge peaks got weakened, which was ascribed to a lowered Ru 4d–5p orbital mixing.…”

Characterization of Structural and Electronic Transitions During Reduction and Oxidation of Ru(acac)3 Flow Battery Electrolytes by using X‐ray Absorption Spectroscopy

“…octahedral) around the metal; this is a common method of quantifying transitions from octahedral (no pre‐edge) to tetrahedral (strong pre‐edge) environments in metals. In the case of Ru, a weak pre‐edge shoulder is expected at 22 118 eV for non‐inversion‐symmetric species . The lack of this feature in oxidized Ru(acac) 3 (Figure ) indicates octahedral symmetry is maintained.…”

“…In the case of Ru, aw eak pre-edges houlder is expected at 22 118eVf or non-inversion-symmetrics pecies. [42] The lack of this feature in oxidized Ru(acac) 3 (Figure 5) indicates octahedral symmetry is maintained. Insights derived from resultsp resented in this paper are being used to functionalize the acetylacetone to mitigate side reactions.…”

Combustion activities of the Ru catalysts supported on hexagonal YbFeO3

“…Moreover, Ru/h-YbFeO 3 (ST-250) and Ru/h-YbFeO 3 (ST-230) exhibited a pre-edge peak at around 22110 eV. The existence of the pre-edge peak implies that the Ru species is distorted from the octahedral symmetry, 15), 16) suggesting that the distorted Ru species were formed on h-YbFeO 3 (ST-250) and YbFeO 3 (ST-230).…”