TY - JOUR
T1 - NiI/RuII model for the Ni-L state of the [NiFe]hydrogenases
T2 - Synthesis, spectroscopy, and reactivity
AU - Chambers, Geoffrey M.
AU - Mitra, Joyee
AU - Rauchfuss, Thomas B.
AU - Stein, Matthias
PY - 2014/4/21
Y1 - 2014/4/21
N2 - This study describes the characterization of a mixed-valence Ru II/NiI complex, a structural model for the Ni-L state of the [NiFe]hydrogenases. One-electron oxidation of (cymene)Ru(μ-pdt)Ni(diphos) ([1]0, diphos = dppe, C2H4(PPh 2)2; [2]0, diphos = dcpe, C2H 4(P(C6H11)2)2] affords the mixed-valence cations [(cymene)Ru(pdt)Ni(diphos)]+ ([1] + and [2]+). Crystallographic and spectroscopic measurements indicate that these cations are described as RuII/ NiI. Although [1]0 and [1]+ are very similar structurally, the following changes are notable: the Ni-P distances elongate upon oxidation, and the Ru-Ni distance changes insignificantly. The molecular and electronic structures of the Ni center in [1]+ approaches that observed in the [NiFe]hydrogenases. Density functional theory calculations indicate that [1]0 is best described as RuII/Ni 0, consistent with its oxidation to RuII/NiI in [1]+. The fast electron self-exchange rate of 107 M -1 s-1 between [1]0 and [1]+ suggests minor reorganization, more consistent with a Ni0/Ni I oxidation state change than a NiI/NiII couple. In solution, [1]+ slowly converts to [H1]+ and [1-H]+, with the latter being a complex of the thioaldehyde SCHCH2CH2S arising from C-H activation of the pdt backbone. Treatment of [1]+ with the H-atom abstracting reagent 2,2,6,6-tetramethylpiperidine-1-oxy also gives [1-H]+.
AB - This study describes the characterization of a mixed-valence Ru II/NiI complex, a structural model for the Ni-L state of the [NiFe]hydrogenases. One-electron oxidation of (cymene)Ru(μ-pdt)Ni(diphos) ([1]0, diphos = dppe, C2H4(PPh 2)2; [2]0, diphos = dcpe, C2H 4(P(C6H11)2)2] affords the mixed-valence cations [(cymene)Ru(pdt)Ni(diphos)]+ ([1] + and [2]+). Crystallographic and spectroscopic measurements indicate that these cations are described as RuII/ NiI. Although [1]0 and [1]+ are very similar structurally, the following changes are notable: the Ni-P distances elongate upon oxidation, and the Ru-Ni distance changes insignificantly. The molecular and electronic structures of the Ni center in [1]+ approaches that observed in the [NiFe]hydrogenases. Density functional theory calculations indicate that [1]0 is best described as RuII/Ni 0, consistent with its oxidation to RuII/NiI in [1]+. The fast electron self-exchange rate of 107 M -1 s-1 between [1]0 and [1]+ suggests minor reorganization, more consistent with a Ni0/Ni I oxidation state change than a NiI/NiII couple. In solution, [1]+ slowly converts to [H1]+ and [1-H]+, with the latter being a complex of the thioaldehyde SCHCH2CH2S arising from C-H activation of the pdt backbone. Treatment of [1]+ with the H-atom abstracting reagent 2,2,6,6-tetramethylpiperidine-1-oxy also gives [1-H]+.
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U2 - 10.1021/ic500389p
DO - 10.1021/ic500389p
M3 - Article
AN - SCOPUS:84899443649
SN - 0020-1669
VL - 53
SP - 4243
EP - 4249
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 8
ER -