New Ruthenium Nitrosyl Pincer Complexes Bearing an O2 Ligand. Mono-Oxygen Transfer

We report on Ru(II)(μ2-O2) nitrosyl pincer complexes that can return to their original Ru(0) state by reaction with mono-oxygen scavengers. Potential intermediates were calculated by density functional theory (DFT) and a mechanism is proposed, revealing a new type of metal–ligand cooperation consist...

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Veröffentlicht in:Inorganic chemistry 2015-03, Vol.54 (5), p.2253-2263
Hauptverfasser: Fogler, Eran, Efremenko, Irena, Gargir, Moti, Leitus, Gregory, Diskin-Posner, Yael, Ben-David, Yehoshoa, Martin, Jan M. L, Milstein, David
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Sprache:eng
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Zusammenfassung:We report on Ru(II)(μ2-O2) nitrosyl pincer complexes that can return to their original Ru(0) state by reaction with mono-oxygen scavengers. Potential intermediates were calculated by density functional theory (DFT) and a mechanism is proposed, revealing a new type of metal–ligand cooperation consisting of activation of the O2 moiety by both the metal center and the NO ligand. Reaction of the Ru(0) nitrosyl complex 1 with O2 quantitatively yielded the crystallographically characterized Ru(II) (μ2-O2) nitrosyl complex 2. Reaction of 2 with the mono-oxygen scavengers phosphines or CO gave the Ru(0) complex 1 and phosphine oxides, or the carbonyl complex 3 (1 trapped by CO) and CO2, respectively. Reaction of 2 with 1 equiv of phosphine at room temperature or −40 °C resulted in immediate formation of half an equivalent of 1 and 1 equiv of phosphine oxide, while half an equivalent of 2 remained unchanged. Overnight reaction at room temperature of 2 with excess CO (≥3 equiv) resulted in 3 and CO2 gas as the only products. Reaction of 1 with 1 equiv of mono-oxygen source (dioxirane) at −78 °C yielded the Ru(II)(μ2-O2) complex 2. Similarly, reaction of the Ru(0) dearomatized complex 4 with O2 led to the crystallographicaly characterized Ru(II)(μ2-O2) complex 5. Further reaction of 5 with mono-oxygen scavengers (phosphines or CO) led to the Ru(0) complex 4 and phosphine oxides or complex 6 (4 trapped by CO) and CO2. When instead only 1 equiv of 5 was reacted with 1 equiv of phosphine at room temperature, immediate formation of half an equivalent of 4 and 1 equiv of phosphine oxide took place, while half an equivalent of 5 remained unchanged. When 5 reacted with an excess of CO (≥3 equiv), complex 6 and CO2 gas were the only products obtained. DFT studies indicate a new mode of metal–ligand cooperation involving the nitrosyl ligand in the oxygen transfer process.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic502832j