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N-heterocyclic carbene complexes of Rh: reaction with dioxygen without oxidation.

TitleN-heterocyclic carbene complexes of Rh: reaction with dioxygen without oxidation.
Publication TypeJournal Article
Year of Publication2008
AuthorsPraetorius, JM, Allen, DP, Wang, R, Webb, JD, Grein, F, Kennepohl, P, Crudden, CM
JournalJ. Am. Chem. Soc.
Date Publishedmar
Keywordschemical, DFT, dioxygen complexes, Heterocyclic Compounds, Heterocyclic Compounds: chemistry, METHANE, Methane: analogs & derivatives, Methane: chemistry, models, MOLECULAR, molecular structure, ORGANOMETALLIC COMPOUNDS, Organometallic Compounds: chemical synthesis, Organometallic Compounds: chemistry, OXYGEN, Oxygen: chemistry, rhodium, Rhodium: chemistry, SPECTROMETRY, X-Ray Emission, X-Ray Emission: methods, XAS

The reaction of oxygen with rhodium complexes containing N-heterocyclic carbenes was found to give dioxygen complexes with rare square planar geometries and unusually short O-O bond lengths. Analysis of the bonding in these complexes by Rh L-edge X-ray absorption spectroscopy (XAS), Raman spectroscopy, and DFT calculations provides evidence for a bonding model in which singlet oxygen is bound to a Rh(I) d8 metal complex, rather than the more common Rh(III) d6 peroxo species with octahedral geometry and O-O bond lengths in the 1.4-1.5 A range.