Eser S. Akturk, Glenn P. A. Yap, and Klaus H. Theopold*
E. S. Akturk, Dr. G. P. A. Yap, Prof. Dr. K. H. Theopold
Department of Chemistry and Biochemistry
University of Delaware
Newark, DE 19716 (USA)
International Edition: DOI: 10.1002/anie.201508777
Angew. Chem. Int. Ed. 2015, 54, 14974 –14977
http://onlinelibrary.wiley.com/doi/10.1002/anie.201508777/epdf
Abstract: A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [TptBu,MeCrV- (O)2] (TptBu,Me=hydrotris(3-tert-butyl-5-methylpyrazolyl)borate),whereas the analogous reaction with sulfur stops at the persulfido complex [TptBu,MeCrIII(S2)]. The transformation of the putative peroxo intermediate [TptBu,MeCrIII(O2)] (S=3/2) into [TptBu,MeCrV(O)2] (S=1/2) is spin-forbidden. The minimum- energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex
[(TptBu,MeCr)2(m-O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface.
Figure 2. Reaction coordinate diagram for the spin-forbidden transformation
of A into 3. The structures shown are those calculated by DFT, showing the evolution of the O···O distance.
E. S. Akturk, Dr. G. P. A. Yap, Prof. Dr. K. H. Theopold
Department of Chemistry and Biochemistry
University of Delaware
Newark, DE 19716 (USA)
International Edition: DOI: 10.1002/anie.201508777
Angew. Chem. Int. Ed. 2015, 54, 14974 –14977
http://onlinelibrary.wiley.com/doi/10.1002/anie.201508777/epdf
Abstract: A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [TptBu,MeCrV- (O)2] (TptBu,Me=hydrotris(3-tert-butyl-5-methylpyrazolyl)borate),whereas the analogous reaction with sulfur stops at the persulfido complex [TptBu,MeCrIII(S2)]. The transformation of the putative peroxo intermediate [TptBu,MeCrIII(O2)] (S=3/2) into [TptBu,MeCrV(O)2] (S=1/2) is spin-forbidden. The minimum- energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex
[(TptBu,MeCr)2(m-O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface.
Figure 2. Reaction coordinate diagram for the spin-forbidden transformation
of A into 3. The structures shown are those calculated by DFT, showing the evolution of the O···O distance.
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