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Canote CA, Kilyanek SM. Reactivity of metal dioxo complexes. Dalton Trans 2024; 53:4874-4889. [PMID: 38379444 DOI: 10.1039/d3dt04390h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Metal dioxo chemistry and its diverse reactivity are presented with an emphasis on the mechanisms of reactivity. Work from approximately the last decade is surveyed and organized by metal. In particular, the chemistry of cis-dioxo metal complexes is discussed at length. Reactions are grouped by generic type, including addition across a metal oxo bond, oxygen atom transfer, and radical atom transfer reactions. Attention is given to advances in deoxygenation chemistry, oxidation chemistry, and reductive transformations.
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Affiliation(s)
- Cody A Canote
- Department of Chemistry and Biochemistry, 1 University of Arkansas, Fayetteville, AR 72701, USA.
| | - Stefan M Kilyanek
- Department of Chemistry and Biochemistry, 1 University of Arkansas, Fayetteville, AR 72701, USA.
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N-Donor Ligand Supported “ReO2+”: A Pre-Catalyst for the Deoxydehydration of Diols and Polyols. Catalysts 2020. [DOI: 10.3390/catal10070754] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A selected number of tetradentate N2Py2 ligand-supported ReO2+ complexes and a monodentate pyridine-supported ReO2+ complex have been investigated as catalysts for the deoxydehydration (DODH) of diols and polyols. In situ 1H NMR experiments showed that these N-donor ligand-supported ReO2+ complexes are only the pre-catalyst of the DODH reaction. Treatment of (N2Py2) ReO2+ with an excess amount of water generates an active species for DODH catalysis; use of the Re-product of this reaction shows a much shorter induction period compared to the pristine complex. No ligand is coordinated to the “water-treated” complex indicating that the real catalyst is formed after ligand dissociation. IR analysis suggested this catalyst to be a rhenium-oxide/hydroxide oligomer. The monodentate pyridine ligand is much easier to dissociate from the metal center than a tetradentate N2Py2 ligand, which makes the Py4ReO2+-initiated DODH reaction more efficient. For the Py4ReO2+-initiated DODH of diols and biomass-based polyols, both PPh3 and 3-pentanol could be used as a reductant. Excellent olefin yields are achieved.
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Tse CW, Liu Y, Wai-Shan Chow T, Ma C, Yip WP, Chang XY, Low KH, Huang JS, Che CM. cis-Oxoruthenium complexes supported by chiral tetradentate amine (N 4) ligands for hydrocarbon oxidations. Chem Sci 2018; 9:2803-2816. [PMID: 29780453 PMCID: PMC5943683 DOI: 10.1039/c7sc05224c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 02/01/2018] [Indexed: 12/31/2022] Open
Abstract
We report the first examples of ruthenium complexes cis-[(N4)RuIIICl2]+ and cis-[(N4)RuII(OH2)2]2+ supported by chiral tetradentate amine ligands (N4), together with a high-valent cis-dioxo complex cis-[(N4)RuVI(O)2]2+ supported by the chiral N4 ligand mcp (mcp = N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)cyclohexane-1,2-diamine). The X-ray crystal structures of cis-[(mcp)RuIIICl2](ClO4) (1a), cis-[(Me2mcp)RuIIICl2]ClO4 (2a) and cis-[(pdp)RuIIICl2](ClO4) (3a) (Me2mcp = N,N'-dimethyl-N,N'-bis((6-methylpyridin-2-yl)methyl)cyclohexane-1,2-diamine, pdp = 1,1'-bis(pyridin-2-ylmethyl)-2,2'-bipyrrolidine)) show that the ligands coordinate to the ruthenium centre in a cis-α configuration. In aqueous solutions, proton-coupled electron-transfer redox couples were observed for cis-[(mcp)RuIII(O2CCF3)2]ClO4 (1b) and cis-[(pdp)RuIII(O3SCF3)2]CF3SO3 (3c'). Electrochemical analyses showed that the chemically/electrochemically generated cis-[(mcp)RuVI(O)2]2+ and cis-[(pdp)RuVI(O)2]2+ complexes are strong oxidants with E° = 1.11-1.13 V vs. SCE (at pH 1) and strong H-atom abstractors with DO-H = 90.1-90.8 kcal mol-1. The reaction of 1b or its (R,R)-mcp counterpart with excess (NH4)2[CeIV(NO3)6] (CAN) in aqueous medium afforded cis-[(mcp)RuVI(O)2](ClO4)2 (1e) or cis-[((R,R)-mcp)RuVI(O)2](ClO4)2 (1e*), respectively, a strong oxidant with E(RuVI/V) = 0.78 V (vs. Ag/AgNO3) in acetonitrile solution. Complex 1e oxidized various hydrocarbons, including cyclohexane, in acetonitrile at room temperature, affording alcohols and/or ketones in up to 66% yield. Stoichiometric oxidations of alkenes by 1e or 1e* in t BuOH/H2O (5 : 1 v/v) afforded diols and aldehydes in combined yields of up to 98%, with moderate enantioselectivity obtained for the reaction using 1e*. The cis-[(pdp)RuII(OH2)2]2+ (3c)-catalysed oxidation of saturated C-H bonds, including those of ethane and propane, with CAN as terminal oxidant was also demonstrated.
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Affiliation(s)
- Chun-Wai Tse
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China . .,HKU Shenzhen Institute of Research and Innovation , Shenzhen , Guangdong 518053 , China
| | - Yungen Liu
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China . .,Department of Chemistry , Southern University of Science of Technology , Shenzhen , Guangdong 518055 , China
| | - Toby Wai-Shan Chow
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China .
| | - Chaoqun Ma
- Department of Chemistry , Southern University of Science of Technology , Shenzhen , Guangdong 518055 , China
| | - Wing-Ping Yip
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China .
| | - Xiao-Yong Chang
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China .
| | - Kam-Hung Low
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China .
| | - Jie-Sheng Huang
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China .
| | - Chi-Ming Che
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , China . .,HKU Shenzhen Institute of Research and Innovation , Shenzhen , Guangdong 518053 , China.,Department of Chemistry , Southern University of Science of Technology , Shenzhen , Guangdong 518055 , China
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