Cyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditions

Handle URI:
http://hdl.handle.net/10754/561467
Title:
Cyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditions
Authors:
Li, Shenyu; Kee, Choonwee; Huang, Kuo-Wei ( 0000-0003-1900-2658 ) ; Hor, Andy Sum Andy; Zhao, Jin
Abstract:
A series of N-heterocyclic carbene (NHC) complexes CpMo(CO) 2(NHC)X (NHC = IMe = 1,3-dimethylimidazol-2-ylidene, X = Br, 1; NHC = 1,3-dipropylimidazol-2-ylidene, X = Br, 2; NHC = IMes = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene, X = Br, 3; NHC = IBz = 1,3-dibenzylimidazol- 2-ylidene, X = Br, 4a, and X = Cl, 4b; NHC = 1-methyl-3-propylimidazol-2- ylidene, X = Br, 5) and [CpMo(CO)2(IMes)(CH3CN)][BF 4] (6) have been synthesized and fully characterized. The stability of metal-NHC ligand bonds in these compounds under oxidative conditions has been investigated. The thermally stable Mo(VI) dioxo NHC complex [CpMoO 2(IMes)][BF4] (9) has been isolated by the oxidation of the ionic complex 6 by TBHP (tert-butyl hydrogen peroxide). Complex 6 can be applied as a very active (TOFs up to 3400 h-1) and selective olefin epoxidation catalyst. While under oxidative conditions (in the presence of TBHP), compounds 1-5 decompose into imidazolium bromide and imidazolium polyoxomolybdate. The formation of polyoxomolybdate as oxidation products had not been observed in a similar epoxidation catalyzed by Mo(II) and Mo(VI) complexes. DFT studies suggest that the presence of Br- destabilizes the CpMo(VI) oxo NHC carbene species, consistent with the experimental observations. © 2010 American Chemical Society.
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division; KAUST Catalysis Center (KCC); Chemical Science Program; Physical Sciences and Engineering (PSE) Division; HCL
Publisher:
American Chemical Society (ACS)
Journal:
Organometallics
Issue Date:
26-Apr-2010
DOI:
10.1021/om900980a
Type:
Article
ISSN:
02767333
Sponsors:
We are grateful to the Ministry of Education (MOE) of Singapore Academic Research Fund (AcRF) Tier 1 Grant (WBS No. R-143-000-373-112). S.Y. L. also thanks National University of Singapore for the scholarship. K.W.H. acknowledges the support from KAUST baseline funding. We thank Ms. Geok Kheng Tan and Dr. Lip Lin Koh for determining the X-ray crystal structures.
Is Supplemented By:
Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748781: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct457b; DOI:10.5517/cct457b; HANDLE:http://hdl.handle.net/10754/624609; Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748782: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct458c; DOI:10.5517/cct458c; HANDLE:http://hdl.handle.net/10754/624610; Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748783: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct459d; DOI:10.5517/cct459d; HANDLE:http://hdl.handle.net/10754/624611; Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748784: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct45bf; DOI:10.5517/cct45bf; HANDLE:http://hdl.handle.net/10754/624612; Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748785: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct45cg; DOI:10.5517/cct45cg; HANDLE:http://hdl.handle.net/10754/624613; Li, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 810641: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccw6jq9; DOI:10.5517/ccw6jq9; HANDLE:http://hdl.handle.net/10754/624632
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC); Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorLi, Shenyuen
dc.contributor.authorKee, Choonweeen
dc.contributor.authorHuang, Kuo-Weien
dc.contributor.authorHor, Andy Sum Andyen
dc.contributor.authorZhao, Jinen
dc.date.accessioned2015-08-02T09:12:06Zen
dc.date.available2015-08-02T09:12:06Zen
dc.date.issued2010-04-26en
dc.identifier.issn02767333en
dc.identifier.doi10.1021/om900980aen
dc.identifier.urihttp://hdl.handle.net/10754/561467en
dc.description.abstractA series of N-heterocyclic carbene (NHC) complexes CpMo(CO) 2(NHC)X (NHC = IMe = 1,3-dimethylimidazol-2-ylidene, X = Br, 1; NHC = 1,3-dipropylimidazol-2-ylidene, X = Br, 2; NHC = IMes = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene, X = Br, 3; NHC = IBz = 1,3-dibenzylimidazol- 2-ylidene, X = Br, 4a, and X = Cl, 4b; NHC = 1-methyl-3-propylimidazol-2- ylidene, X = Br, 5) and [CpMo(CO)2(IMes)(CH3CN)][BF 4] (6) have been synthesized and fully characterized. The stability of metal-NHC ligand bonds in these compounds under oxidative conditions has been investigated. The thermally stable Mo(VI) dioxo NHC complex [CpMoO 2(IMes)][BF4] (9) has been isolated by the oxidation of the ionic complex 6 by TBHP (tert-butyl hydrogen peroxide). Complex 6 can be applied as a very active (TOFs up to 3400 h-1) and selective olefin epoxidation catalyst. While under oxidative conditions (in the presence of TBHP), compounds 1-5 decompose into imidazolium bromide and imidazolium polyoxomolybdate. The formation of polyoxomolybdate as oxidation products had not been observed in a similar epoxidation catalyzed by Mo(II) and Mo(VI) complexes. DFT studies suggest that the presence of Br- destabilizes the CpMo(VI) oxo NHC carbene species, consistent with the experimental observations. © 2010 American Chemical Society.en
dc.description.sponsorshipWe are grateful to the Ministry of Education (MOE) of Singapore Academic Research Fund (AcRF) Tier 1 Grant (WBS No. R-143-000-373-112). S.Y. L. also thanks National University of Singapore for the scholarship. K.W.H. acknowledges the support from KAUST baseline funding. We thank Ms. Geok Kheng Tan and Dr. Lip Lin Koh for determining the X-ray crystal structures.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleCyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditionsen
dc.typeArticleen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentChemical Science Programen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentHCLen
dc.identifier.journalOrganometallicsen
dc.contributor.institutionDepartment of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singaporeen
dc.contributor.institutionGerman Institute of Science and Technology-TUM Asia Pte. Ltd., Pixel Building, 10 Central Exchange Green, #03-01, 138649, Singapore, Singaporeen
kaust.authorHuang, Kuo-Weien
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748781: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct457ben
dc.relation.isSupplementedByDOI:10.5517/cct457ben
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624609en
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748782: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct458cen
dc.relation.isSupplementedByDOI:10.5517/cct458cen
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624610en
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748783: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct459den
dc.relation.isSupplementedByDOI:10.5517/cct459den
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624611en
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748784: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct45bfen
dc.relation.isSupplementedByDOI:10.5517/cct45bfen
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624612en
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 748785: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cct45cgen
dc.relation.isSupplementedByDOI:10.5517/cct45cgen
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624613en
dc.relation.isSupplementedByLi, S., Kee, C. W., Huang, K.-W., Hor, T. S. A., & Zhao, J. (2011). CCDC 810641: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccw6jq9en
dc.relation.isSupplementedByDOI:10.5517/ccw6jq9en
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624632en
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