Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center
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1998
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Recent experimental work shows that alkanes can be activated by Cp*Ir(PMe3)(CH3)(+) at room temperature to generate olefin complexes. The reaction begins with alkane activation by oxidative addition (OA) followed by reductive elimination (RE) of methane and then olefin formation by the beta-H transfer from the bound alkyl. Ab initio calculations and density functional theory (DFT) studies of ethane activation by CpIr(PH3)(CH3)(+) (1) to generate CpIr(PH3)(eta(2)-C2H4)(H)(+) (7) show that the beta-H transfer from CpIr(PH3)(C2H5)(+) (5) to 7 is exothermic by 12 and 16 kcal/mol with a very low barrier of 0.7 and 0.4 kcal/mol at the DFT and CCSD levels, respectively. Thus, the rate-determining step in alkane dehydrogenation to olefin complexes by Cp*Ir(PMe3)(CH3)(+) is the alkane OA step. These results are in very good agreement with the experimental work of Bergman and co-workers. A strong stabilizing interaction between either ethylene or acetylene and CpIr(PH3)(CH3)(+) leads to high act...ivation barriers (25-36 kcal/mol) for the insertion processes of ethylene or acetylene. In comparison to ethylene, the insertion reaction of acetylene with the CpIr(PH3)(CH3)(+) complex is more favorable. Thus, the dimerization of terminal alkynes catalyzed by cationic iridium complexes is plausible.
Извор:
Organometallics, 1998, 17, 23, 5139-5147Издавач:
- Amer Chemical Soc, Washington
DOI: 10.1021/om980429n
ISSN: 0276-7333
WoS: 000077119200030
Scopus: 2-s2.0-0001393768
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Институција/група
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Niu, SQ AU - Zarić, Snežana D. AU - Bayse, CA AU - Strout, DL AU - Hall, Michael B. PY - 1998 UR - https://cherry.chem.bg.ac.rs/handle/123456789/399 AB - Recent experimental work shows that alkanes can be activated by Cp*Ir(PMe3)(CH3)(+) at room temperature to generate olefin complexes. The reaction begins with alkane activation by oxidative addition (OA) followed by reductive elimination (RE) of methane and then olefin formation by the beta-H transfer from the bound alkyl. Ab initio calculations and density functional theory (DFT) studies of ethane activation by CpIr(PH3)(CH3)(+) (1) to generate CpIr(PH3)(eta(2)-C2H4)(H)(+) (7) show that the beta-H transfer from CpIr(PH3)(C2H5)(+) (5) to 7 is exothermic by 12 and 16 kcal/mol with a very low barrier of 0.7 and 0.4 kcal/mol at the DFT and CCSD levels, respectively. Thus, the rate-determining step in alkane dehydrogenation to olefin complexes by Cp*Ir(PMe3)(CH3)(+) is the alkane OA step. These results are in very good agreement with the experimental work of Bergman and co-workers. A strong stabilizing interaction between either ethylene or acetylene and CpIr(PH3)(CH3)(+) leads to high activation barriers (25-36 kcal/mol) for the insertion processes of ethylene or acetylene. In comparison to ethylene, the insertion reaction of acetylene with the CpIr(PH3)(CH3)(+) complex is more favorable. Thus, the dimerization of terminal alkynes catalyzed by cationic iridium complexes is plausible. PB - Amer Chemical Soc, Washington T2 - Organometallics T1 - Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center VL - 17 IS - 23 SP - 5139 EP - 5147 DO - 10.1021/om980429n ER -
@article{ author = "Niu, SQ and Zarić, Snežana D. and Bayse, CA and Strout, DL and Hall, Michael B.", year = "1998", abstract = "Recent experimental work shows that alkanes can be activated by Cp*Ir(PMe3)(CH3)(+) at room temperature to generate olefin complexes. The reaction begins with alkane activation by oxidative addition (OA) followed by reductive elimination (RE) of methane and then olefin formation by the beta-H transfer from the bound alkyl. Ab initio calculations and density functional theory (DFT) studies of ethane activation by CpIr(PH3)(CH3)(+) (1) to generate CpIr(PH3)(eta(2)-C2H4)(H)(+) (7) show that the beta-H transfer from CpIr(PH3)(C2H5)(+) (5) to 7 is exothermic by 12 and 16 kcal/mol with a very low barrier of 0.7 and 0.4 kcal/mol at the DFT and CCSD levels, respectively. Thus, the rate-determining step in alkane dehydrogenation to olefin complexes by Cp*Ir(PMe3)(CH3)(+) is the alkane OA step. These results are in very good agreement with the experimental work of Bergman and co-workers. A strong stabilizing interaction between either ethylene or acetylene and CpIr(PH3)(CH3)(+) leads to high activation barriers (25-36 kcal/mol) for the insertion processes of ethylene or acetylene. In comparison to ethylene, the insertion reaction of acetylene with the CpIr(PH3)(CH3)(+) complex is more favorable. Thus, the dimerization of terminal alkynes catalyzed by cationic iridium complexes is plausible.", publisher = "Amer Chemical Soc, Washington", journal = "Organometallics", title = "Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center", volume = "17", number = "23", pages = "5139-5147", doi = "10.1021/om980429n" }
Niu, S., Zarić, S. D., Bayse, C., Strout, D.,& Hall, M. B.. (1998). Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center. in Organometallics Amer Chemical Soc, Washington., 17(23), 5139-5147. https://doi.org/10.1021/om980429n
Niu S, Zarić SD, Bayse C, Strout D, Hall MB. Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center. in Organometallics. 1998;17(23):5139-5147. doi:10.1021/om980429n .
Niu, SQ, Zarić, Snežana D., Bayse, CA, Strout, DL, Hall, Michael B., "Theoretical studies of inorganic and organometallic reaction mechanisms. 14. beta-hydrogen transfer and alkene/alkyne insertion at a cationic iridium center" in Organometallics, 17, no. 23 (1998):5139-5147, https://doi.org/10.1021/om980429n . .