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Title: Silica-Supported Organolanthanum Catalysts for C–O Bond Cleavage in Epoxides

Abstract

Single-site organolanthanum complexes supported on mesoporous silica nanoparticles, La{C(SiHMe2)3}n@MSNs, catalyze the ring-opening hydroboration reaction of aliphatic and styrenic epoxides with pinacolborane (HBpin). The surface-bound complexes, synthesized by reaction of the homoleptic tris(alkyl)lanthanum La{C(SiHMe2)3}3 and SBA-type MSN treated at 700 °C (MSN700), are mostly monopodal ≡SiO—La{C(SiHMe2)3}2 and contain an average of one bridging La$$\leftharpoonup$$H—Si per alkyl ligand. This structure was established through a combination of solid-state NMR (SSNMR) experiments, including J-resolved SiH coupling and quantitative 29Si measurements, diffuse reflectance IR, and elemental analysis. Furthermore, these rigorous analyses also established that grafting reactions in pentane provide a preponderance of ≡SiO—La{C(SiHMe2)3}2 sites and are superior to those in benzene and THF, and that grafting onto MSN treated at 550 °C (MSN550) results in a mixture of surface species. The single-site supported catalysts are more selective and in most cases more active than the homogeneous analogue, allow easy purification of products from the catalyst, are strongly resistant to leaching into solution phase, and may be recycled for reuse at least five times. After reaction of La{C(SiHMe2)3}n@MSN and HBpin, species including ≡SiO—La{C(SiHMe2)3}(H2Bpin) and ≡SiO—La{C(SiHMe2)3}{κ2–pinB–O(CMe2)2OBH3} are identified by detailed 1D and 2D 11B SSNMR experiments.

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1601279
Report Number(s):
IS-J-10158
Journal ID: ISSN 0002-7863
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 142; Journal Issue: 6; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ligands; Ethers; Chemical structure; Catalysts

Citation Formats

Wang, Zhuoran, Patnaik, Smita, Eedugurala, Naresh, Manzano, J. Sebastián, Slowing, Igor I., Kobayashi, Takeshi, Sadow, Aaron D., and Pruski, Marek. Silica-Supported Organolanthanum Catalysts for C–O Bond Cleavage in Epoxides. United States: N. p., 2020. Web. doi:10.1021/jacs.9b11606.
Wang, Zhuoran, Patnaik, Smita, Eedugurala, Naresh, Manzano, J. Sebastián, Slowing, Igor I., Kobayashi, Takeshi, Sadow, Aaron D., & Pruski, Marek. Silica-Supported Organolanthanum Catalysts for C–O Bond Cleavage in Epoxides. United States. doi:10.1021/jacs.9b11606.
Wang, Zhuoran, Patnaik, Smita, Eedugurala, Naresh, Manzano, J. Sebastián, Slowing, Igor I., Kobayashi, Takeshi, Sadow, Aaron D., and Pruski, Marek. Sun . "Silica-Supported Organolanthanum Catalysts for C–O Bond Cleavage in Epoxides". United States. doi:10.1021/jacs.9b11606.
@article{osti_1601279,
title = {Silica-Supported Organolanthanum Catalysts for C–O Bond Cleavage in Epoxides},
author = {Wang, Zhuoran and Patnaik, Smita and Eedugurala, Naresh and Manzano, J. Sebastián and Slowing, Igor I. and Kobayashi, Takeshi and Sadow, Aaron D. and Pruski, Marek},
abstractNote = {Single-site organolanthanum complexes supported on mesoporous silica nanoparticles, La{C(SiHMe2)3}n@MSNs, catalyze the ring-opening hydroboration reaction of aliphatic and styrenic epoxides with pinacolborane (HBpin). The surface-bound complexes, synthesized by reaction of the homoleptic tris(alkyl)lanthanum La{C(SiHMe2)3}3 and SBA-type MSN treated at 700 °C (MSN700), are mostly monopodal ≡SiO—La{C(SiHMe2)3}2 and contain an average of one bridging La$\leftharpoonup$H—Si per alkyl ligand. This structure was established through a combination of solid-state NMR (SSNMR) experiments, including J-resolved SiH coupling and quantitative 29Si measurements, diffuse reflectance IR, and elemental analysis. Furthermore, these rigorous analyses also established that grafting reactions in pentane provide a preponderance of ≡SiO—La{C(SiHMe2)3}2 sites and are superior to those in benzene and THF, and that grafting onto MSN treated at 550 °C (MSN550) results in a mixture of surface species. The single-site supported catalysts are more selective and in most cases more active than the homogeneous analogue, allow easy purification of products from the catalyst, are strongly resistant to leaching into solution phase, and may be recycled for reuse at least five times. After reaction of La{C(SiHMe2)3}n@MSN and HBpin, species including ≡SiO—La{C(SiHMe2)3}(H2Bpin) and ≡SiO—La{C(SiHMe2)3}{κ2–pinB–O(CMe2)2OBH3} are identified by detailed 1D and 2D 11B SSNMR experiments.},
doi = {10.1021/jacs.9b11606},
journal = {Journal of the American Chemical Society},
number = 6,
volume = 142,
place = {United States},
year = {2020},
month = {1}
}

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This content will become publicly available on January 12, 2021
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