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Title: The Synthesis, Characterization and Dehydrogenation of Sigma-Complexes of BN-Cyclohexanes

Abstract

The coordination chemistry of the 1,2-BN-cyclohexanes 2,2-R 2-1,2-B,N-C 4H 10 (R 2=HH, MeH, Me 2) with Ir and Rh metal fragments has been studied. This led to the solution (NMR spectroscopy) and solid-state (X-ray diffraction) characterization of [Ir(PCy 3) 2(H) 22η 2-H 2BNR 2C 4H 8)][BAr F 4] (NR 2=NH 2, NMeH) and [Rh( iPr 2PCH 2CH 2CH 2P iPr 2)(η 2η 2-H 2BNR 2C 4H 8)][BAr F 4] (NR 2=NH 2, NMeH, NMe 2). For NR 2=NH 2 subsequent metal-promoted, dehydrocoupling shows the eventual formation of the cyclic tricyclic borazine [BNC 4H 8] 3, via amino-borane and, tentatively characterized using DFT/GIAO chemical shift calculations, cycloborazane intermediates. For NR 2=NMeH the final product is the cyclic amino-borane HBNMeC 4H 8. The mechanism of dehydrogenation of 2,2-H,Me-1,2-B,N-C 4H 10 using the {Rh( iPr 2PCH 2CH 2CH 2P iPr 2)} + catalyst has been probed. Catalytic experiments indicate the rapid formation of a dimeric species, [Rh 2( iPr 2PCH 2CH 2CH 2P iPr 2) 2H 5][BAr F 4]. Using the initial rate method starting from this dimer, a first-order relationship to [amine-borane], but half-order to [Rh] is established, which is suggested to be due to a rapid dimer–monomer equilibrium operating.

Authors:
 [1];  [2];  [1];  [3];  [3];  [2];  [1]
  1. Univ. of Oxford (United Kingdom). Dept. of Chemistry
  2. Boston College, Chestnut Hill, MA (United States). Dept. of Chemistry
  3. Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Chemistry
Publication Date:
Research Org.:
Boston College, Chestnut Hill, MA (United States); Univ. of Alabama, Tuscaloosa, AL (United States); Univ. of Oxford (United Kingdom)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); National Inst. of Environmental Health Sciences (NIEHS) (United States); Rhodes Trust (United Kingdom); Engineering and Physical Sciences Research Council (EPSRC)
OSTI Identifier:
1343064
Grant/Contract Number:  
EE0005658; P30 ES00210; EP/M024210; EP/J02127X
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry - A European Journal
Additional Journal Information:
Journal Volume: 22; Journal Issue: 1; Journal ID: ISSN 0947-6539
Publisher:
ChemPubSoc Europe
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; amine-borane; catalysis; iridium; phosphine; rhodium

Citation Formats

Kumar, Amit, Ishibashi, Jacob S. A., Hooper, Thomas N., Mikulas, Tanya C., Dixon, David A., Liu, Shih-Yuan, and Weller, Andrew S.. The Synthesis, Characterization and Dehydrogenation of Sigma-Complexes of BN-Cyclohexanes. United States: N. p., 2015. Web. doi:10.1002/chem.201502986.
Kumar, Amit, Ishibashi, Jacob S. A., Hooper, Thomas N., Mikulas, Tanya C., Dixon, David A., Liu, Shih-Yuan, & Weller, Andrew S.. The Synthesis, Characterization and Dehydrogenation of Sigma-Complexes of BN-Cyclohexanes. United States. doi:10.1002/chem.201502986.
Kumar, Amit, Ishibashi, Jacob S. A., Hooper, Thomas N., Mikulas, Tanya C., Dixon, David A., Liu, Shih-Yuan, and Weller, Andrew S.. Wed . "The Synthesis, Characterization and Dehydrogenation of Sigma-Complexes of BN-Cyclohexanes". United States. doi:10.1002/chem.201502986. https://www.osti.gov/servlets/purl/1343064.
@article{osti_1343064,
title = {The Synthesis, Characterization and Dehydrogenation of Sigma-Complexes of BN-Cyclohexanes},
author = {Kumar, Amit and Ishibashi, Jacob S. A. and Hooper, Thomas N. and Mikulas, Tanya C. and Dixon, David A. and Liu, Shih-Yuan and Weller, Andrew S.},
abstractNote = {The coordination chemistry of the 1,2-BN-cyclohexanes 2,2-R2-1,2-B,N-C4H10 (R2=HH, MeH, Me2) with Ir and Rh metal fragments has been studied. This led to the solution (NMR spectroscopy) and solid-state (X-ray diffraction) characterization of [Ir(PCy3)2(H)2(η2η2-H2BNR2C4H8)][BArF4] (NR2=NH2, NMeH) and [Rh(iPr2PCH2CH2CH2PiPr2)(η2η2-H2BNR2C4H8)][BArF4] (NR2=NH2, NMeH, NMe2). For NR2=NH2 subsequent metal-promoted, dehydrocoupling shows the eventual formation of the cyclic tricyclic borazine [BNC4H8]3, via amino-borane and, tentatively characterized using DFT/GIAO chemical shift calculations, cycloborazane intermediates. For NR2=NMeH the final product is the cyclic amino-borane HBNMeC4H8. The mechanism of dehydrogenation of 2,2-H,Me-1,2-B,N-C4H10 using the {Rh(iPr2PCH2CH2CH2PiPr2)}+ catalyst has been probed. Catalytic experiments indicate the rapid formation of a dimeric species, [Rh2(iPr2PCH2CH2CH2PiPr2)2H5][BArF4]. Using the initial rate method starting from this dimer, a first-order relationship to [amine-borane], but half-order to [Rh] is established, which is suggested to be due to a rapid dimer–monomer equilibrium operating.},
doi = {10.1002/chem.201502986},
journal = {Chemistry - A European Journal},
number = 1,
volume = 22,
place = {United States},
year = {Wed Nov 25 00:00:00 EST 2015},
month = {Wed Nov 25 00:00:00 EST 2015}
}

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