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

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:
Grant/Contract Number:
EE0005658; P30 ES00210; EP/M024210; EP/J02127X
Type:
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
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)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; amine-borane; catalysis; iridium; phosphine; rhodium
OSTI Identifier:
1343064