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Title: Thermodynamic Studies and Hydride Transfer Reactions from a Rhodium Complex to BX 3 Compounds

Abstract

This study examines the use of transition-metal hydride complexes that can be generated by the heterolytic cleavage of H 2 gas to form B–H bonds. Specifically, these studies are focused on providing a reliable and quantitative method for determining when hydride transfer from transition-metal hydrides to three-coordinate BX 3 compounds will be favorable. This involves both experimental and theoretical determinations of hydride transfer abilities. Thermodynamic hydride donor abilities (ΔG° H-) were determined for HRh(dmpe) 2 and HRh(depe) 2, where dmpe = 1,2-bis(dimethylphosphinoethane) and depe = 1,2-bis(diethylphosphinoethane), on a previously established scale in acetonitrile. This hydride donor ability was used to determine the hydride donor ability of [HBEt 3]⁻ on this scale. Isodesmic reactions between [HBEt 3]⁻ and various BX 3 complexes to form BEt 3 and [HBX 3]⁻ were examined computationally to determine the relative hydride affinities of various BX 3 compounds. The use of these scales of hydride donor abilities and hydride affinities for transition-metal hydrides and BX 3 compounds is illustrated with a few selected reactions relevant to the regeneration of ammonia borane. Our findings indicate that it is possible to form B-H bonds from B-X bonds, and the extent to which BX 3 compounds are reduced bymore » transition-metal hydride complexes forming species containing multiple B-H bonds depends on the heterolytic B-X bond energy. An example is the reduction of B(SPh) 3 using HRh(dmpe) 2 in the presence of triethylamine to form Et 3N-BH 3 in high yields. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
973723
Report Number(s):
PNNL-SA-67143
Journal ID: ISSN 0002-7863; JACSAT; EB4202000; TRN: US1002011
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 131; Journal Issue: 40; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ACETONITRILE; AMMONIA; CLEAVAGE; HYDRIDES; REGENERATION; RHODIUM; THERMODYNAMICS; TRANSFER REACTIONS

Citation Formats

Mock, Michael T, Potter, Robert G, Camaioni, Donald M, Li, Jun, Dougherty, William G, Kassel, W S, Twamley, Brendan, and DuBois, Daniel L. Thermodynamic Studies and Hydride Transfer Reactions from a Rhodium Complex to BX3 Compounds. United States: N. p., 2009. Web. doi:10.1021/ja905287q.
Mock, Michael T, Potter, Robert G, Camaioni, Donald M, Li, Jun, Dougherty, William G, Kassel, W S, Twamley, Brendan, & DuBois, Daniel L. Thermodynamic Studies and Hydride Transfer Reactions from a Rhodium Complex to BX3 Compounds. United States. https://doi.org/10.1021/ja905287q
Mock, Michael T, Potter, Robert G, Camaioni, Donald M, Li, Jun, Dougherty, William G, Kassel, W S, Twamley, Brendan, and DuBois, Daniel L. Wed . "Thermodynamic Studies and Hydride Transfer Reactions from a Rhodium Complex to BX3 Compounds". United States. https://doi.org/10.1021/ja905287q.
@article{osti_973723,
title = {Thermodynamic Studies and Hydride Transfer Reactions from a Rhodium Complex to BX3 Compounds},
author = {Mock, Michael T and Potter, Robert G and Camaioni, Donald M and Li, Jun and Dougherty, William G and Kassel, W S and Twamley, Brendan and DuBois, Daniel L},
abstractNote = {This study examines the use of transition-metal hydride complexes that can be generated by the heterolytic cleavage of H2 gas to form B–H bonds. Specifically, these studies are focused on providing a reliable and quantitative method for determining when hydride transfer from transition-metal hydrides to three-coordinate BX3 compounds will be favorable. This involves both experimental and theoretical determinations of hydride transfer abilities. Thermodynamic hydride donor abilities (ΔG°H-) were determined for HRh(dmpe)2 and HRh(depe)2, where dmpe = 1,2-bis(dimethylphosphinoethane) and depe = 1,2-bis(diethylphosphinoethane), on a previously established scale in acetonitrile. This hydride donor ability was used to determine the hydride donor ability of [HBEt3]⁻ on this scale. Isodesmic reactions between [HBEt3]⁻ and various BX3 complexes to form BEt3 and [HBX3]⁻ were examined computationally to determine the relative hydride affinities of various BX3 compounds. The use of these scales of hydride donor abilities and hydride affinities for transition-metal hydrides and BX3 compounds is illustrated with a few selected reactions relevant to the regeneration of ammonia borane. Our findings indicate that it is possible to form B-H bonds from B-X bonds, and the extent to which BX3 compounds are reduced by transition-metal hydride complexes forming species containing multiple B-H bonds depends on the heterolytic B-X bond energy. An example is the reduction of B(SPh)3 using HRh(dmpe)2 in the presence of triethylamine to form Et3N-BH3 in high yields. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.},
doi = {10.1021/ja905287q},
url = {https://www.osti.gov/biblio/973723}, journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 40,
volume = 131,
place = {United States},
year = {2009},
month = {10}
}