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Reversible, metal-free hydrogen activation by frustrated Lewis pairs


Jiang, C; Blacque, O; Fox, T; Berke, H (2011). Reversible, metal-free hydrogen activation by frustrated Lewis pairs. Dalton Transactions, 40(5):1091-1097.

Abstract

The Lewis acid cyclohexylbis(pentafluorophenyl) boron 1, which exhibits about 15% lower Lewis acidity in comparison with B(C(6)F(5))(3), activates H(2) in the presence of the bulky Lewis bases 2,2,6,6-tetramethylpiperidine (TMP), 1,2,2,6,6-pentamethylpiperidine (PMP), tri-tert-butylphosphine (t-Bu(3)P) leading in facile reactions at room temperature to heterolytic splitting of dihydrogen and formation of the salts TMPH]CyBH(C(6)F(5))(2)] 2, PMPH]CyBH(C(6)F(5))(2)] 3 and t-Bu(3)PH]CyBH(C(6)F(5))(2)] 4, which could be dehydrogenated at higher temperatures. The related Lewis acid 1-phenyl-2-bis-(pentafluorophenyl) boryl]ethane 5 exhibiting about 10% lower Lewis acidity than B(C(6)F(5)) 3 is also capable of splitting H(2) in a heterolytic fashion in the presence of TMP, PMP and t-Bu3P yielding TMPH]PhC(2)H(4)BH(C(6)F(5))(2)] 6, PMPH]PhC(2)H(4)BH(C(6)F(5))(2)] 7 and t-Bu(3)PH]PhC(2)H(4)BH(C(6)F(5))(2)] 8. Under comparable conditions as for 2-4, the dehydrogenations of 6-8 were much slower. 4b and 6 were characterized by single crystal X-ray diffraction studies.

The Lewis acid cyclohexylbis(pentafluorophenyl) boron 1, which exhibits about 15% lower Lewis acidity in comparison with B(C(6)F(5))(3), activates H(2) in the presence of the bulky Lewis bases 2,2,6,6-tetramethylpiperidine (TMP), 1,2,2,6,6-pentamethylpiperidine (PMP), tri-tert-butylphosphine (t-Bu(3)P) leading in facile reactions at room temperature to heterolytic splitting of dihydrogen and formation of the salts TMPH]CyBH(C(6)F(5))(2)] 2, PMPH]CyBH(C(6)F(5))(2)] 3 and t-Bu(3)PH]CyBH(C(6)F(5))(2)] 4, which could be dehydrogenated at higher temperatures. The related Lewis acid 1-phenyl-2-bis-(pentafluorophenyl) boryl]ethane 5 exhibiting about 10% lower Lewis acidity than B(C(6)F(5)) 3 is also capable of splitting H(2) in a heterolytic fashion in the presence of TMP, PMP and t-Bu3P yielding TMPH]PhC(2)H(4)BH(C(6)F(5))(2)] 6, PMPH]PhC(2)H(4)BH(C(6)F(5))(2)] 7 and t-Bu(3)PH]PhC(2)H(4)BH(C(6)F(5))(2)] 8. Under comparable conditions as for 2-4, the dehydrogenations of 6-8 were much slower. 4b and 6 were characterized by single crystal X-ray diffraction studies.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2011
Deposited On:14 Mar 2012 13:42
Last Modified:05 Apr 2016 15:42
Publisher:Royal Society of Chemistry
ISSN:1477-9226
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:10.1039/c0dt01255f
Other Identification Number:ISI:000286390300016
Permanent URL: http://doi.org/10.5167/uzh-60402

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