Source:http://linkedlifedata.com/resource/pubmed/id/11804490
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
4
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| pubmed:dateCreated |
2002-1-23
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| pubmed:abstractText |
This paper reports a pH-dependent H2-activation [H2 (pH 1-4) --> H+ + H- (pH -1) --> 2H+ + 2e-] promoted by CpIr complexes [Cp = eta5-C5(CH3)5]. In a pH range of about 1-4, an aqueous HNO3 solution of [CpIr(III)(H2O)3]2+ (1) reacts with 3 equiv of H2 to yield a solution of [(CpIr(III))2(mu-H)3]+ (2) as a result of heterolytic H2-activation [2[1] + 3H2 (pH 1-4) --> [2] + 3H+ + 6H2O]. The hydrido ligands of 2 display protonic behavior and undergo H/D exchange with D+: [M-(H)3-M]+ + 3D+ <==>[M-(D)3-M]+ + 3H+ (where M = CpIr). Complex 2 is insoluble in a pH range of about -0.2 (1.6 M HNO3/H2O) to -0.8 (6.3 M HNO3/H2O). At pH -1 (10 M HNO3/H2O), a powder of 2 drastically reacts with HNO3 to give a solution of [CpIr(III)(NO3)2] (3) with evolution of H2, NO, and NO2 gases. D-labeling experiments show that the evolved H2 is derived from the hydrido ligands of 2. These results suggest that oxidation of the hydrido ligands of 2 [[2] + 4NO3- (pH -1) --> 2[3] + H2 + H+ + 4e-] couples to reduction of NO3- (NO3- --> NO2- --> NO). To complete the reaction cycle, complex 3 is transformed into 1 by increasing the pH of the solution from -1 to 1. Therefore, we are able to repeat the reaction cycle using 1, H2, and a pH gradient between 1 and -1. A conceivable mechanism for the H2-activation cycle with reduction of NO3- is proposed.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Jan
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| pubmed:issn |
0002-7863
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
30
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| pubmed:volume |
124
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
597-601
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| pubmed:dateRevised |
2003-10-31
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| pubmed:year |
2002
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| pubmed:articleTitle |
pH-dependent H2-activation cycle coupled to reduction of nitrate ion by CpIr complexes.
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| pubmed:affiliation |
Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
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| pubmed:publicationType |
Journal Article
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