Source:http://linkedlifedata.com/resource/pubmed/id/18459723
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| Predicate | Object |
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| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
11
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| pubmed:dateCreated |
2008-5-28
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| pubmed:abstractText |
Reaction of trans-(dmpe) 2CrCl2 (dmpe=1,2-bis(dimethylphosphino)ethane) with one equivalent of LiCCSiMe3 and one equivalent of nBuLi in THF under a dinitrogen atmosphere affords dark orange trans,trans-[(Me 3SiCC)(dmpe)2Cr]2(micro-N2).hexane (1). Under similar conditions but in the absence of acteylide ligand, the reaction of trans-(dmpe)2CrCl2 with 2 equivalents of nBuLi yields the previously characterized complex trans-(dmpe)2Cr(N2)2 (2), while the reaction of trans-(dmpe)2CrCl2 with 2 equivalents of LiCCSiMe3 in THF yields trans-(dmpe)2Cr(CCSiMe3)2 (3). Compound 3 can also be synthesized by irradiating a mixture of trans-(dmpe)2CrMe2 and HCCSiMe3 or by reduction of HCCSiMe3 with compound 2. The magnetic properties, electrochemistry, and crystal structure of trans,trans-[(Me3SiCC)(dmpe)2Cr]2(micro-N2) are consistent with the complex containing two CrI ions bridged by a neutral N2 moiety, with a 1.178(10) A N[TRIPLE BOND]N bond distance. For complex 1 redox processes centered at E1/2=-1.69 V (DeltaEp=185 mV) and -1.43 V (DeltaEp=182 mV) versus Fe(Cp)2/Fe(Cp)2+ are assigned to the CrICrI/CrICrII and CrICrII/CrIICrII couples, respectively. For trans-(dmpe)2Cr(CCSiMe3)2 a reversible couple assigned as the CrII/III couple was observed at -1.59 V (DeltaEp=242 mV) versus Fe(Cp)2/Fe(Cp)2+. The dinuclear CrI-dinitrogen complex 1 has a room temperature magnetic moment of 2.77 microB while compound 3 displays a moment of 2.55 microB. Density-functional theory calculations performed on a model compound of 1, namely, trans,trans-[(HCC)(dpe)2Cr]2(micro-N2) (dpe=diphospinoethane), indicate that oxidation of the molecule should result in weakening of the dinitrogen triple bond.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Jun
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| pubmed:issn |
0020-1669
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
2
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| pubmed:volume |
47
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
4639-47
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| pubmed:year |
2008
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| pubmed:articleTitle |
Dinitrogen and acetylide complexes of low-valent chromium.
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| pubmed:affiliation |
Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA. lberben@mit.edu
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| pubmed:publicationType |
Journal Article
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