Source:http://linkedlifedata.com/resource/pubmed/id/19905019
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
46
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| pubmed:dateCreated |
2009-11-12
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| pubmed:abstractText |
Optimized structures of the isoelectronic cumulenes (CCCB)(-), CCCC, and (CCCN)(+) and of their isomers formed by rearrangement have been calculated at the B3LYP/6-311+ G(3df) level of theory with relative energies and electronic states determined at the CCSD(T)/aug-cc-pVTZ level of theory. The ground states of CCCC and (CCCN)(+) are triplets, whereas the ground state of (CCCB)(-) is a quasi-linear singlet structure that is only 0.6 kcal mol(-1) more negative in energy than the linear triplet. When energized, both triplet and singlet CCCC cyclize to planar rhomboids, of which the singlet is the lowest-energy configuration. Ring-opening of rhomboid C(4) reforms CCCC with the carbons partially randomized. Similar rearrangements occur for (CCCB)(-) and (CCCN)(+), but the reactions are different in the detail. In the case of (CCCN)(+), rearrangement of atoms is supported both experimentally and theoretically. Because (CCCB)(-) and (CCCN)(+) are not symmetrical, two fully cyclized forms are possible; the one more resembling a rhomboid structure is called a "kite" structure, and the other is called a "fan" structure. The rearrangement of (CCCB)(-) is more favored via the triplet with equilibrating kite and fan structures being formed, whereas the singlet (CCCN)(+) ring closes to give the singlet kite structure, which may ring open to give a mixture of (CCCN)(+) and (CCNC)(+). Intersystem crossing may occur for the triplet and singlet forms of CCCC and (CCCB)(-) but not for (CCCN)(+).
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Nov
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| pubmed:issn |
1520-5215
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| pubmed:author | |
| pubmed:issnType |
Electronic
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| pubmed:day |
19
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| pubmed:volume |
113
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
12952-60
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| pubmed:year |
2009
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| pubmed:articleTitle |
Study of the isomers of isoelectronic C(4), (C(3)B)(-), and (C(3)N)(+): rearrangements through cyclic isomers.
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| pubmed:affiliation |
Department of Chemistry, The University of Adelaide, South Australia.
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| pubmed:publicationType |
Journal Article
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