Source:http://linkedlifedata.com/resource/pubmed/id/18672873
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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
17
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pubmed:dateCreated |
2008-8-27
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pubmed:abstractText |
The Mn (IV)(salen)(N 3) 2 complex ( 3) from Jacobsen's catalyst is synthesized, and the X-ray crystal structures of 3 as well as the starting Mn (III)(salen)(N 3)(CH 3OH) complex ( 2) are determined in order to investigate the conformation of the high-valent Mn (IV)(salen) molecule in comparison with that of Mn (III)(salen). The asymmetric unit of the crystal of 3 contains four complexes, all of which adopt a nonplanar stepped conformation effectively distorted by the chirality of the diimine bridge. The asymmetric unit of 2 also contains four complexes. Two of them show a stepped conformation of a lesser degree, but the other two adopt a bowl-shaped conformation. Comparison of the structural parameters shows that the Mn center in 3 is coordinated from both sides by two external axial N 3 ligands with significantly shorter bond lengths, which could induce greater preference for the stepped conformation in 3. The CH 3CN solution of 3 shows circular dichroism with a significantly strong band at 275 nm as compared to 2, suggesting that 3 may adopt a more chirally distorted conformation also in solution. The circular dichroism spectrum of 3 is slightly altered with isodichroic points from 298 to 253 K and shows no further change at temperatures lower than 253 K, suggesting that the solution of 3 contains an equilibrium between two conformers, where a low-energy conformer with more chiral distortion is predominantly favored even at room temperature. Complexes 2 and 3 are thoroughly characterized using various techniques including cyclic voltammetry, magnetic susceptibility, UV-vis, electron paramagnetic resonance, (1)H NMR, infrared spectroscopy, and electrospray ionization mass spectrometry.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
1520-510X
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pubmed:author | |
pubmed:issnType |
Electronic
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pubmed:day |
1
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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 |
7556-67
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pubmed:meshHeading |
pubmed-meshheading:18672873-Catalysis,
pubmed-meshheading:18672873-Crystallography, X-Ray,
pubmed-meshheading:18672873-Electrochemistry,
pubmed-meshheading:18672873-Electron Spin Resonance Spectroscopy,
pubmed-meshheading:18672873-Magnetic Resonance Spectroscopy,
pubmed-meshheading:18672873-Magnetics,
pubmed-meshheading:18672873-Manganese,
pubmed-meshheading:18672873-Models, Molecular,
pubmed-meshheading:18672873-Molecular Conformation,
pubmed-meshheading:18672873-Organometallic Compounds,
pubmed-meshheading:18672873-Spectrometry, Mass, Electrospray Ionization,
pubmed-meshheading:18672873-Spectrophotometry, Infrared,
pubmed-meshheading:18672873-Spectrophotometry, Ultraviolet,
pubmed-meshheading:18672873-Stereoisomerism,
pubmed-meshheading:18672873-Substrate Specificity
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pubmed:year |
2008
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pubmed:articleTitle |
Chiral distortion in a Mn(IV)(salen)(N3)2 derived from Jacobsen's catalyst as a possible conformation model for its enantioselective reactions.
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pubmed:affiliation |
Institute for Molecular Science & Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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