Source:http://linkedlifedata.com/resource/pubmed/id/17236226
Switch to
Predicate | Object |
---|---|
rdf:type | |
lifeskim:mentions | |
pubmed:issue |
10
|
pubmed:dateCreated |
2007-4-30
|
pubmed:abstractText |
Both experimental and theoretical evidence suggest that the proton exchange between water and the methyl group in [TpPt(CO)CH(3)] (1, Tp=hydridotripyrazolylborate) involves the formation and deprotonation of a "sticky" sigma-methane ligand. The efficiency of this nontrivial process has been attributed to the spatial orientation of functional groups that operate in concert to activate a water molecule and then achieve a multistep proton walk from water to an uncoordinated pyrazolyl nitrogen atom, to the methyl ligand, and then back to the nitrogen atom and water. The overall proton-exchange process has been proposed to involve an initial attack of water at the CO ligand in 1 with concerted deprotonation by the uncoordinated pyrazolyl nitrogen atom. The pyrazolium proton is then transferred to the Pt--CH(3) bond, leading to a sigma-methane intermediate. Subsequent rotation and deprotonation of the sigma-methane ligand, followed by reformation of 1 and water, result in scrambling of the methyl protons with the hydrogen atoms of water. An alternative two-step process that involves oxidative addition and reductive elimination has also been considered. The two competing mechanistic routes from 1 into [D(3)]-1, as well as the conversion of 1 into [TpPt(CH(3))H(2)] (2), have been examined by density functional theory (DFT) using a variety of exchange-correlation methods, primarily PW6B95, which was recently shown to be highly accurate for evaluating reactions of late-transition-metal complexes. The key role played by the free pyrazolyl nitrogen atom, acting as a proton carrier that abstracts a proton from water and transfers the proton to the Pt--CH(3) bond, is reminiscent of the dual functionality of histidine in the catalytic triad of natural serine proteases.
|
pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
|
pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Borates,
http://linkedlifedata.com/resource/pubmed/chemical/Ligands,
http://linkedlifedata.com/resource/pubmed/chemical/Methane,
http://linkedlifedata.com/resource/pubmed/chemical/Nitrogen,
http://linkedlifedata.com/resource/pubmed/chemical/Organometallic Compounds,
http://linkedlifedata.com/resource/pubmed/chemical/Platinum,
http://linkedlifedata.com/resource/pubmed/chemical/Protons,
http://linkedlifedata.com/resource/pubmed/chemical/Pyrroles,
http://linkedlifedata.com/resource/pubmed/chemical/Water,
http://linkedlifedata.com/resource/pubmed/chemical/hydridotrispyrazolylborate-(CO)2Mo(p...
|
pubmed:status |
MEDLINE
|
pubmed:issn |
0947-6539
|
pubmed:author | |
pubmed:issnType |
Print
|
pubmed:volume |
13
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
2812-23
|
pubmed:dateRevised |
2009-8-4
|
pubmed:meshHeading |
pubmed-meshheading:17236226-Borates,
pubmed-meshheading:17236226-Ligands,
pubmed-meshheading:17236226-Magnetic Resonance Spectroscopy,
pubmed-meshheading:17236226-Methane,
pubmed-meshheading:17236226-Models, Chemical,
pubmed-meshheading:17236226-Nitrogen,
pubmed-meshheading:17236226-Organometallic Compounds,
pubmed-meshheading:17236226-Platinum,
pubmed-meshheading:17236226-Protons,
pubmed-meshheading:17236226-Pyrroles,
pubmed-meshheading:17236226-Spectrometry, Mass, Electrospray Ionization,
pubmed-meshheading:17236226-Thermodynamics,
pubmed-meshheading:17236226-Water
|
pubmed:year |
2007
|
pubmed:articleTitle |
Proton walk in the aqueous platinum complex [TpPtMeCO] via a sticky sigma-methane ligand.
|
pubmed:affiliation |
Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
|
pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
|