Title: Catalyst screening by electrospray ionization tandem mass spectrometry : Hofmann carbenes for olefin metathesis
Authors : Volland, Martin A. O.
Adlhart, Christian
Kiener, Christoph A.
Hofmann, Peter
Published in : Chemistry - A European Journal
Volume(Issue) : 7
Issue : 21
Pages : 4621
Pages to: 4632
Publisher / Ed. Institution : Wiley
Publisher / Ed. Institution: Hoboken, New Jersey
Issue Date: 5-Nov-2001
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Publication)
Language : English
Subject (DDC) : 540: Chemistry
Abstract: A screening methodol. combines in situ synthesis of complexes with an assay by electrospray ionization tandem mass spectrometry (ESI-MS) for evaluation of highly active, cationic ruthenium-carbene catalysts in ring-opening metathesis polymn. (ROMP). The parameter space, which is defined by systematic variation of four structural features of the catalyst [{R2P(CH2)nPR2-κ2P}XRu=CHR']+ (the halogen ligand, the diphosphane bite-angle, the steric bulk of the phosphane, and the carbene ligand) and the variation of the metathesis substrate, is mapped out. The 180 reactions (repeated 10 times each) were carried out in two weeks to map out the parameter space. Chloride as the anionic ligand X, a small chelating angle (n = 1), and reduced steric demand of the substituents R (Cy vs. tBu) lead to the most reactive complex in acyclic olefin metathesis, whereas variation of the carbene moiety CHR' has only a modest influence. The overall reaction rate in the gas phase depends on the π-complex preequil. and metallacyclobutane formation, the rate-detg. step. In ROMP reactions backbiting has a profound influence on the overall rate. The reactivity trends detd. in the gas phase parallel soln.-phase reactivity. The overall rate in soln. was also detd. by a favorable dimer/monomer preequil. providing the active catalyst by facile dissocn. of dicationic, dinuclear catalyst precursors.
Departement: Life Sciences und Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Article in scientific Journal
DOI : 10.1002/1521-3765(20011105)7:21<4621::AID-CHEM4621>3.0.CO;2-C
ISSN: 0947-6539
URI: https://digitalcollection.zhaw.ch/handle/11475/2093
Appears in Collections:Publikationen Life Sciences und Facility Management

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