Journal article
Synthesis of chiral N-heterocyclic carbene (NHC) ligand precursors and formation of ruthenium(II) complexes for transfer hydrogenation catalysts
Polyhedron, v 58, pp 162-170
13 Jul 2013
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Abstract
The S enantiomers of ester functionalized NHC ligand precursors, 1-[(2S)-1-ethoxy-3-methyl-1-oxobutan-2-yl]-3-ethyl-1H-imidazol-3-ium bromide (3a) and the methyl ester analog 3b, were synthesized from L-valine and fully characterized. The absolute stereochemistry of the chiral center was confirmed by single crystal X-ray diffraction (for 3a) and enantiopurity (of 3a and 3b) was determined by micellar electrokinetic chromatography. Deprotonation of this NHC ligand precursor (3a or 3b) and coordination to [RuCl2(p-cymene)](2) resulted in the isolation of a monodentate complex (with only NHC coordination) (4a or 4b) and a bidentate complex (5). In the bidentate complex, in addition to NHC coordination, a carboxylate donor group (from in situ hydrolysis of the ester) coordinates to Ru. All ruthenium complexes have been characterized by spectroscopic and analytical methods, plus single crystal X-ray diffraction for 4a and 5. The evidence shows that both Ru complexes are racemic, but with alternate synthetic methods perhaps racemization during complexation of 3a or 3b to metals could be avoided. The ruthenium complexes described herein serve as catalysts for ketone transfer hydrogenation in basic isopropanol. (C) 2012 Elsevier Ltd. All rights reserved.
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Details
- Title
- Synthesis of chiral N-heterocyclic carbene (NHC) ligand precursors and formation of ruthenium(II) complexes for transfer hydrogenation catalysts
- Creators
- Joseph DePasquale - Drexel UniversityNicholas J. White - Drexel UniversityErin J. Ennis - Drexel UniversityMatthias Zeller - Youngstown State UniversityJoe P. Foley - Drexel UniversityElizabeth T. Papish - Drexel University
- Publication Details
- Polyhedron, v 58, pp 162-170
- Publisher
- Elsevier
- Number of pages
- 9
- Grant note
- 0087210 / NSF; National Science Foundation (NSF) 48295-AC3 / ACS-PRF; American Cancer Society; American Chemical Society CHE-0846383 / NSF CAREER; National Science Foundation (NSF); NSF - Office of the Director (OD) YSU CAP-491 / Ohio Board of Regents 0846383 / Division Of Chemistry; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) Drexel University
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000321724500026
- Scopus ID
- 2-s2.0-84880151186
- Other Identifier
- 991019168788904721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Inorganic & Nuclear
- Crystallography