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Copper(II)‐Mediated Aromatic ortho ‐Hydroxylation: A Hybrid DFT and Ab Initio Exploration
Author(s) -
Comba Peter,
Knoppe Stefan,
Martin Bodo,
Rajaraman Gopalan,
Rolli Claudio,
Shapiro Brett,
Stork Timon
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700865
Subject(s) - chemistry , ab initio , homolysis , density functional theory , hydroxylation , computational chemistry , bond cleavage , catalysis , radical , organic chemistry , enzyme
Mechanistic pathways for the aromatic hydroxylation by [Cu II ( L 1 )(TMAO)(O)] − ( L 1 =hippuric acid, TMAO=trimethylamine N ‐oxide), derived from the ON bond homolysis of its [Cu II ( L 1 )(TMAO) 2 ] precursor, were explored by using hybrid density functional theory (B3LYP) and highly correlated ab initio methods (QCISD and CCSD). Published experimental studies suggest that the catalytic reaction is triggered by a terminal copper–oxo species, and a detailed study of electronic structures, bonding, and energetics of the corresponding electromers is presented. Two pathways, a stepwise and a concerted reaction, were considered for the hydroxylation process. The results reveal a clear preference for the concerted pathway, in which the terminal oxygen atom directly attacks the carbon atom of the benzene ring, leading to the ortho ‐selectively hydroxylated product. Solvent effects were probed by using the PCM and CPCM solvation models, and the PCM model was found to perform better in the present case. Excellent agreement between the experimental and computational results was found, in particular also for changes in reactivity with derivatives of L 1 .