Center for Catalysis, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, USA.
Published: April 2009
AI Article Synopsis
Article Abstract
New iridium and rhodium complexes prepared from C2-symmetric trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(1-R)-benzimidazolidine-2-ylidene ligands (R=Me, iPr, and diPh) have been synthesized and characterized. Their catalytic activities have been tested in enantioselective hydrogenation and hydroformylation reactions. The ee's for the reactions are low. Evidence indicates that even chelating di-N-heterocyclic carbene ligands are susceptible to reductive elimination.
Key Laboratory of Life-Organic Analysis of Shandong Province, Key Laboratory of Green Natural Products and Pharmaceutical Intermediates in Colleges and Universities of Shandong Province, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China.
The incorporation of an organelle-targeting moiety into compounds has proven to be an effective strategy in the development of targeted anticancer drugs. We herein report the synthesis, characterization, and biological evaluation of novel triphenylphosphine-modified half-sandwich iridium, rhodium, and ruthenium complexes. The primary goal was to enhance anticancer selectivity through mitochondrial targeting.
In this study, comprehensive density functional theory calculations were conducted to investigate the molecular mechanism of electrocatalytic proton reduction using group 9 transition metal bpaqH (2-(bis(pyridin-2-ylmethyl)amino)--(quinolin-8-yl)acetamide) complexes. The goal was to explore how variations in the structural and electronic properties among the three metal centers might impact the catalytic activity. All three metal complexes were observed to share a similar mechanism, primarily characterized by three key steps: heterolytic cleavage of H (HEP), reduction protonation (RPP), and ligand-centered protonation (LCP).
Stable neutral metal radicaloid complexes have been synthesized from a modified tetrapyrrolic pigment, bilatriene, with iridium(I) and rhodium(I) cyclooctadiene (COD) synthons. The bilatriene skeleton contains α-linked conjugated pyrrole units, whereas an N-confused analogue used in this work possesses β-linked pyrrole moieties at the terminal, demonstrating a unique metal binding capability. Unprecedentedly, the metal-COD cations are accommodated at the outer nitrogen sites, which induced the formation of open-shell metal-radicaloid species.
Chiral cyclopentadienyl (Cp) metal complexes are frequently used in asymmetric catalysis by virtue of their high reactivity and selectivity. Planar-chiral-only rhodium and iridium cyclopentadienyl complexes are particularly promising due to unrestricted chemical space for Cp ligand design while retaining structural simplicity. However, they are currently still niche because of a lack of efficient synthetic strategies that avoid lengthy chiral auxiliary routes or chiral preparatory HPLC resolution of the complexes.
This publication describes monodentate phosphine and oxazoline ligands attached to an amino acid ester and the application of their supramolecularly assembled rhodium(I) or iridium(I) complexes in asymmetric catalysis. The major feature of these complexes is the transmission of chirality from distant hydrogen bonded amino acids to the prochiral catalytic metal center ("backdoor induction"). The generated homoleptic and heteroleptic rhodium(I) or iridium(I) precatalysts were studied by NMR, UV-VIS and CD spectroscopy as well as X-ray single crystal diffraction.
