Synthesis, characterization and catalytic activity of saturated and unsaturated N-heterocyclic carbene iridium(I) complexes
Journal
Dalton Transactions
Journal Issue
5
Pages
861-867
Date Issued
2009
Author(s)
Abstract
Both saturated and unsaturated N-benzyl substituted heterocyclic carbene (NHC) iridum(i) complexes were synthesized. The unsaturated carbene complex [(un-NHC-Bn)Ir(CO)2Cl] in the cis form was prepared via the carbene transfer from the corresponding silver complex to [Ir(COD)2Cl] 2 followed by ligand substitution with CO, whereas the saturated complex was obtained via the transfer from (sat-NHC-Bn)W(CO)5. The treatment of phosphines with (NHC)Ir(CO)2Cl complexes yielded the products with the phosphine ligand trans to the carbene moiety via substitution. X-Ray structural determination shows that distances of Ir-C(carbene) in both (un-NHC-Bn)Ir(CO)(PR3)Cl and (un-NHC-Bn)Ir(CO)(PR 3)Cl are essentially the same. Analyses of spectroscopic and crystal structural data of iridium complexes [(NHC)Ir(CO)(PR3)Cl] and Vaska's complex show similar corresponding data in both types of complexes, suggesting that the studied NHC ligands and phosphines have similar bonding with Ir(i) metal center. All iridium complexes studied in this work illustrated their catalytically activity on N-alkylation of amine with alcohol via hydrogen transfer reduction. It appears no dramatic difference on the catalytic activity among these iridium carbene complexes; but the saturated carbene complex (sat-NHC-Bn)Ir(CO)(PR3)Cl appears to be slightly more active. For example, the reaction of benzyl alcohol with aniline in the presence of catalyst (1 mol%) under basic conditions at 100 °C provided the secondary amine (N-benzylaniline) in 96% yield. © 2009 The Royal Society of Chemistry.
SDGs
Other Subjects
Amines; Carbon monoxide; Catalyst activity; Electrochemical sensors; Hydrocarbons; Hydrogen; Iridium; Iridium compounds; Ligands; Organic compounds; Organic polymers; Phosphorus compounds; Semiconducting indium gallium arsenide; Silver; Silver compounds; Synthesis (chemical); Tungsten compounds; Benzyl alcohol (BA); Carbene; Carbene complexes; Carbene transfer; Catalytic activities; Hydrogen-transfer reduction; Iridium (III) complexes; Ligand substitution; Metal centers; N-alkylation; N-heterocyclic carbene (NHC); NHC ligands; Phosphine ligands; Synthesis (of chiral ionic liquids); Vaska's complex; Chlorine compounds; aniline; aniline derivative; benzyl alcohol; benzylaniline; carbene; drug derivative; heterocyclic compound; iridium; methane; organometallic compound; article; catalysis; chemical structure; chemistry; stereoisomerism; synthesis; X ray crystallography; Aniline Compounds; Benzyl Alcohol; Catalysis; Crystallography, X-Ray; Heterocyclic Compounds; Iridium; Methane; Models, Molecular; Molecular Structure; Organometallic Compounds; Stereoisomerism
Type
journal article